Frigid and Flourishing: Freeze-Proof

This post series opened with Part 1, an exploration of some snow-dwelling lifeforms.

The sun sets on the Yukon Territory’s Porcupine River, slowly melting into a far-off, lazy oxbow, pouring its tangerine light one last time over the endless, icy stillness. It’s just before four in the afternoon, the New Year is soon approaching, and it is cold. Very, very cold. As the blue above dims, and the blinding mango creamsicle spectacle comes to a rapid close in the west, you can almost hear the river ice creak and wince in anticipation for what’s coming. It only got up to 20 below today. The nights have grown large this time of year, and cruel. First light won’t come for what seems like eternity, and by then, the air will be a devastating -60 degrees Fahrenheit. Cold enough to kill exposed human skin in a handful of minutes. Cold enough to turn even antifreeze-laden gasoline into flammable slush. Cold enough for breath to stiffen in an instant, collecting as a growing layer of biting rime on every hair on one’s own face; eyelashes, eyebrows, the whole bit. In the growing dark, nothing moves. Chickadees settle into tree cavities, and rapidly begin burning through the fat reserves they gained during the day’s feeding, all just to keep warm. Caribou huddle and lay low. Ptarmigan wriggle into the snow (surprisingly, for insulation), stoking their metabolic fires with a crop pouch full of food. To survive the night, Life winds down everywhere, becoming motionless and dipping unnervingly near death in a desperate attempt to stay alive.

Well, everywhere except within the cramped, moist layers of bark of the naked balsam poplars lining the riverbank, stony and brittle with the cold. In there, somehow, life stirs, pushing and wriggling its way through its frozen, wooden den. It’s a tiny beetle grub, a larva of the northern red flat bark beetle (Cucujus clavipes puniceus), no longer than the graphite tip of a well-sharpened pencil. It has no blanket of thick fur or fluffy feathers, no fat-powered metabolic oven to keep it warm. It is a bare-assed worm, twenty feet up in a barren, ligneous spire, sandwiched between the unrelenting sadism of the Arctic atmosphere and a block of nearly lifeless wood….possibly the worst possible location for cold exposure. And yet, it is comfortable, its teeny body barely noticing the silent, breath-stealing chill invading from outside the bark.

Why? Because when the frosty grip of boreal death extends its hand, the larval red flat bark beetle tells it to fuck off.

Not bad for something that looks like a condom filled with urine-flavored Jello.

The red flat bark beetle ranges across a huge latitudinal swath of North America; from the Carolinas north and west into northern Canada and Alaska. As its name implies, this insect is the opposite of a claustrophobe, spending its entire life squeezed under the bark layer of trees, living or dead. They are particularly fond of deciduous trees like poplars, ashes, and oaks. In their mature state, red flat bark beetles are significantly more attractive creatures. The adult beetles are a bit smaller than their grub form, and have a clean, rectangular, distinctly compressed shape, all the while appearing to be made out of a rich, well-oiled mahogany.

Those wing cases double as a cellarette.
Photo: Mark Leppin

Of course, there are LOTS of bark beetles in the world. Split open any given piece of rotting lumber while out in the forest, and you’ll likely see at least several species of adult bark beetle scuttle out of the light. If you take a closer look, you might see larvae of additional species boring sinuous trails into wood itself. Dead wood and beetles go together like chicken and waffles. In that regard, the red flat bark beetle isn’t all that special. But not all bark beetles have mastered survival in otherworldly winter conditions like this species has.

Most insects tend to not want to tangle with the full brunt of subzero winter conditions. They’ll hibernate in warm, huddled piles until warm weather returns, or, as in the case of monarch butterflies or green darner dragonflies, they’ll simply migrate to more amiable southern climes for half the year. But the red flat bark beetle holds its ground, staying put in its insulation-deficient home, even in the face of insane temperature extremes. It doesn’t have a death wish, and it’s no haggard, masochistic badass. The larvae of these beetles overwinter through a harsh, Hothian hellscape….well…because they have a superpower up their sleeve.

They are really, really hard to freeze.

Red flat bark beetles act like miniature Wim Hofs because they have evolved a unique strategy for dealing with winter; that is, producing a number of chemicals in their bodies that make them exceptionally difficult to crystallize. They winterize themselves, like you would your home or car, and begin saturating their tissues with specific compounds that they make directly within their own bodies. As summer comes to a close, the beetles begin to create and store proteins that have potent antifreeze properties, thought to work by migrating and sticking to places in the body where ice crystals are likely to form. As fall drags on, the beetles start producing glycerol, which, like the ethylene glycol found in a jug of Prestone antifreeze, chemically interferes with the ability of water molecules to form a crystal lattice…making the freezing point of whatever it’s added to to drop like a rock. The western subspecies, Cucujus clavipes puniceus, which ranges much further north (into Alaska and the Yukon) than the eastern subspecies (which is more centered around the Eastern U.S. and Great Lakes region) produces a great deal more of these antifreeze compounds.

When the really cold temperatures hit, the beetles will dehydrate themselves, avoiding freezing by purging themselves of the thing most likely to freeze inside of them: water. These beetles use chemical aids to alter themselves in such a way that they can triumph over exceedingly difficult situations, which, in a way, is a method I recently employed to make it through watching Sarah Palin endorse Donald Trump for President.

*quietly in the background*
“…how ‘bout the rest of us? Right wingin’, bitter clingin’, proud clingers of our guns, our god, and our religions, and our Constitution…”

This jumping through stepwise biochemical hoops produces a kind of extreme “freeze-avoidance”, where the bark beetle doesn’t engage in behaviors that make it less freezable, but directly changes the composition of its body to provide freeze immunity. Without this suite of in-house developed potions and techniques, a brief brush with just a brisk, Arctic Circle autumn evening would leave these larvae stiffer than a Solo in carbonite.

So, how does the freeze-free solution of the Cucujus bark beetle hold up against the most intense possible side of the low Arctic winter months? How far can they stand the mercury to shrink? Well, there’s a good way to find an answer to that question, and it involves sticking thermocouples on some very unhappy beetles, throwing them in glass containers, and dipping those containers in an alcohol-water cooling bath….and then waiting for the cold to do its work.

It turns out that as the temperature drops, the red flat bark beetle larvae tend to do just fine staying still and enduring the chill without any major physiological changes until about -75 degrees Fahrenheit (-60 degrees Celsius). Right around there, at temperatures about as cold as it ever gets in this far northern habitat, something remarkable happens to many of the beetle larvae.

The bastards turn to glass.

Well, technically speaking, they “vitrify”, meaning that instead of allowing ice to form and crystallize all the fluids in their soft, water balloon bodies, they congeal into a stable, non-crystalline, solid state…or a “glass.” In the case of the beetle larvae, this is less like becoming an elegant, clear wine glass, and more like morphing into the world’s least appetizing flavor of Jolly Rancher. In this bizarre state, the larvae can avoid freezing outright down to an unreal -238 degrees Fahrenheit (-150 degrees Celsius) like a bunch of indestructible Werther’s Originals. That being said, just because these larvae manage to keep from turning to ice, it doesn’t mean they survive the ordeal. Only a tiny fraction of those subjected to temperatures below -94 degrees Fahrenheit (-70 degrees Celsius) continued to live after being rewarmed to room temperature and brought back out of their glass form. At this point, it appears as though the red flat bark beetle’s physiology is capable of amazing feats in extreme temperatures that it would likely never encounter in the wild, but in the end, it’s as if the beetle’s freeze-avoiding ego writes checks its body can’t cash.

A similar winter survival adaptation can be found in another species of beetle: the roughened darkling beetle (Upis ceramboides), which is also found in northern North America, as well as across the Eurasian subarctic. However, these insects technically become beetlesicles at around 20 degrees below Fahrenheit, but apparently produce a complex sugar-derived polymer called xylomannan that allows survival at much, much colder temperatures, possibly by keeping the ice crystals that form in the fluid between cells from actually piercing and rupturing the thin membranes enveloping these living cells. This full-frosty, “freeze-tolerant” method of survival evolved independently and in parallel with the “freeze-avoidant” measures taken by the red flat bark beetles.

A rare photo of Upis ceramboides heroically taking on the worst winter can throw its way.

All this side-stepping of a grim, glacial demise would surely be a welcome addition to the repertoire of skills held by many other bark beetle species, including some that are common prey to both the predaceous young and adult red flat bark beetles and their close relatives in the genus Cucujus. Among them are the mountain pine beetles (Dendroctonus ponderosae), a member of the weevil family (Curculionidae) found all over western North America, from British Columbia south into Mexico. Mountain pine beetles feed and reproduce under the bark of a number of species of pine tree found in the region. These beetles don’t have the extreme cold tolerance found in either the red flat bark beetles or the Upis beetles, and periodically succumb to periods of exceptionally cold weather. Traditionally, this has been a good thing for the ecosystems they inhabit, because mountain pine beetles have an impact on their host trees that is incredibly disproportional to their small size. The beetles lay their eggs inside the bark layer, and the young feed and bore into the sensitive, life-giving sap layers deeper into the tree. The beetles also introduce a variety of pathogenic fungus into the tree, and the combination of beetle infestation and fungal infection messes with the tree’s nutrient transport system so badly, that in a number of weeks, the tree will die. Under normal, moderate infestation conditions, this actually works out well for the forest. Unhealthy, vulnerable trees are put out of their misery before any others, and new, vibrant forest grows up in their place, and the beetles manage to contribute to the forest’s sensitive nutrient cycle. Occasional spikes of bitter cold in the winters would assist in keeping beetle numbers low. The forest gets spruced up (so to speak) every so often by beetle culling, the beetles never have a chance to get too numerous and overwhelming due to a cold snap here and there. Everything in perfect harmony, right?

Sure. But things go to shit pretty quickly when you throw in drought (which stresses out the trees and makes them acutely less likely to handle beetle infestation well) and incrementally rising temperatures, which make cold snaps occur less frequently…if at all. If this double-pronged scenario sounds familiar to you, then you’ve probably seen what’s been happening to the expansive evergreen forests that blanket the Mountain West over the past several decades. Climate change, through warmer, shorter winters and hotter, drier summers has allowed the beetles to run roughshod over North America’s pine forests. And the effects can be observed in all their depressing glory anywhere in the Rockies, as endless stands of what was healthy, verdant pine forest as little as five or ten years before, has been replaced by the rusty brush of thirsty, coniferous death similar to the remains of a discarded Christmas tree in a late-January dumpster.

These aren’t happy little trees from Bob Ross’s “Red Period.” These are standing corpses, victims of an insect unchained.

I’ve seen these forests riddled with “beetle kill” first hand, having spent seven years of my childhood living in remote central Idaho. I remember seeing the first notable brick-colored speckling in the high-elevation forests in the Sawtooth Range at the close of the 90s, and within a handful of years, green trees seemed to become a minority. The current outbreak of mountain pine beetles, no longer challenged by stiff winters, robust plant defenses, or any barriers to explosive reproduction, is of epic proportions, but more recently, there are signs in certain regions (like Colorado) that localized beetle numbers have fallen…but potentially only because so few suitable trees remain for exploitation.

Perhaps the mountain pine beetle would complain that it literally shivers in timbers, unlike the winter weather champion beetles to their north, but thanks to the consequences of human-driven climate fuckery, they might not have any use for potent freeze-mitigation adaptations for a long, long while.

Image credits: Intro composite of beetle in ice bath (from images here and here), larval red flat bark beetle, beetle kill forest vista

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Frigid and Flourishing: Life in the Snowscape


It’s now January, which means that up here in the Northern Hemisphere, it is, generally speaking, the coldest time of year. The days are still short, barely rounding the bend from their shortest point on the solstice, and the sun cuts a tentative, shallow angle across bleak, sleepy skies, darting back under the horizon almost as soon as it emerged, as if it was trying to escape the nippy atmosphere and curl up under the warm cover of night.

The arrival into this annual temperature trough is sitting prominently in my mind these days for a variety of reasons:

  1. My beloved Seattle Seahawks, just this weekend, made a miraculous win in Minnesota, despite enduring the full, sub-zero fury of the Gopher State, with windchill reaching a lung-punching 20-below, making it the third coldest NFL game ever.
  2. The armed, self-described “militia” yokels currently more than a week and a half into squatting in the Malheur National Wildlife Refuge headquarters in my homeland of Oregon do so in a region of the state that suffers the most harrowing winter temperatures. A week ago, nighttime lows plummeted to 18-below (cold enough to turn the occupiers into Skoal-and-jerky flavored popsicles), and it hasn’t risen much since then, and won’t until March. There’s been some talk of cutting the power to the headquarters building, and simply waiting for the unyielding, unmitigated harshness of a high-desert January to bludgeon the everloving shit out of their seditionist tantrum.
  3. I recently returned from a trip to Washington’s Olympic Peninsula to visit family for the holidays, during one of the most anomalously snowy and cold weeks of the year, with the snowline slumping down nearly to sea level, invading rainforest river valleys that are almost guaranteed snow-free throughout the winter. My soft, Hawaii-resident body whined in the face of 25 degree temperatures, atypical for a comparatively mild area of coastal Washington.

Behold, nearby Mt. Baker, one of the snowiest places on planet Earth. If winter itself had its own mountain, this would be it.

Photo: Jake Buehler

Even back in my normally balmy Hawaiian Islands, it’s now cold. And by “cold” I mean that I occasionally get the shivers waking up early in the morning with the windows open, and I don’t become a sweat-slicked heap of misery and heat exhaustion when just sitting in my home office. Basically, “cold” in Honolulu is when daytime highs top out short of 80 degrees Fahrenheit.

We tend to think these cold conditions, whether they are just a seasonal inconvenience, or a year-round way of life (like up near the poles), as being particularly insufferable for life. When the landscape is buried under five feet of Winnipeg white, the ecosystem functions very differently. Vegetation isn’t accessible to many herbivores. Predators have a minuscule pool of animals to hunt. The temperatures are too low for “cold-blooded” animals like amphibians and reptiles to stay active. Plant growth grinds to a crawl. Everything trying to scrape by in the frozen stillness seems to either be on the verge of starving or freezing to death.

The truth is, however, that while many organisms make a great effort to put up with or evade (ala songbirds flying towards the equator for winter, or mammals that hibernate) freezing temperatures…there are a minority that have embraced these glacial surroundings. Organisms that have evolved extreme levels of cold-tolerance sit at the lower boundary of what is possible for life to persist. Because of them, the coldest parts of our planet actually teem with life, even if it doesn’t appear that way during on initial impressions.

These elite lifeforms that would brush off a blizzard are often considered “psychrophilic.” The term essentially means “cold loving” and typically describes organisms that have specifically adapted to very cold conditions. This can mean that they reside their entire lives in freezing or sub-zero environments, or that they are capable of surviving and reproducing in temperatures far lower than what would turn other related species into a lifeless brick. In honor of the onset of the Northern winter, this two-part post will aim to examine some of our planet’s varied psychrophiles.

If there’s one thing absent from the pale dread of winter, it’s insects, right? Well, save for the occasional stowaway bug that invaded your house when temperatures first started to drop and has been eeking out an existence on crumbs and dirt in the corner of your laundry nook ever since like a miniature Hugh Glass. Gone are the clouds of biting mosquitoes, the buzzing of grasshoppers, and the ever-ready millions of ants eagerly helping you “clean up” any left out food. For the six-legged, it appears as though winter’s harshness is an insurmountable force.

But, if you step out and away from the warm, indoor comforts, and take a plod in the snow on a sunnier, slightly warmer day, you might find something that will surprise you.

Reverse dandruff?

These little flecks of black may look like bits of soot blown in and scattered across the snow from your neighbor’s chimney, or like a mouse that ate a whole packet of laxatives just strolled by, but they are actually living creatures. If you were to stop and observe these wee eraser shavings for a while, many would bound and rocket around, making the surface of the snow look like the effervescent, dancing top of a freshly poured glass of soda. These dark snow sprites are called “snow fleas”, but their common name is misleading.

Snow fleas (Hypogastrura nivicola) are not fleas. And, to be completely honest, they aren’t even insects. Snow fleas are a variety of springtail, which are an order of arthropods in the class Entognatha, which is very closely related to, but distinct from, the class Insecta (which contains the several million species of insects we have crawling, buzzing, and skittering all over our planet). Springtails (order Collembola) and their entognath brethren are similar to insects in having three pairs of legs stemming from a thorax body segment, but differ by having internal, closed-off mouthparts instead of having them exposed (hence the name endognath; “endo” = inside, “gnath” = jaw). Springtails also do not have wings, but many species have a tail-like “furcula”, which looks a bit like a spatula, that they can fold under their abdomen under tension by tiny hook-like structures. When threatened, they then can release the furcula and allow it to slam against the ground, catapulting them the hell out of there. Many springtails only reach about a millimeter or two in length, and a majority of species are peaceful decomposers, munching on fungi, moss, and algae in relative secrecy. They are so small and so light, in fact, that they don’t break the surface tension of water and can rest on top of a puddle (they can actually form rafts that drift back and forth across the surface of a bit of water).

Snow fleas are somewhat unique in that they are very tolerant of frankly arctic temperatures, producing a protein that works like anti-freeze to keep their motor running in the face of incredible cold. Extreme winter cold will make them inactive, but it won’t kill the little guys. Snow fleas can be found in habitats all over the temperate Northern Hemisphere at any time of year, but their notably itty-bitty nature, combined with their habit of sticking close to rotting leaf litter and soil, while also being dark in color, makes them really damned hard to spot anytime outside of winter. One is far more likely to see them once they are against a white, snowy background.

Oh, and luckily for humans interested in finding snow fleas on a late-winter jaunt, snow fleas have a habit that makes them significantly easier to see….namely, clumping together in a squirming mosh pit made up many thousands of individuals, looking like what I’m sure a spillage of pepper must look like while frying on acid. The video below gives you an idea of how unsettlingly ginormous these aggregations can be, considering that all of this footage is taken right after the nice, white, contrast-inducing snow had melted away:

If you’re starting to sweat at the idea of legions of little charcoal grill-scrapings assembling to exact revenge upon the human race, do not fear. They pose zero threat to you and yours. Truthfully, more likely than not, these mobs of minute metazoans congregate for one very specific reason: fuckin’. Female snow fleas release an attractant pheromone when they’re fertile and ready to make feet for children’s shoes. Not only does this sweet-smelling love potion bring all the boys to the yard, but the femme fleas come in droves as well. What commences is an orgy feedback loop, with more and more fertile females amassing in one place, which magnifies the strength and reach of the procreation perfume, bringing in exponentially more males fixin’ to lay microscopic pipe until their hearts give out…along with even more pungent females. The end result is a snow pit full of grand-scale debauchery and the most hibbety-dibbety this side of an ancient Bacchanalian shagathon.

Eat your heart out, Tiberius Caesar.

Gradually, the females in this sweaty, congested, literal clusterfuck become pregnant, cease making their bow-chicka-wow-wow pheromones, and abandon Bone-chella to go lay their eggs. Over the course of days or weeks, the whoopee cushion deflates as more and more snow fleas stop smashing pissers and return to their day jobs.

Huge numbers of snow fleas also come together to do something other than cumming together: to get their om-nom-nom on. The key to this is their weird life cycle. Insects molt (shed their skin) up until adulthood. Whether that means going through multiple miniature phases (nymphs) until reaching full-size, like mantises and grasshoppers…or the full-on metamorphic magic that turns grubs and caterpillars to beetles and butterflies, respectively…either way, the exoskeletal purging ceases in the adult form. But snow fleas, like all springtails, don’t go this route, and instead molt their entire life, switching back and forth between reproductive and feeding forms. One form capable of reproduction, but without the ability to feed….and one form that can eat, but can’t get it on. In times of food scarcity (like in winter), the feeding form may extend in duration, and collect in insane numbers near sources of food, which include things like tree sap, pollen, decaying leaves and other organic matter (and the fungus and bacteria doing the decaying), and nematodes.

There’s another nourishing treat that snow fleas are quite fond of, and groups of snow fleas can be seen grazing on patches of it on the snow like great herds of buffalo mowing down a rolling expanse of open prairie.

It’s red on white and cold all over. It’s “watermelon snow” and it looks like the lightly-aged remnants of a Yukon knife fight scene. Or the leftovers from when the 1st annual Rocket-powered Toboggan Race took an unexpected turn for the worst.

Packed snow isn’t quite as “low friction” at Mach 2. Lesson learned.

“Watermelon snow”, so-called for its obvious pink tinge (and, oddly, the melon-like odor it occasionally gives off), isn’t caused by gruesome spillages of blood, or chemical contaminants smeared across the wintry landscape (as was originally thought its origin). It is caused by a variety of unicellular green algae known as Chlamydomonas nivalis that grows on the surface of the snow, and down into the snow by as much as a foot.

It, like the snow flea, is a psychrophile. It’s closest relatives are typical freshwater alga, but this species likes its freshwater like Ed Gein liked his company: stiff.

The algae is common in regions that are freezing cold throughout the year. This can mean low-elevation or coastal areas near the poles, or alpine areas the world over…especially places where the snow lingers through the summer, not quite entirely melting by the time the autumn snows start again. I’ve personally seen small patches of it while hiking way up above 8,000 feet in the Central Oregon Cascade Mountains. Although the snow algae is capable of surviving the extreme cold of winter in these types of locations, it tends to hunker down and go dormant while being piled on with snow. When spring comes and the several month-long period of melting kicks off, the single-celled algae come out of hibernation and generate reproductive cells that wriggle towards the sweet, sweet life-giving sunlight closer to the surface. As the melting season progresses, the algae multiply, causing a bloom that makes the snow blush with many billions and billions of algal cells.

Chlamydomonas nivalis is a “green algae”, but is decidedly very not-green in color. The reason for this is that in addition to the normal chlorophyll pigments (the cool, colored compound that helps turn light energy into sugars), there is another reddish one: astaxanthin. Astaxanthin is pretty important in the snowy environment that the algae thrives in. As much as the icy surroundings fulfill the snow algae’s needs for low temperatures, they also are subjected to intense ultraviolet radiation. White things, like snow, reflect lots of sunlight in lots of different directions. This, combined with the bright sunlight experienced in high in mountain regions, compounds the ultraviolet radiation exposure to local organisms. The heightened level of reflected UV is enough to warrant extra eye-protection in anyone recreating in these snowy mountain environments, as to avoid the blisteringly agonizing effects of snow blindness…which is essentially a sunburn on the surface of your eyes. In the snow algae, that red astaxanthin works as a kind of sunscreen, keeping harmful levels of UV from damaging the cell by absorbing them. When absorbed, the UV radiation is converted into heat. When snow algae congregate densely in divots in the snow, the conversion of UV into heat by the algae can speed localized melting, deepening the hole. Over time, this can make “sun cups”; little, red-rimmed craters that pockmark the surface of a late summer snowbank. These rosy calderas look like some dude unzipped his snow pants to try to make “yellow snow”…but failed in the most distressing way imaginable.

“Hey, uh, you should probably see a doctor about that, bro.”

If you’re thinking to yourself, “huh, that watermelon snow looks like a delicious, syrupy sno-cone that I should taste”, you may want to take a moment to knock that shit off. Some people contest that the algae-ridden snow even tastes like watermelon, and it can be enjoyed safely. However, lots of folks report significant levels of gastrointestinal distress (read: furiously crapping) after imbibing in a bit of sanguine slush. Apparently, the snow algae produce toxic by-products that effect the human digestive tract in varying degrees, depending on the person. Some people, like I said, aren’t affected at all, or only get a bit of gut pain when they eat larger amounts of watermelon snow. Others can take just a small, refreshing portion, and later that evening they’re holed up in the John with the chunky sputters.

So, unless you are prepared to deal with the potential, unpleasant consequences, I would think it would be wise to treat any pink snow you see like the yellow version, and abstain from putting it in your goddamn mouth. Then again, I’m not going to tell anyone how to live their life. Your colon, your decisions.

“Mmmm, you can really taste the imminent ass-plosion in there!”

Snow fleas and snow algae are certainly model psychrophiles, flourishing in environments that would be devastating for many other organisms. However, there are other creatures on Earth that have freeze-avoiding powers that make the springtails and Chlamydomonas of the world look like thin-blooded snowbirds….

This post series will continue with Part 2, devoted to extremely freeze-proof insects.

Image credits: Intro image of snowy landscape (Caitlin Wynne), snow fleas on snow, pile of snow fleas, melting watermelon snow, sun cups, woman eating snow

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Australia’s “Turkey”

Today, here in the U.S., an annual tradition is underway; Thanksgiving. I sincerely hope that those of you that celebrate this festivity are hanging out with friends, family, or anyone that you care about, smartly swaddled in your best harvest sweaters. I hope by now, your unapologetically racist uncle has ceased his impassioned musings on how “all lives matter” and his declarations on how Donald Trump is “just the man for the job.” Don’t worry, the nausea will pass. I hope you’ve survived yet another round of invasive questions from perennially-seen Baby Boomer relatives about when you’ll be getting a “real” job, getting married, and having children. Take a deep breath, remember, murder is technically very much illegal. Besides, you can’t afford to go to prison. Not with all those student loans to pay off! Anyways, yeah, I wish everyone the best of luck out there.

Sure, most of us like to tell ourselves this holiday centers around ideals of family, generosity, and humbled self-reflection. But, let’s be real: the big draw for this autumnal grand event is the feast that comes along with it. Yes, modern Thanksgiving is a loving ode to gluttony…one I don’t resent for an instant. Pies, stuffing, rolls, gravy, pies, potatoes, squash….did I mention pies? But all of this pales in comparison to the main attraction, that poultry on a pedestal; the turkey.

Yes, turkey….more specifically, the domesticated form of Meleagris gallopavo, a large species of vaguely pheasant-like ground bird that ranges across much of the eastern two-thirds of the continental United States and south into northeastern Mexico. This species, along with a single close relative (the dazzlingly-colorful ocellated turkey, Meleagris ocellatus, from Mexico’s Yucatan peninsula) are the “true turkeys.” These two species make up the entirety of a distinct subfamily in the ground fowl family (Phasianidae), a large taxonomic grouping that includes chunky, chicken-like things that prefer to run rather than fly….everything from grouses to partridges to peacocks.
There are plenty of things in our world that share, completely or partially, the common name of the Meleagris birds. A venomous marine fish. Soy-based meat alternatives. West Asian countries. All these, of course, are Meleagris-style “turkeys” in name only. There are even a handful of other species of bird that are, confusingly, referred to as “turkeys” despite not being particularly close relatives of the gobble-gobble/hand tracing variety so familiar to North Americans.

One of these not-turkeys resides on the opposite side of the Pacific from Meleagris, and in the Southern Hemisphere. The animal I’m referring to is the Australian brush-turkey (Alectura lathami). With its beefy, bowling ball shape, alert and fanned out tail feathers, and naked head and neck…both saturated with colors that look like the end result of receiving a swirly in a vat of liquefied candy corn…the brush-turkey seems damn deserving of its fowl moniker.

Shit, it even wears a festive, yellow scarf. This thing is more ‘autumn’ than a fucking pumpkin spice latte.

Of course, this “turkey” can’t be quite what it appears to be. After all, this is Australia we’re talking about here; a place where “koala bears” are very much NOT bears, “marsupial cats” aren’t even remotely close to any household Mittens or Muffins, and Boston buns are certainly not “edible food.”

I mean, I like coconut too, but Jesus Christ, what is wrong with you people?

It so follows that our charismatic brush-turkey belongs to a wholly different family of birds than its name would suggest. Australian brush-turkeys, growing to as much as two and a half feet long, are the largest living members of the megapode family (Megapodiidae). Megapodes, so named for their typically thick, powerful legs and large feet, are a somewhat primitive fork of the “ground fowl” clan. Megapodes and true turkeys are both members of the ground fowl order (Galliformes), but hail from very different evolutionary lineages within that larger umbrella of relatedness. Megapodes are restricted to Australasia, with much of their biodiversity scattered through Australia, New Guinea, and many of the islands in the eastern section of the Indo-Australian Archipelago.

While the Australian brush-turkey isn’t domesticated or ritually consumed by Ozzies like Meleagris is in the States, there are unique aspects of the biology of this megapode on the antipode that are worth sharing.

Australian brush-turkeys, unlike a depressingly-large proportion of Australia’s native fauna, are actually faring quite well in the modern, industrialized era. They are a wide-ranging species, and can be found all over eastern Australia, from Cape York in far-north Queensland, down south into New South Wales. They are found in rainforest and wet woodland habitats, but can exploit drier, more open areas as well. Brush-turkeys are shitty fliers, and tend to only take to the air when absolutely necessary, preferring to use their strong legs to run around through the underbrush, pecking at insects, seeds, and the occasional fruit. Males and females look very similar, but during the breeding season, the loose, colorful wattle at the base of the neck expands and becomes more brightly-colored in males (as well as the red skin on the head). The male’s wattle gets big and floppy enough during this time of year that it pendulates wildly as the bird runs, like a geriatric scrotum….which is imagery I’m sure you didn’t need exposure to today. Again, I hope that by the time you read this, you’re done with the dinner portion of the holiday….

But perhaps the most interesting thing about Australian brush-turkeys is how they bring little brush-turkeys into the world. They, like all megapodes, have highly divergent reproductive practices.
Megapodes are also known as “mound-builders” or “incubator birds”, which is in direct reference to their massive nests. Unlike all other birds, megapodes do not incubate their eggs by popping a squat on them and keeping them at just the right temperature with their body heat as they mature. Megapodes, after grunting out a hard, pearly litter, bury them….like a cat burying a turd. The eggs are sandwiched above ground in the middle of a seemingly excessive quantity of organic material; in the Australian brush-turkey, the mounds can be chest-height and roughly as long as an SUV. It depends on the species, but in many megapodes, the eggs rest in the center of the mound, with rotting vegetative matter below the clutch, and dirt and sand covering on top for insulation. The mound functions as an incubator, with heat coming from underneath from the continually decomposing compost, and the denser layer on top keeping the heat contained. Once completed, the male partner plays the important role of the thermostat, testing the temperature inside with probes of its beak, and adjusting by either removing or adding material to the mound, making sure everything is just right on the inside.

Yes, that’s right, a “turkey” makes an oven for its own eggs, and periodically tests the temperature of its clutch with a built-in thermometer to make sure the precious cargo doesn’t get over-done.

“Mmmm, that smell of decay is getting stronger. Looks like it’s almost ready!”

This inevitable habit of large-scale construction of reproductive monuments becomes a bit of a nuisance when the brush-turkey is confronted with the manicured backyards of suburban Sydney and Brisbane. Brush-turkeys are adaptable birds, and while they don’t prefer sharing habitat with humans, encroachment into their home range has made interactions between city-dwelling Australians and these birds unavoidable. Once a brush-turkey has wandered into a yard, picked out a suitable plot, and started meticulously gathering up leaves and dirt in a fledgling pile…it’s kind of impossible to get them to knock it the fuck off. Brush-turkeys, like Richard Dreyfuss painstakingly crafting a mashed potato diorama of Devil’s Tower in Close Encounters of the Third Kind, will obsessively build their creations until they are complete. Even if the mound is destroyed during construction, they will stubbornly rally their efforts and start over. Again, and again, and again.

Because of this, brush-turkeys can be the nightmare of anyone with anal retentive views on landscaping. Gardens? It can be scrapped for mound material in two days or less. Enjoy having bark mulch? Too bad. It all goes to the pile. The pile is all. The pile is Life.

Pictured: An animal that doesn’t give a single, limp-dicked fuck about your zucchinis

As human populations grow, and more and more interactions between brush-turkeys occur, rather than responding to frustration with violence and extirpation, various governmental and conservation agencies have advocated some measure of coexistence with this…er….industrious…bird. Seriously, there are websites devoted to tips for dealing with brush-turkeys. Some work-arounds include just acknowledging that gardens and planned backyard spaces are a no-go, and just going ahead and planting natural vegetation. Another approach is just having a compost pile already going in the yard, so when a brush-turkey waltzes by, it’s tempted to just use what you’ve already started for it rather than starting from scratch (literally).

Given that everything turns out OK on the incubation side of things, the eggs will eventually hatch. However, unlike every other type of bird, megapodes hatch under unique difficult conditions….namely, that they are buried under potential hundreds of pounds of rotting vegetation. Luckily, megapode chicks are “superprecocial”, meaning that they come into the world rippin’ and ready to go, in stark contrast to the pink, helpless, larvae-like “altricial” hatchlings that you typically see in things like robins. Megapode chicks are typically fully-feathered, with eyes fully open, and able to run, hunt prey, and sometimes even fly right out of the gate. This is like if human babies rocketed out of the womb, and promptly teetered out of the hospital, bitching about being late to work, lit cigarette drooping from their lips.
Because megapode chicks need to get the hell out of their eggs and scramble their way through an ocean of rotten wood chips so they can breathe, they don’t have the luxury of slowly picking away at their shells from inside like most birds. Megapodes don’t have an “egg tooth” with which to chip away a hole in the egg’s shell. Instead, they use their heavily-muscled, oversized feet to claw their way out.
That’s right, megapode chicks fucking round-house kick their way into the world.

This is the fluffy little bastard that keeps Chuck Norris awake at night.

So, this Thanksgiving, I give thanks to Australia, for providing such a bizarre, badass take on the “turkey” that I can admire (luckily, for my garden) from several thousands of miles away.

Image credits: Intro image of brush-turkey, brush-turkey #2, Boston bun, brush-turkey on nest mound, brush-turkey scraping vegetation, brush-turkey chick

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Mesmerizing Marine Mimics: Ichthyo-invisible

This post is the sixth in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be. The first entry in this series goes over some fundamental introductory concepts and definitions regarding mimicry in general.

Blending in with your surroundings to the point of near invisibility is a trick that gifts huge benefits.

I know that at least for me, there have been moments in my life where I wish I could have become functionally invisible to those around me….situations where just fading into the background, completely and utterly, would have provided me instantaneous relief. Like that time in high school basketball when I scored on the wrong basket. Or that time when I was 16 and had to get my palate extended prior to getting braces, and for more than a week, I walked around with a space between my two front teeth wide enough to steer a barge through. Or that time I chickened out in the middle of asking someone to senior prom, telling her that she could go with me if no one asked her by the time of the dance “or whatever” (which is both cowardly and implicitly insulting, good one, teenage me!).
….ok, you know what? How about high school, as a whole, being what I’m thinking of here then. The entirety of high school was a bit of nightmarish cringefest and if I had the ability to Hollow Man my ass out of the visible spectrum, I’d have jumped on that shit.

I was not so fortunate, but there are members of the animal kingdom that can vanish from sight, becoming indistinguishable from the backdrops of their habitats….and they have far better justifications for this power than dodging social embarrassment and minor psychological scarring.

This biological phenomenon – evolving an appearance and/or behaviors that make you very hard to detect within your environment – can be broken down into two main varieties. The first is simple camouflage. This is where texture, color patterning, shading, and other visual properties that an organism has make it blend in seamlessly with the uninteresting crap in its general vicinity; dirt, rocks, foliage, whatever. Camouflage makes critters’ bodily outlines disappear, and their image becomes disrupted and lost in a sea of unbroken similarity, but they remain…hidden in plain sight like one of those visages lurking beneath the surface of an ever-frustrating-as-fuck Magic Eye illusion. The purpose of camouflage is to completely destroy the “object detection” potential of a casual glance, allowing the sneaky bugger to sit tight, unnoticed.

The bride looks lovely! It’s a shame her bridesmaids never showed up though.

Sharing a lot of kinship with camouflage is “mimesis”, which is a variety of mimicry where an organism evolves to closely resemble a very specific benign environmental object to avoid detection. The difference between camouflage and mimesis is subtle, but nonetheless quite important….in the same way that saying “dinner was greatly enhanced by the presence of my favorite dish, Grandma, and an antique tablecloth” is basically harmless, but the minutely different “dinner was greatly enhanced by the presence of my favorite dish, Grandma and an antique tablecloth” will likely raise a few red flags.

The difference becomes a bit more apparent when you look at examples of each category. The famous peppered moths, when laying flat against a tree trunk, blend in expertly with the pattern and color of the bark. The spots and stripes of leopards and tigers, respectively, help break up their outlines, allowing them to slink slowly after prey, fading visually into the tall grasses and undergrowth of their tropical home. These are both camouflage at work.
In contrast, a grasshopper that mimics the color and shape quite specifically of a dead, crispy, brown leaf to keep off the radar of hungry predators is using mimesis. Stick insects are also mimetic, and imitate the shape and movements of plant twigs and leaves to keep from being noticed.

Essentially, if you are using camouflage, you fade in with the surface of a twig or branch. Or you are hard to see against a backdrop full of twigs and branches.
If you are using mimesis, you, as a whole creature, resemble the very shape of a twig or branch.

These are two closely related evolutionary strategies, but with slightly different executions. Camouflage and mimesis both allow organisms to hide from sight without literally hiding.

Pictured: Homer illustrating something that is effective, but neither camouflage nor mimesis.

Camouflage and mimesis (sometimes generally referred to together as “crypsis”; from the Greek ‘kryptos’, meaning ‘hidden’) is easily the most common form of mimicry in nature, both in terrestrial and marine environments. In the ocean, the number of examples are staggering. Crinoid shrimp virtually disappear when they crawl among the branches of their home feather star. Octopus (and many other cephalopods), with their exquisite active camouflage, can vanish in an instant into a mind-blowing variety of backgrounds, Peeta Mellark style, making them the world champions in the game of “Oh Shit! There’s My Ex! Hide and Avoid the Upcoming Uncomfortable Interaction!”. Numerous species of open-water fish use countershading (light colors on the belly, dark on the back) or reflective, shimmering scales to make them harder to place in their vast, blue, light-rich environment.

Since there are so many examples of marine crypsis to choose from, I’ll make it easy and do a skirting approach on a set of cryptic fish, particularly some of the more impressive ones. Some of these fish I’ve already talked about in earlier posts in this series. Frogfish, for example, use elaborate camouflage to dupe their unsuspecting prey. Outside of frogfish, there are two main groups of marine fish that have really pinned down the camouflage and mimesis thing.

The first are the Syngnathiformes, an order of fish that includes fairly widely-familiar groups like seahorses and pipefish. But seahorses and pipefish only represent a subset of the diversity of this order, and there are plenty of families of Syngnathiform fish full of bizarre representatives. The Syngnathiformes all share skinny, stretched-out bodies encased in bony rings, making their skeletons look like a cement Slinky. They also tend to have tiny mouths perpetually pulled out in a pucker. But don’t let their cute, tubed snoots fool you; the Syngnathiformes are a guild of the most skilled ambush predators under the waves, using their weird, ridiculously-shaped bodies as mimetic devices amongst seaweed and other vegetation, obscuring their presence and allowing them to slowly approach delicious morsels, sucking them up one after another. Seahorses and pipefishes in particular use a unique feeding mode called “elastic recoil” feeding, in which the muscles that rotate the head upwards remain contracted, but release at just the right moment, causing the head (and mouth) to swing upwards in a blinding uppercut…straight into an unwitting prey item.

Syngnathiformes contain some of the most hardcore hard-to-spot mimetic fish in the ocean, and one small family from the tropical Indo-Pacific, the ghost pipefishes (Solenostomidae)…named for their uncanny ability to “ghost” out of the realm of visibility, illustrates this best.

Here’s a pair of robust ghost pipefish (Solenostomus cyanopterus) looking so much like fragments of reddish seaweed that it, frankly, pisses me off:

Yes, these are fish. Somehow.

Think I’m bullshitting you? Have a look at this roughsnout ghost pipefish (Solenostomus paegnius), looking like that gross splinter of celery that’s been stuck underneath your fridge for a few weeks, all covered in dust bunnies and mold. But it’s definitely an actual fish. See, it totally has an eye and everything!

I propose a new common name: fuzzy jade ninja-fish

The harlequin ghost pipefish (Solenostomus paradoxus) adds a dash of Lewis Carroll hallucinatory flair to unbeatable seaweed-mimicry superpowers, resulting in an animal with body proportions that don’t seem possible, adorned in mescaline-inspired colors.

It looks like a letter in an alien alphabet that has come to life.

Ghost pipefish depart so dramatically from the standard fish body plan that half the time, it doesn’t seem possible that these are indeed fish and not little fragments of algae adrift along the sea floor. It doesn’t help that the deceptive little bastards take great care to move deliberately in the slow, nearly accidental-seeming fashion of seaward in the push and pull of the current, tens of yards below the surface.
I generally have a difficult time trusting any animal if the location of its butt cannot be easily determined in several seconds of cursory inspection. I can hardly even discern where the main axis of the body is on ghost pipefish, so just their continued existence kind of fucks me up.

What else are they trying to hide? You know, other than every physical feature that makes them recognizable as an animal.

The Syngnathiform mimetic madness doesn’t stop with the ghost pipefish. There are also the “shrimpfishes”, which belong to the family Centriscidae. These are small, silvery, fish with long, pointed beaks and stumpy, tapered bodies shaped, unsurprisingly, like a shrimp. They range across the tropical Indo-Pacific, and many species (like the razorfish, Aeoliscus, shown below) frequent shallow, inshore waters, typically in areas with plenty of seaweed and almost always in tight-knit schools.

Also, did I mention they swim with their faces pointed straight down? Like…completely vertical. As in, like a collection of mini-flagpoles.

Ugh, god, we get it: you can do a handstand. Big fuckin’ deal.

This isn’t because evolution accidentally rotated the shrimpfish an extra 90 degrees in the Photo Editor of Life. This habit of swimming skillfully in the horizontal plane, with the body tilted ass-skywards like the nose is tipped with lead, is intentional. At any point, the shrimpfish can straighten out and scoot along like any other self-respecting fish, facing the direction of travel….but for much of its life, it takes the inverted route, bobbing and dancing in concert with its little pack of like-oriented weirdos.

It’s thought that this parading and pitching around like a living video game graphics error is a means of mimicking the spines of sea urchins, which are common in roving herds that munch their way across the shrimpfish’s vegetation-rich home. Shrimpfish are commonly found aggregating among the long, black spines of urchins, their centrally striped flanks resembling the needle-sharp lances that they flit between, rapidly beating their tiny, spatula-shaped fins against the lurching surge to keep themselves erect and convincing.

Of course, no examination of the surreal inconspicuousness of the Syngnathiformes would be complete without mentioning the seadragons.

Seadragons are a type of pipefish (although their heft and body shape make them look like seahorses, which are different subfamily), and are only found along the cooler coastal regions of Australia. There are three species, divided into two genera; the single variety of leafy seadragon (Phycodurus) and two species of weedy seadragon (Phyllopteryx). They are a bit larger than just about all seahorse species, but the largest seadragon only reaches about the length of a human forearm. They swim slowly among the seaweed, snapping up tiny crustaceans as they rock and lethargically teeter along through their underwater forest habitat. So, being pretty normal by pipefish standards, they aren’t exactly the terrific, marine monstrosities their common name might suggest.

If this is what you were expecting, I’m sorry.

The “leafy” breed of seadragon, Phycodurus eques, ranges along the coastlines of Western and Southern Australia. It is covered from head to tail in large, elegant, green-yellow fleshy extensions that mimic the fronds and branches of the seaweed that it floats amongst. These remarkable, delicate lobes are all for decoration, however, and the leafy seadragon is entirely propelled by tiny, hardly visible, translucent fins up near its “head” and down along the tail. Since these fins’ constant beating is hard to observe, the seadragon appears to leisurely drift along, its body core still and stiff, powered solely by its own will.

A dragon that soars with no wings? Falkor is that you?!

Unsurprisingly, these raggedy little guys and their built-in ghillie suits are a popular attraction in aquariums around the world, and have become the marine emblem for the state of South Australia.

Their cousins, the weedy seadragons (Phyllopteryx), inhabit much of the same region and habitat. Weedy seadragons have much fewer camouflague skin lobes, making them looked like a freshly pruned version of their leafy counterparts. They are also darker and more variable in color, and the lobes more closely match the leaves and bladders of kelp than the thin branches of other types of seaweed. Weedy seadragons also manage to look even more alien and creepy than the leafy seadragons. Leafy seadragons at least look like seahorses that may have gone too crazy in regards to accessorizing, but weedy seadragons look nothing like their adorable seahorse brethren. Weedy seadragons, with their cartoonishly elongated snouts and crooked bodies, look like the seahorses’ sad, reclusive uncle with scoliosis that only comes around to borrow money for enigmatic reasons and to make unsettling comments about the underage butterflyfish next door. Weedy seadragons are what you get when Salvador Dali tries to create a depressed balloon animal.

*high-pitched wheeze of self-loathing*

Just this year, a second species of Phyllopteryx was discovered off the coast of Western Australia. It appears to occur in somewhat deeper water than the other two species of seadragon, and due to its rich red coloration, it has been dubbed the “ruby” seadragon.

The second group of fish that have mastered the art of the low-key existence are the Scorpaeniformes, a massive order of fish that includes everything from rockfish to sculpins to scorpionfishes (the last of which I addressed in an earlier post in this series). A large number of species in this order are equipped with venomous spines and/or top-notch ambush predators that hunker down on the sea floor and wait for prey to make the fatal mistake of swimming too close to their eatin’ end. The lie-in-wait hunting strategy is one that requires a great deal of patience, but also the ability to be completely inconspicuous. Because of this, many stationary ambush predators in this order have evolved camouflage to help them sink in with the visual environment.
The scorpionfishes (family Scorpaenidae) are the quintessential badasses at this usage of crypsis (with the exception of boldly patterned, active swimming forms like lionfish), and the level of diversity within this family is tremendous, contributed from literally hundreds of species.

One of my favorites in this group are the Scorpaenopsis scorpionfishes, which are found all over the warmer seas of the Indo-Pacific. It’s perhaps a blessing that these fish are so adept at staying out of sight, because with their upturned faces, made up mostly of a perpetually frowning, toad-like mouth and a pair of comparatively tiny eyes perched high on the head, and squat, brick-shaped bodies, scorpionfish are about as homely as a fish can get.

Now, imagine you’re a small fish on the reef playing the lifelong game of Spot the Scorpaenopsis, and the scene below encompasses your fishy field of vision…

It’s like “Where’s Waldo?”…if failing to find Waldo meant getting eaten alive

Chances are you won’t see the tasseled scorpionfish (Scorpaenopsis oxycephala) at all when you pass right over him, but he’ll see you. He’ll see you just damn fine….

Scorpaenopsis scorpionfish tend to go for the algae-covered/rocky substrate type of look, which, cool as it is, is outmatched by the concealment efforts of another genus of scorpionfish.

Meet Rhinopias, an arm of the scorpionfish family line that has converged heavily on the frogfish’s camo game:

That’s one grumpy clump of seaweed.

Scorpionfishes often aid the effectiveness of their disguises by positioning themselves in places of favorable topography. Lumpy forms that look like rocks that haven’t bathed in a while frequent silty or turf-algae rife areas with plenty of rocks. Frilly, colorful varieties seek out seaweed or coral that goes with their outfit. But what if you need to blend in when there’s nothing around you other than flat, dull sand?

The crocodilefish (Cymbacephalus beauforti) seems to have figured that one out. Crocodilefish are flatheads (family Platycephalidae), a group that is somewhat close kin to the scorpionfishes and found widely across the Indo-Pacific region. Crocodilefish in particular are all about shallow reef habitats, and rarely stray deeper than a dozen meters. While they are capable of hiding from prey in rockier habitats, they gravitate towards sandy, open areas, where they can lay out flat.

And I’m serious when I say flat. Crocodilefish look like a muskellunge in a vacuum-sealed storage package.

There, they are effective ambush predators, visually inseparable from the surrounding sand and pebbles. Unlike many scorpionfish and scorpionfish-adjacent fish like this, the crocodilefish is of significant enough heft that most fish on the reef have reason to worry about traversing over the submerged deserts this creature haunts. While larger species of flathead do exist, the crocodilefish routinely achieves about the size of a baguette.

It’s name of ‘crocodilefish’ is well-earned, not only because of its weirdly reptilian mug, but also its merciless appetite. Using the same blinding speed of other scorpaeniform ambush predators, the crocodilefish opens and extends its jaws so fast that it briefly creates a strong suction force, yanking prey down the inside of its long, long face well before the victim releases what’s happened.


Here lies the ‘tail end’ of the post series…

This post on mimesis and camouflage is the sixth and final entry in the marine mimicry post series, a collection of entries that delved into everything from toxic flatworms (and the diversity of mimics “inspired” by them), opportunistic fangblennies, and practically unbelievable carbon copy imitations that not only bridged species lines, but sometimes entire phyla.
Mimicry has evolved with numerous functions, and in multiple evolutionary contexts, in just about every major lineage found in our oceans. Whether it’s used to acquire food or gain protection, deception about one’s basic identity is one hell of a good way to get the job done.

Image credits: Intro scorpionfish, robust ghost pipefish, roughsnout ghost pipefish, harlequin ghost pipefish #1, harlequin ghost pipefish #2, shrimpfish, leafy seadragon, weedy seadragon, tasseled scorpionfish, Rhinopias, crocodilefish, crocodilefish with prey in mouth

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Mesmerizing Marine Mimics: Wolves in Sheep’s Clothing

This post is the fifth in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be. The first entry in this series goes over some fundamental introductory concepts and definitions regarding mimicry in general.

Animals can be real dicks.

Hermit crabs congregate solely to aggressively covet bigger and better shells, eventually leaving at least one or two crabs forcefully foreclosed upon and left to wander the beach, squishy, defenseless, and homeless. Lovable dolphins routinely slaughter porpoises that stray too close to their turf, but not without sexually assaulting and mutilating them first…you know, just because. Male mallard ducks are such a charming combination of unhinged sexual aggressiveness and zero regard for consent that females of the species have evolved vaginal labyrinths to stymie the effectiveness of the penetration of the corkscrew Johnsons of their feathered assailants. The natural world is chock-full of organisms being outright bastards to one another, because life is rough, and sometimes those that are more Shkreli than Gandhi scam and abuse their way to evolutionary success. In the river of Life, the fork that yields survivorship, high fecundity, and a strong genetic legacy is typically navigated by a very special variety of watercraft: the douche-canoe.
The phenomenon of mimicry is certainly not immune from nefarious applications, and many taxa use mimicry to gain the trust of other species, only to con them…potentially out of their lives. This flavor of mimicry, where an organism mimics a species perceived by others as benign (or even beneficial) to gain access to resources (food, mating opportunities, etc.), is called “aggressive mimicry.” I’ve brought it up briefly before in this post series, in particular when talking about fish that use lures to persuade prey to practically swim into their waiting gobs, like with the decoy scorpionfish or the frogfish. However, there are some marine critters that take the cake when it comes to the Machiavellian style of mimicry. The fish that this blog post will explore shamelessly engage in as much sociopathy, brazen laziness, selfishness, and manipulative scheming as you’ll find this side of an episode of “It’s Always Sunny in Philadelphia.”

Take, for example, the hamlet fishes (genus Hypoplectrus), a collection of small, typically brightly-colored groupers found in the tropical West Atlantic and Caribbean. Hamlets are ridiculously tiny by grouper standards, considering the largest members of the family can grow as large as a smart car, but are nonetheless incredibly competent, voracious predators, snapping up small crustaceans as they patrol the maze of the reef. Sneaking up on wary prey, and keeping it wonderfully oblivious until the very last moment, is a difficult task for any predator, so it pays to be able to get close with minimal effort….and it’s thought that a few species of hamlet have managed to do just that.

The living police car beacon light below is the blue hamlet (Hypoplectrus gemma). It, like the other hamlets, grows to a handful of inches and has a face only a mother could love.

I haven’t seen a hamlet this blue since the Prince of Denmark fondled a jester’s skull

Hypoplectrus gemma just so happens to share its Caribbean and Gulf of Mexico geographic range with another fish, the blue chromis (Chromis cyanea). Chromises are damselfish (family Pomacentridae) and have a diet generally consisting of tiny, suspended particles of food in the water column. While they can be cantankerous, bitey little pricks in regards to defending their territory and eggs from other fish, damselfish, with their tiny mouths perfectly suited to pecking at planktonic flakes, aren’t exactly the predatory scourge of the reef. The blue chromis is no exception.

Pictured: Probably not a shark

For this reason, the small crustaceans on the reef (shrimp, crabs, and the lot) don’t have much to fear from the blue chromis. What they do shit their ten-legged pants over are hamlets, which are ever-hungry Bubba Gump addicts with (much like other predatory fish) a mouth that sucks harder than a DVD of “Transformers: Age of Extinction” taped to a Bissell. If they sense the clear presence of a hamlet, wiser crustaceans make sure their exoskeletal asses are well hidden in the smallest grooves and pores in their coral surroundings. So it’s a good thing for the blue hamlet that it, as you may have noticed, looks remarkably similar to the comparatively harmless blue chromis. It’s thought that to the common crustacean on the reef, with simple eyes unable to discern fine details, the blue hamlet is basically indistinguishable from a blue chromis….allowing the hamlet to leisurely approach its crustacean prey without raising any red flags. From the perspective of the shrimp, an inoffensive little damselfish, barely worth considering, is just drifting into its personal space…like a fly casually landing next to you on a park bench. You may not even register that the fly is inches away from your leg. Why would you? Flies aren’t dangerous, incredibly common, and there’s not really any reason to notice them at all. If that fly promptly swallowed you in one tremendous gulp, you wouldn’t be able to say you saw it coming. The same goes for the shrimp and the “damselfish” that floated over to say hi. It’s possible that taking advantage of the reputation of the blue chromis as an inconsequential wallflower allows the blue hamlet to cruise through its predatory life with the difficulty setting on “easy”, feigning innocence long enough to straight up murder meal after meal after meal.

I say it’s “possible” that this is the case, because no one, to my knowledge, has actually confirmed behavioral mimicry in this species of hamlet, and the level of mimicry in blue hamlets (and a number of other hamlet species that are proposed to mimic different types of damselfish) appears to be limited to severely suspicious similarity in color and appearance between the mimic and the model. Well, with the exception of one hamlet species. The butter hamlet (Hypoplectrus unicolor) is an apparent mimic of the four-eyed butterflyfish (Chaetodon capistratus)…a fish that you may remember from the last post in this series as being an automimic, flashing confusing eye spots when confronted with danger (yes, the model for the butter hamlet’s mimicry is in fact another mimic). Butter hamlets not only wear their model’s colors, they also follow the butterflyfish around the reef like a puppy in an attempt to blend in more effectively (possibly appearing to be the butterflyfish’s mate). The hamlet also uses this convenient opportunity tagging alongside the butterflyfish to try and suck up as many crustaceans as possible….in fact, about half of all the hamlet’s predatory strike attempts are made when it is using its model as a unwitting wingman. The butter hamlet apparently hardly goes through the effort of trying to eat unless it is actively mooching off the presence of its model to further dupe its prey. These fish are about as principled as the guy who fakes homelessness to gain access to a food pantry so they can pocket as much grub as possible before dashing out the door.

It’s one thing to fly under the radar as an uninteresting, benign reef fish in order to score your dinner. It’s something entirely different to convince your meal that not only are you harmless, but that you are their friend. That you are there to help.


Just a big ol’ pot of altruism you are. Honest….

Ocean ecosystems are a cauldron bubbling over with life: fish flitting and spawning everywhere, countless organisms living, pooping, and dying, vast fields of pelagic plankton converting carbon dioxide and nutrients into grand scale blooms. The sea is like a well-used, never cleaned, fraternity hot tub at the end of a long, sweaty, rambunctious summer; crusty, high in biodiversity, and swimming with critters you’d rather pretend aren’t in there. Life, just by existing in this saline soup, tends to have other life invade, infect, and coat it liberally; there is no escape. External parasites are pervasive in the marine realm, and cling to the outside of larger animals with a stubborn, death-grip of permanent stickiness only outmatched by what fucking glitter does whenever it comes in contact with human skin. These irritating stowaways, often times blood-sucking crustaceans like sea lice and roly-polies that live like leeches, aren’t exactly an appreciated gift of the sea by the animals that have to deal with their shit. Parasites drain precious energy and resources along with the blood they sip, and in the unforgiving wild, having an assload of freeloaders drinkin’ up your go-juice is a fine way to have your anemic keister end up deader than it was last week. Simply put, parasites end up weakening their hosts…so it behooves the besmirched, non-consenting smorgasbords to have them removed. Oh if only such a means existed…

Stepping up to the plate is a fish that specializes in making itself incredibly useful to the other fish in its community; the cleaner wrasse (Labroides). Labroides wrasses, of which there are five species, are known as “cleaner fish” (which is a role held by more groups of fish than just these wrasses), meaning that they prune and pick parasites off the scaly outsides of other fish. Cleaner fish don’t do this bit of public service as part of getting their Goody Two-shoes Badge in the Neptune Scouts or something…they get the bulk of their nutrients from the parasites and mucus layer on other fish. The tiny, vibrantly-colored, finger-shaped cleaner wrasses are widespread, common cleaners in tropical Indo-Pacific reef ecosystems, and many species of fish across the region are quite familiar with their grooming-focused diet. Not only do reef fish tolerate the little buggers coming up and nipping at their flanks (oxpecker style), but they will actively seek them out. Cleaner wrasses (along with other cleaner species) will typically hang out in specific areas on the reef that quickly become “cleaner stations” where scores of fish, of all taxonomic stripes, congregate to get all spruced up. The wrasses will bob and dance in a distinctive fashion to get the attention of potential “client” fish, and to advertise that the station is officially open for business. A client fish will usually signal to the resident shopkeep’ that they’re ready to be pampered by making a slow approach, articulating and tilting their fins and body, and opening up their mouth. The wrasse gets the message that this much larger fish is providing a meal, not looking for one, and it (and others) descend, darting around the outside, gills, and in the mouth of the client, clipping off whatever parasites they can find (along with some mucus and dead tissue as a bit of bonus flavoring).

“Is that…a tip jar? Are you serious? I’m literally feeding you two right now.”

Nasty, toothy, predatory fish like eels and needlefish, which can easily snap up the cleaner wrasse in a blink, patiently allow the world’s hungriest dental hygienist to get halfway into their throats to make everything sparkle. But, they trust that the benefits of having these eager exterminators going to town on their afflicted areas greatly outweigh the drawbacks of neglecting to take an easy meal. The clients trust they aren’t being taken advantage of, and the cleaner wrasses are confident they won’t be gobbled up while on the job…and this little symbiotic economy trucks on and on in near-harmony.

Well, kind of. Here’s the part where a third party throws a giant, douchey wrench into the mix.

Take a look at this cleaner wrasse:

This is Labroides dimidiatus, the bluestreak cleaner wrasse. It is common on reefs ranging from East Africa all the way out to French Polynesia in the South Pacific.

Now, look at this next fish, and look closely, because this fucker is the reason we can’t have nice things:

The fellow with the self-satisfied little smirk up there is not a bluestreak cleaner wrasse. It’s not even in the genus Labroides. Hell, it’s not even a wrasse. This fish is a variety of combtooth blenny, and therefore hails from a completely fucking different family from the cleaner wrasses. It’s known as Aspidontus taeniatus, the false cleanerfish, and as you may have figured out by now, is a convincing mimic of the bluestreak cleaner wrasse, just based on physical appearance alone.

‘But why mimic a cleaner wrasse?’, you may be thinking. Are the wrasses poisonous? Does looking like a cleaner wrasse allow them to escape predation? The answer to that is technically yes, but not for the reason proposed in this hypothetical train of thought.

Think of it this way: cleaner wrasses are popular. Among reef fish, they are highly-regarded. Trusted. Their particular set of skills and associated reputation has earned them the distinct privilege of unlimited access to piscine personal space. Surely, if another species were to disguise themselves as one of these pillars of the community, they would be able to get all up in larger fish’s business without issue. They could get as close as they wanted, and do whatever they wanted, all while never being hassled by predators.
While this initially sounds like a typical case of Batesian mimicry (mimicry to save one’s own ass from being eaten), and it mostly is, the false cleanerfish just couldn’t leave it at that. False cleanerfish, on occasion, exploit having the keys to the kingdom and decide to skim a little action off the top…and by that, I mean they tear chunks of skin and flesh out of their “clients” as a small tax for their delightful companionship.

Yes, this blenny capitalizes on the trust of its “clients” by not only being perceived as too damned important to be eaten, but also by periodically nibbling on these same fish like they’re big, living, traveling pantries.

False cleanerfish pull this off by managing to imitate the “wrasse wriggle” of their less bitey model in the middle of the cleaning station. When a client fish poses for some, er, oral service, the cleanerfish glides on over….probably giving itself a disquieting chuckle as it closes in. If the mood suits it (something that occurs perhaps one fifth of the time), the false cleanerfish then uses this golden opportunity to open its dainty little mouth, and drive a pair of hooked fangs up into an exposed sheet of fin from their seat in the lower jaw. This grand display of violent double-crossing apparently works best on juvenile client fish, as the adults have had a lifetime to figure out the subtle differences between the real deal and the filet-o-fraud that has a good chance of doing nothing but leaving behind a bloody, regret-shaped hole in a fin. It’s kind of like how the Internet looks very different to someone using it for the first time, and someone who’s been immersed in it for well over a decade: to a first-time user, sidebars and headers are full of a dizzying array of flashing and total convincing notifications of prize winnings you (somehow) are bound to receive (one click ahead!) and panicked, 5-alarm warnings about computer viruses you need to eradicate RIGHT NOW (…also one click ahead)….but to the Internet veteran, they’re savvy enough to recognize that these are all skeevy, predatory landmines littering a road to nothing but malware hell and digital herpes.
Many adult client fish have been burned by this used car salesman of the sea once or thrice before, and won’t let the little prick get close enough. But wide-eyed youngsters, not yet jaded and suspicious, are more likely to be successfully victimized.

Of course, fish don’t exactly write scathing Yelp reviews of their disappointing, painful encounters with these incompetent, overly-aggressive parasite-removers to tell other fish to beware and take their business elsewhere. Word doesn’t get around. So, if the false cleanerfish isn’t overzealous with the frequency of its biting behavior, there should always be a crop of innocent minors to teach, in a phenomenally direct fashion, that the world exists to completely fuck you over.

Then again, such client fish could have it worse. They could be damselfish. Specifically, damselfish that have to deal with the nightmarish psychological terrorism provided by the dusky dottyback (Pseudochromis fuscus).

Dusky dottybacks are found in the rich, vibrant, hyper-diverse coral reefs of the eastern Indian Ocean and southwestern Pacific and off the northern coasts of Australia. They, like all dottybacks (family Pseudochromidae), are diminutive, active predators that zoom around the reef and make a living fitting whatever they can into their insatiable jaws (usually crustaceans and tiny fish).
They also come in a wide variety of colors. Dottybacks in general exhibit eye-frying levels of super-saturated color (just take a look at the orchid dottyback) and there is great diversity in this coloration….but this tends to be between species of dottyback. Dusky dottybacks have distinct color morphs, ranging from yellow, to brown, to pinkish, to orange, and gray.
Conveniently, different color morphs appear to match up with the coloration of whatever species of damselfish (Pomacentrus) the dottybacks hang out around….which also tends blend in with the color of the coral backdrop in that area. Yellow damsels (like the lemon damselfish, Pomacentrus moluccensis) hanging out in yellow-y reef areas are accompanied by yellow-morph dottybacks. Brown damsels (like the Ambon damselfish, Pomacentrus amboinensis) in duller reef habitats also have brown-morph dottybacks loitering nearby, and so on. While blending in with the coral reef benefits both damselfish and dottybacks by making them less likely to be seen by big, fishy eating-machines and gobbled up like a handful of Skittles, the angle that the dottyback ends up working involves something far more sinister than just staying out of danger.

Really? The thing that looks like Steve Buscemi reincarnated as a betta isn’t trustworthy? You don’t say…

You see, being the same color as the coral around you is dandy and all, but from the dottyback’s perspective, the real magic is in looking like the damselfish that you keep company.

Dusky dottybacks blend in among their dim-witted damselfish schoolmates effortlessly. The damselfish accept their likewise-colored comrade as one of their own, and hardly pay the dottyback any mind. Sure, damselfish are notoriously territorial (towards their own species and others), but when their watery, slack-jawed gaze sees the dottyback in their midst, the damselfish may as well be looking in a mirror. The damselfish sees just another member of its tribe, completely failing to comprehend that a silent agent of Death has infiltrated their ranks.
The dottyback isn’t wearing its finest damselfish suit to conduct an undersea drug sting, or to romance a damsel-lady from the other side of the tracks (which is pointless, son; you come from different worlds! A damsel can’t love a dotty! She’ll eventually find out your secret, and while she can accept you for who you are, she’ll be crushed that you lied the entire time! It’ll end in heartbreak! HEARTBREAK!)….no, none of this.

The dottyback is there to stalk. To hunt. To feed. Not on shrimp, or mollusks, or a crop of sea squirts.
The dusky dottyback is there to kill and eat young damselfish. Yes, like some monster out of one of the more fucked up Grimm fairy tales, this scheming fish passes itself off as the adult neighbors (and, less likely, parents, aunts, uncles, etc.) of clueless damselfish children purely to get close enough to dine on their tender baby-flesh.

A 17th-century depiction of the patron god of dottybacks, Kronos, om-nom-nomming the everloving shit out of a baby

Dusky dottybacks hardly even register in the minute-to-minute perception of juvenile damselfish and their adult counterparts, and certainly aren’t considered a threat…until it’s way, way too late for the Pomacentrus pre-schoolers.

This cunning method that allows remorseless butchering of the small and naive, works out great for the dottyback, stealthily filling its belly, and increasing the average age of its host damselfish collective, in plain sight…but the mind-fuckery experienced by these young damselfish must be beyond compare. When the pedophagous Judas rolls into town, and you can’t trust any local adults to not fucking eat you when you aren’t paying attention, life must be a waking night-terror.

But wait, it gets better. The different color morphs of dusky dottybacks that target specific varieties of damselfish aren’t locked in. The dottybacks can actually change their color, and move back and forth between color morphs….allowing them to mimic and prey upon the kids of multiple species of damselfish. A brown-morph dottyback can turn into a yellow-morph dottyback (and vice versa), for example, in just a couple weeks after moving in next door to some yellow damselfish. Once enough of its brown pigment cells in its skin convert to yellow pigment cells to where it matches the color of its damselfish neighbors, the dottyback’s pride-n-joy predation success rate triples.

Two different species of damselfish on top; dusky dottybacks on the bottom, cosplaying their way up the food chain

The dottyback’s serial, infanticidal deception has been described as a strategy akin to what is employed by the specious lupine in the “wolf in sheep’s clothing” fable. However, given the plastic, color-changing element at play here, the dottyback is more like a wolf in sheep’s clothing that incrementally eats all the lambs in one flock….then takes off its sheep disguise, trading it for “cow’s clothing”….then sneaks into the next field over to switch to eating veal for a while….and so on…each new field with more and more missing babies…

It’s possible that the zeal of the dusky dottyback’s attacks on Pomacentrus pipsqueaks makes ditching the ruse and starting over in a new area dominated by another species of damselfish completely necessary. The dottybacks may be sly, but not all of their strikes are a success, and many juvenile damselfish escape. Considering that dottybacks attempt to nab their nubile prey really damned frequently, there’s a steep learning curve among survivors as to figuring out which grown-up in town is the one to stay the hell away from. It may be that after a certain point, every remaining young damselfish in the bunch has narrowly escaped death enough times that the effectiveness of the dottyback’s disguise goes to shit, and the devious bastard has to shamble out of the community and set up shop in an area nearby that is ignorant of its reprobate plans, like some kind of stereotypically shifty drifter or something.

Life can be shitty, and full of shitty people, but remember that in the ocean, the resident assholes take things to a level you’re (hopefully) never going to experience. Be glad that even though you may have paid far more for that TV you picked up at Best Buy (despite what the sales representative convinced you of) than it was worth, at least he didn’t go false cleanerfish on your ass and bite your arm and steal your wallet as well. Also, be content in knowing that even if your parents are being passive aggressive and manipulative, you’ll never have to worry about your mom actually being some ravenous psychopath in a mom skin-suit who tries to cannibalize you in the kitchen when you visit for Thanksgiving….dottyback style.

This post series will continue: Part 6 will focus on fish that disappear into their surroundings as completely as Gene Hackman did from the entire world…

Image credits: Intro image (blue hamlet), 2nd blue hamlet, blue chromis, cleaner wrasses servicing a rockmover wrasse, bluestreak cleaner wrasse, false cleanerfish, dusky dottyback (brown morph) (Paddy Ryan), Saturn (Kronos) Devouring his Son by Peter Paul Reubens, dottyback/damselfish set (clockwise from top left: Ambon damselfish, lemon damselfish, brown dottyback (John E. Randall), yellow dottyback (John E. Randall))

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Mesmerizing Marine Mimics: Decoys of the Deep

This post is the fourth in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be. The first entry in this series goes over some fundamental introductory concepts and definitions regarding mimicry in general.

Up until this point in this post sequence on mimicry in ocean ecosystems, there has been a focus on examples of animals that have evolved to strongly resemble another species, entirely and completely, in regards to appearance and behavior. But not every mimic goes for copying the whole shebang. Sometimes, just mimicking a specific body part of another creature is all you need to get the job done. Or maybe a tiny portion of your own body is sufficient to parrot the entire visage of a smaller species. I like to call this particular flavor of deception “fractional mimicry”, because instead of whole organisms mimicking other whole organisms, it is organisms mimicking other organisms that are in radically different size classes, necessitating evolutionarily ingenious use of specific regions of the body, or the resemblance of such regions. Fractional mimicry works through the broad manipulation of shape and color, and more importantly, the perception of shape and color in other organisms. I’ve already talked about a species that uses fractional mimicry earlier in this post series; the mimic octopus, which can use a subset of its tentacles to mimic a sea snake, or poke just its stalked peepers out of the sand to mimic a partially buried mantis shrimp. In the same blog post, I talk about a jawfish that is likely mimicking the tip of one of the tentacles of the mimic octopus, following the octopus closely as it moves across the ocean floor: this situation is an example of “fractional mimicry” as I’ve defined it, as the whole body of the fish is used to imitate a small portion of the entire octopus.

There isn’t any significant difference, from an evolutionary or general biological standpoint, between “fractional mimicry” and any other form of mimicry. To be honest, I just needed a good way to break up all of these posts. Grouping together species that share “fractional mimicry” or share the distinction of being fish mimicking invertebrates, or whatever, just makes my life easier. Sorry if that’s a bit of a disappointment.

So, let’s get to talking about “fractional mimics”; animals that achieve all the deception, but with half the work.

This fetching little fish is the comet (Calloplesiops altivelis), although due to its showy, expansive fins, it is also referred to as the “marine betta” (especially in the aquarium trade). It is found on tropical coral reefs across much of the Indo-Pacific, and shares its genus with one other less widely-known species. The comet is a type of longfin (family Plesiopidae), a group of small, predatory, vaguely grouper-like fish somewhat closely related to damselfishes (in regards to damselfish, think clownfish, like Nemo from Finding Nemo). They are also thought to be cleverly subtle mimics. ‘Of what?’, you may ask. A sensible, spotted handkerchief? A floating cutout of a Lite-Brite?

In reality, the likely model for the comet’s mimicry is a living critter, with a lot more in the way of bones, and eyes, and skin. And teeth. Lots and lots of teeth.

Those are some eely nice spots you got there! *nervous underwater laughter*

That distinguished, maculated fellow up there with the thousand-yard stare is a moray eel, in particular, a turkey moray (Gymnothorax meleagris). This species is found all over the tropical Indo-Pacific, and has a range that overlaps significantly with the comet. If you are going back and forth between photos and squinting at each, not entirely convinced that the comet, with all its disjointed, dangly fins, looks anything like a turkey moray outside of the spots, consider that the comet can throw out some remarkable acting chops in a pinch. When startled, the comet has a habit of straightening its larger fins, placing all of their edges together to eliminate gaps, and gives itself a diamond shape. It also takes its pelvic fins (the thin ones that hang below from the front) and tucks them at its sides, enhancing its new arrow shape. The comet then pokes its noggin into a hole in the reef, leaving its tail end out and exposed, conspicuous “eye” spot in full view. When it does this, the comet looks less like Chicken of the Sea and more like something much, much less appetizing.

I haven’t seen a 180-degree turn around this effective since Robert Downey Jr.’s post-rehab acting career.

It is thought that this unique behavior, combined with the comet’s bizarre shape and coloration, is indicative of mimicry of the head of a turkey moray, which wouldn’t be much of a stretch considering how often morays sit motionless in their holes, their heads poking out so they can keep an eye out on the rest of the reef like a bored, nosy, suburban neighbor. I’m calling this “fractional mimicry” because the comet would only be mimicking the commonly exposed head of the moray, not bothering with the rest of the body. This would also be an example of Batesian mimicry, where an organism passes itself off as a more dangerous or distasteful species.

And morays are most definitely an appropriately dangerous model for a mimic to emulate. Moray eels have an unsavory reputation among many divers as extremely aggressive death-noodles crafted directly from the barbarity and hatred of Poseidon himself, full of scorn towards the folly of Man. While tales of their unbridled rage towards all human parts soft and defenseless are a bit overblown, moray eels will bite when provoked or frightened…which usually happens when divers or snorkelers unwisely stick their hands and arms down what they think are empty holes and crevices in the reef. Morays are typically content to stay the fuck away from big, intimidating oddities like ourselves…granted we reciprocate respect of their bubble of personal space. With moray eels, encounters of the “tactile” kind are a recipe for trouble for humans and marine life alike…which is why the popularity of misleading videos like this that show anomalously tame morays acting like eager puppies begging for food and scritches concerns me; “playing” with almost all morays in the real world will invariably end in bloody disaster.

That “bloody disaster” comes directly from the moray eel’s fang-studded bite, the ferocity of which is, unlike their nasty demeanor, not at all exaggerated. While some species have flat, strong chompers that have evolved to crush hard-shelled prey like crustaceans and mollusks, many are ambush predators of fish, rocketing out of hiding spots in the reef and nabbing prey on the fly like that giant penis space slug in The Empire Strikes Back. Fish are particularly hard to hold onto if you don’t have hands, so these morays have mouths filled to the brim with long, sharp, recurved fangs that do a damned good job of holding their wriggling dinner in place. These teeth are also great at doing a shitload of damage to anything that isn’t food…like a human hand. Yanking the deeply embedded eatin’-end of moray eel off yourself causes those fish hooks to run through your flesh like a tractor ploughing furrows in a field. The end result is lots and lots of stitches, if you’re lucky. Google Image search “moray bite” if you have the stomach for photos of hands reduced to nothing but tattered, scarlet ribbons.
Moray eels have even more teeth on a pair of second fucking jaws that lurk further down their throat. These “pharyngeal jaws” are modified gill arches that shoot forward after a fish is snared with the upstream jaws and help drag the hapless victim down into Stomach Town. These marvelous evolutionary inventions only come into play during feeding time, not defensive measures, but any animal with a mouth within a mouth, like an honest-to-Christ Xenomorph, should still be kept at a safe distance.

These predators, with their bites-of-mass-destruction, command a great deal of fearful respect among coral reef animals big and small. Thus, it would make sense if the comet has evolved to mimic the most dangerous end of a turkey moray eel in times of panic.

However, it’s possible the comet may not necessarily be directly mimicking a specific variety of moray, or even morays at all. The position of the fake “eye” spot towards the rear of the body may confuse predators as to where the head of the comet actually is located. For reasons that should be obvious, a bite to the tail region is far easier to survive than a bite to the face, and there is precedence in organisms that appear to use a secondary “fake head” to deceive attackers (an example that comes to mind is Australia’s shingleback skink, a turd-shaped lizard with a tail shaped closely like its head).
The utility of the “second head” strategy may actually extend to the comet’s own predatory habits. Comets slowly stalk their prey, incrementally edging closer, often turning on their side, waiting until the prey item makes a critical avoidance error. Then, the comet lunges, mouth open, at extreme speed. The “eye” marking may be useful in tricking prey, letting the target think the harmful end of the comet is further away than it truthfully is, allowing for a much closer (and successful) approach/seizure.

When one part of an organism’s body is used to mimic another part of the same body, as would be the case in the comet and its “second head”, this is called “automimicry”….loosely, mimicry of one’s self. Many times, this is used to deflect the advances of predators, either by confusing the hell out of them on where they should even attack, or straight-up scaring the everloving fuck out of them. On land, there are plenty of examples of automimicry. Northern pygmy owls (Glaucidium gnoma) have eyespots on the back of their head that give predators the impression that they are being stared down with all the silent malice of a disapproving mother-in-law. Automeris moths have huge, menacing “eye” patterns on their wings that can flashed at predators, making the moth appear to be a much bigger, much more dangerous animal than it actually is, potentially giving the predator pause, and opening up a chance for the moth to escape. Other examples abound, in particular among the more vulnerable groups of winged insects.

An example of automimicry in the ocean comes from the appropriately-named four-eyed butterflyfish (Chaetodon capistratus), a name that is markedly descriptive, yet sounds like a school-ground insult of generations past.

“*snort* Nice glasses, dweeb.”

The four-eyed butterflyfish, native to the warm waters of the Caribbean and West Atlantic, isn’t, of course, actually bespectacled, or the proud owner of a second set of eyes. On either side of the base of its tail is a large, black, white-ringed blotch that resembles one half of a pair of eyes. When alarmed, the butterflyfish promptly turns its ass towards whatever spooked it, and gets the fuck out of Dodge in the opposite direction. It’s thought that these “eyes” mess with a would-be predator’s head, seeing as how many predators aim for the eyes and head when making a kill. It’s possible this would allow the four-eyed butterflyfish to outmaneuver its pursuer in an underwater chase, since the predator wouldn’t be totally sure which direction the butterflyfish would dart, disrupting all ability to predict where to aim and lunge forward.

It’s one thing to use your Mystique-ian powers of shape-shifting, visual deception to lull prey into a sense of false security, or to scare off attackers with an intimidating facade ala those plastic owl decoys used to strike dread in the hearts of obnoxiously-loud, frequently-shitting songbirds….but it’s another thing to use mimicry to get your food to deliver itself straight to your mouth…..


Dusk is settling on the reef, and you, a small reef fish, are beginning to stir. Your nocturnal habits have demanded you stay huddled with your school under a coral overhang for much of the day, but as night approaches, you flit about, anxious to venture out into the dark and feed. The blackness grows still, and it feels like a warm and familiar friend. Before long, you’ve decided you’ve waited enough, and you cautiously dart out into the open, your senses trained on your surroundings for any sign of food. You rise up in the water to scan a coral head for food.
Suddenly, you spot something with your huge, saucer eyes, your vision keen in the low light. Movement. You stop, waiting for the motion to once again reveal itself. Again, not far from you, perched high up on a rounded lobe of coral, a sign of movement, confirmed by your sensitive lateral line system, which detects minute vibrations moving through the water. You carefully approach. It wriggles side to side once more. It’s a fish! Your tiny, sesame seed-sized heart quickens its pace in excitement. Your unblinking gaze locks on the fish as it wriggles again. It doesn’t seem to notice you, rhythmically worming in place, nearly resting atop the coral head.
You slowly drift closer. It’s just small enough to fit in your mouth (which, notably, takes up about a quarter of your entire body)…which means its small enough to be a meal. If you’d had salivary glands, your mouth would be watering right now. You get even closer, close enough to pick out its red and yellow colors in the dark. It still doesn’t see you! Your heart races in anticipation. This is going to be too easy! You slowly angle your head towards its beady black eyes. You inch forward ever so carefully, readying yourself to strike. Your mouth is damn near touching its face. In your tiny fish brain, time slows, and you begin counting down your attack. Three. The muscles in your jaw flex. Two. Your gills beat one last time. One.
Then, out of nowhere, the fish’s writhing body goes as rigid as a balance beam. Before you can process what you’ve seen, you feel a terrible rush around you, and blinding pressure and pain on either side of your body. You panic, beating your muscular tail with everything your body has, but you stay in place, your head enveloped in suffocating membranes, and your flanks clamped in place with a vice-like grip. For several seconds you thrash wildly, and as soon as you stop, you feel whatever has captured you flex, and you get sucked deeper. It’s darker than you’ve ever experienced in here. You can’t breathe, and soon, you fade into your gastric tomb.


Were you a more intellectually-gifted animal, your last moments would have been full of realization that it was no delectable fish that you had pursued, and that you had been deceived into your death. You had the misfortune of having met your life’s end in the hungry, patient maw of the decoy scorpionfish (Iracundus signifer), lured in by the promise of sustenance.

By and large, the decoy scorpionfish is pretty normal by scorpionfish standards. Scorpionfish (family Scorpaenidae) are a very large and diverse group of fish, mostly made up of ambush predators that lie in wait for prey on the ocean or reef bottom. Most scorpionfish spend most of their lives not moving, attempting to blend in with their surroundings. Smaller fish or crustaceans that stray too close are sucked into their huge mouths through the vacuum caused when scorpionfish open their mouth faster than you or I can even see. Many species of scorpionfish also have potently venomous spines on their dorsal, pelvic, and anal fins, which are, as you can imagine, incredibly useful defensive weapons. A famous, and slightly more ambulatory representative of this group is the beautiful, highly-venomous, and notably invasive lionfish (Pterois). A closely-related family, the stonefishes and ghoulfishes (Synanceiidae), as a group, are the most venomous fish in the world, with some species with stings implicated in human deaths. Like its relatives, the decoy scorpionfish, found on reefs all over the Indo-Pacific, is a bottom-dwelling, stagnant, patient predator, adorned with venomous prickles along its back, a set of lightning-fast jaws, and a face only a mother could love.

Pictured: The deadliest strawberry-and-creme dessert on the reef

What makes the decoy scorpionfish unique among its brethren is that weird band of yellow stretching across the webbing on its dorsal fin. While it looks like a traffic safety reflector, or like someone recently assaulted the fish with a highlighter, its purpose is far more devious.

That little orange and yellow streak is a lure for attracting small, predatory fish to right above that big ol’ ravenous Dyson of a mouth. Lots of other fish use lures to convince prey to come closer. A good example are frogfish and anglerfish (order Lophiiformes), which use vaguely wormy bits of flesh that they jiggle frantically like we would a piece of yarn in front of a cat. However, the decoy scorpionfish’s lure is way, way more sophisticated than the glorified skin tag nightcrawlers used by anglerfish. What do I mean? Well, take a closer look at that front dorsal fin; the part that sticks up like the mast and sail of a ship.

Photo: John E. Randall

How about now? No? That’s fine, I have a video:

Yeah. That lure, with its little “eyes” and “mouth” looks exactly like a small fish. The spine sticking up in the middle even looks like a goddamn dorsal fin! This is no half-assed bit of glowy, spaghetti jigger bait that just keys in on and exploits the stimulus response of prey fish. This lure looks like it was handpainted in an artisanal studio, and is equipped with markings that imitate the body and head of a fish in side view with mindblowing accuracy. The ruse is made all the more powerful by how the decoy scorpionfish broadcasts the presence of the lure. When luring prey, the black “eye” expands slightly in size, and the scorpionfish makes the “fish” “swim” by snapping the first two dorsal spines side to side. This makes the membrane-bound spines further back do “the Wave”, which mimics the wriggling tail and body movements of a fish. This is more than sufficient to garner the curiosity of hungry passersby. All they have to do is get a little too close….and then….WHAM! Sucked down the gullet in one or two gulps. Curtains. Grim Reaper. A locker belonging to a Mr. Davy Jones. You get the idea.

The decoy scorpionfish uses a form of “fractional mimicry” in the reverse sense of the comet, where a small portion of its body resembles the whole body of another animal, rather than the other way around. This is also a case of “aggressive mimicry”, which is sort of the inverse, in a way, from Batesian mimicry; the mimic looks either falsely harmless or enticing, rather than falsely dangerous or off-putting, assisting predation or other types of interactions that benefit the liar at the expense of the sucker. An example of aggressive mimicry that is incredibly similar to the tactics used by the decoy scorpionfish comes from Lampsilis mussels, which use an exceptionally convincing fish-shaped lure to draw larger, predatory bass in close, facilitating parasitism of their clueless target.

This post series will continue: Part 5 will focus on fish that use mimicry to engage in some of the most manipulative, sociopathic behavior under the ocean….

Image credits: Intro image of butterflyfish, comet, turkey moray, comet in defensive position, four-eyed butterflyfish, decoy scorpionfish #1

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.


Mesmerizing Marine Mimics: Sea Slug Style

This post is the third in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be. The first entry in this series goes over some fundamental introductory concepts and definitions regarding mimicry in general.

The previous entry in this series tackled fish that masqueraded as their flippity-floppity boneless distant cousins, generally to keep themselves from getting devoured by one of the endless multitudes of hungry mouths that tirelessly dart back and forth underneath the waves. The entry before that looked at fish that mimic other fish as part of the same evolutionary strategy. It’s worth mentioning that while I really like fish (I study the things, for Christ’s sake), not every bit of mimicry in the ocean involves gills and fins. Plenty of invertebrates (the perhaps less-than-charismatic things like worms and mollusks) in the oceans also engage in mimicry of other species. Sometimes, just like in the last entry, these imitations can jump across to completely different phyla (a major organizational grouping of life right below “kingdom” (like the animal kingdom, Animalia) and above “class” (like Mammalia, which includes mammals within the phylum Chordata)). It’s also important to consider that the phylum to which all vertebrates belong, Chordata, is just one grouping compared to a shitload of so-called “invertebrate” phyla…like thirty of them (the exact number depends on who you talk to…there’s plenty of taxonomic/phylogenetic disagreement to go around). Familiar, cute vertebrate critters like pandas and cats and goldfish and parakeets get a lot of attention, but in reality they make up a tiny sliver of animal diversity. The vast majority of the animal species on planet Earth are “invertebrates”…a commonly thrown out figure is something like 97% of all animals. In light of this, focusing specifically on some gooshy guys for one entry in this series seems only fair. I guess you say I’m…throwing them a bone….or something.

One group of invertebrates that is deserving of focus in the context of marine mimicry are the nudibranchs (pronounced “noo-dee braynks”). Their name means “naked gill”, which refers to their unique respiratory system. While they are regularly referred to as “sea slugs”, nudibranchs represent just one large taxonomic group of marine-living “slug” (the other groups include things like the solar-powered sacoglossans, a member of which is the “sea sheep” that everyone was losing their shit about a month or two ago, or the huge, ink-squirting sea hare, which is part of lineage distinct from nudibranchs). To reduce confusion on what variety of sea slug one is talking about, many folks refer to them by the shorthand “nudis” (pronounced like one would for “nudies”…although taking care to distinguish between things like “nudi photographs” and “nudie photographs” in casual conversation is STRONGLY RECOMMENDED).

Nudibranchs are nested within the Phylum Mollusca, which contains notoriously slimy, muscular, and often tasty animals like squid, octopus, clams, and mussels, along with snails and slugs. They are also “gastropods”, which are a class of mollusks commonly equipped with a muscle-bound sliding “foot”, and include everything from abalone to your typical garden snail. Nudibranchs make up a modestly-sized branch of the gastropod family tree (which is MASSIVE, with at least 60,000 species), but their 2,000 or so species are found in essentially every marine habitat, from shallow reefs to the deep-sea. They are called “slugs” due to their lack of a shell, but the land-lubber “slugs” that keep terrorizing your lettuce plants under the cover of night are far more closely related to terrestrial snails than they are to the maritime mollusks at hand; nudibranchs are not particularly closely related to either domestic variety of gastropod. The majority of species are remarkably delicate and tiny, growing only to about the size of a fingernail, but some are burly even by gastropod standards, like the Spanish dancer nudibranch (Hexabranchus), named for its gorgeous red colors and elegant swimming style reminiscent of a flamenco dancer, which can occasionally reach the size of a watermelon. The one pictured below, found here on O`ahu a couple of years ago, is significantly smaller.

Photo: Jake Buehler

Nudibranchs are renowned for their bizarre, alien appearances and explode-in-your-face colors. Honestly, these things are like extraterrestrials ala Avatar meets three hours into a balls-to-the-wall mushroom trip. There are blue dragon nudibranchs, which look like pipe cleaners designed by Dr. Seuss. There are variable neon nudibranchs, which appear to be fuzzy velvet posters that have come to life. Many are so intensely colorful they look man-made. The Hopkin’s rose nudibranch is pretty much identical to those unnerving, pink, moving, Koosh ball things in Jim Henson’s 1982 film The Dark Crystal:

But let’s be honest, everything in that movie is unnerving. Remember the landstriders? *shiver*

The white-lined dirona looks like the ghost of a feather boa, and the highly-venomous blue glaucus is the size of a nickel and glides through the open ocean like a six-winged dragon made out of periwinkle glitter. Some nudibranchs look remarkably like the tiniest, fluffiest bunny you’ve ever seen. The diversity of otherworldly forms and color schemes among the nudibranchs is impressive, and much of this has its roots in the evolutionary biology of these animals. Being soft, mushy, and slow is no way to go through life in the ocean…in particular because your life will invariably be cut short. An easy meal doesn’t stay unexploited for long. Many nudibranchs have managed to maintain their svelte, silky, shell-less figures and avoid extinction by finding other ways of defending themselves. Some take toxins they acquire in their diet (often from sponges) and concentrate it in their bodies, becoming distasteful or outright dangerously poisonous to would-be predators. It is then thought that the insanely, psychedelic colors are an advertisement of their toxicity, telling the ocean at large that they ain’t nothin’ to fuck with. Others that feed on cnidarians (things like jellies and anenomes) can store their food’s venomous stinging cells, putting them in fleshy extensions that cover their backs like a forest of blistering despair. Nudibranchs are like Rogue…if she had to cannibalize other mutants to absorb their superpowers through the lining of her stomach.

Because of this habit of sneakily taking “you are what you eat” to the next, noxious level, nudibranchs are known to be mimicked by other species that do not have the capacity to become nasty-tasting or embedded with the biochemical Angel of Death.

Consider, for example, the pimpled phyllidiella (Phyllidiella pustulosa), a small nudibranch native to the tropical waters of the Indo-Pacific. It is a commonly encountered nudibranch, and is notable for regularly venturing out into the open in the middle of the day, a brazen act for a defenseless little slug nugget. However, the pimpled phyllidiella protects itself with toxins that it steals from the sponges it slurps up as it slowly slides across the coral reef. Fish in particular steer clear of this nudibranch, possibly because of its inherent toxicity, but also potentially because it resembles a blood sausage infected with small pox.

Fish will literally eat each other’s shit, but Mr. Clearasil “Before” Photo over here is just too icky.

It’s a winning evolutionary move for the nudibranch, and one that has been exploited by a completely different kind of soft-bodied co-inhabitant of the reef. This go-getter? Pseudoceros imitatus, often referred to as just the “mimic flatworm.” As a flatworm, it is a member of the phylum Platyhelminthes, and as I’ve described in the previous entry in this post series, this means it is nowhere near nudibranchs in the animal phylogenetic tree, and is a member of a group characterized by having internal organ systems about as substantive and fleshed out as Presidential candidate Donald Trump’s foreign policy musings. Actually, come to think of it, Trump’s socio-political ideas have a lot in common with parasitic flatworm infections; both propagate via mouths that have stayed open when they really should have been shut….and through liberal expulsion of feces.

Make America Eat Again…and Again…..and Again….Stop Asking Me Why and Just Put Food in Your Face, Goddamnit, You Ain’t the Only One Who’s Gotta Eat Around Here

Anyways, the mimic flatworm, unlike many other varieties of closely related flatworm that DO produce defensive toxins (and are themselves models for various mimics), is benign. Fortunately, it has evolved to look strikingly similar to the co-distributed pimpled phyllidiella, and has the same pale purple patches of zit-like bumps interspersed with black striping.

The mimic flatworm has even modified its sensory antennae (on the left side of the image) so that they better resemble the rhinophores (the blade-shaped “ear”-like structures on the heads of nudibranchs that act like noses/tongues, sensing chemicals in the water) of the model nudibranch, rolling them into upright, black cones. One brief, passing glance at this flatworm slithering out in the open by a passing fish (who had previously had a sorrowful run-in with a toxic pimpled phyllidiela) and it’s unlikely the fish would be able to tell the difference, and would continue on its way….and the worm lives to see another day.

Other species from other invertebrate phyla hop on the Toxic Pretender Train as well. Take, for example, the blackspotted sea cucumber (Pearsonothuria graeffei). It, like all sea cucumbers, is an echinoderm, a member of the phylum Echinodermata. The echinoderm umbrella includes familiar ocean creatures sea stars, sea urchins, sand dollars, bristle stars, and of course, sea cukes. Echinoderms are actually very closely related to our own phylum, Chordata, and have a number of bizarre distinguishing features, like locomotion driven by a complex hydraulic system and five-part radial symmetry (meaning that they have a body plan equally divided around a central axis, and thus have no right and left “sides” like we do). Sea cucumbers make up the echinoderm class Holothuroidea, and are closely related to their urchin cousins, but tend to be more leathery and sausage-shaped than little, hard, spiny balls. Sea cucumbers like the blackspotted sea cucumber are scavengers, methodically shuffling through the sandy bottom of the ocean, pushing whatever rotting particles they can find into their mouth with their scoop-shaped oral tentacles and extruding the waste (and lots of sediment) out the other end. When disturbed, many sea cukes (including this species) will shoot sticky strands of their own viscera at their assailant from their own asshole, which, you know, is kind of off-putting. These specialized organs are very roughly analogous to gills or lungs.

Yes, you read that right, sea cucumbers, when scared, have their breath taken away…but only because they shit themselves hard enough to blast part of their respiratory system out of their ass. I’ve heard of some fearful sharts in my day, but I’m pretty sure that takes the cake.

The blackspotted sea cucumber is a fairly standard “holothurian”, butt stuff included. Lethargic. Dull in coloration. Looks a bit like a plastic bag wrapped around a blackberry bramble. Or a mosquito-bitten colon. Or kind of like the alien from John Carpenter’s The Thing was trying to morph into a gherkin, but got interrupted halfway through by Kurt Russell.

“Well, looks like we’re in a bit of a pickle, aren’t we?” *lights flamethrower*

The blackspotted sea cucumber is mainly a tropical Indian Ocean species, but can also be found into the Indo-Australian archipelago (Indonesia, Papua New Guinea, etc.) and the Philippines. They can grow to about a foot in length, and precious few animals would dare attempting to eat them at their full adult size…I mean…that’s potentially a lot of weaponized butt-guts to deal with. So what does this all have to do with mimicry? Well, the young of this species of sea cucumber look very different from the adults.

Take a gander at the baby blackspotted sea cucumber:

It’s the thing that looks like a piece of bird shit.

You see, when the blackspotted sea cucumber is just a wee little sea cukelet, it has white (sometimes bluish) blotches interspersed with black lines, and large, exaggerated thorny projections capped with orange or yellow….very different than the brownish, spotted adult form. Attracting attention to oneself through in-your-face colors isn’t a good idea if you a dinky foodstuff like the young sea cucumber above….unless you wish to get something else across to your co-denizens of the deep. It is perhaps no coincidence that this unique, childhood appearance is remarkably close to that of a variety of nudibranch (one that’s actually in the same taxonomic family as the pimpled phyllidiella above).

This nudibranch is Phyllidia varicosa. It is also known as the “scrambled egg nudibranch”, which is possibly the most viscerally descriptive name for an organism I’ve heard since I read about dog vomit slime mold. And it’s an accurate description…er…sort of.

Behold, the Great Easter Turd

The scrambled egg nudibranch is, unsurprisingly, poisonous and gross-tasting as hell, and fish keep this guy miles away from their mouths once they realize what those pretty pastel colors are dressing up. While the blackspotted sea cucumber is a youngster, it is an effective mimic of these toxic nudibranchs, possibly providing itself protection from fish predators. However, as it eats, and craps, and grows larger, it vastly exceeds the maximum size of its nudibranch model…and the effectiveness of the mimicry breaks down….which isn’t helped by the gradual color change to more muted tones. Luckily for the blackspotted sea cucumber, while the young are helpless in the face of predators, adults apparently become toxic themselves as they age, so all is well in mature, drab post-pubescent sea cucumber land.

This post series will continue: Part 4 will focus on fish that mimic body parts of other animals, use parts of their own bodies to mimic the whole bodies of other animals, or use parts of their own bodies to mimic other parts of their bodies….trust me it’s not as confusing as it all sounds….

Image credits: Introductory nudibranch image, pimpled phyllidiella, tapeworm and intestinal roundworm background image for Trump/Tapeworm 2016 composite, adult blackspotted sea cucumber, juvenile blackspotted sea cucumber, scrambled egg nudibranch

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Mesmerizing Marine Mimics: Fooling Across Phyla

This post is the second in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be. The first entry in this series goes over some fundamental introductory concepts and definitions regarding mimicry in general.

A fish that has evolved to mimic a completely different, potentially entirely unrelated species of fish is relatively impressive. It is a testament to the power of natural selection, this honing and whittling down of a creature so that it may converge on the same exact external form for the sake of protection or the easy procurement of food.

But fish all have the same overall “blueprint.” Paired fins, vertically oriented tail fin, eyes in the front, big, snappy mouth, gills behind the eyes, generally sleek and muscular…there are a number of distinctly “fishy” features that evolution doesn’t fuck around with too much. This sort of basic body plan of a taxonomic group is sometimes down as a “bauplan” and its sort of the generic physical shape and scaffolding with which a given lineage of organisms ends up modifying as different branches break off and try out different tweaks and strategies. The “bauplan” for a motor vehicle, for example, is basically four wheels with tires, a broad cabin for passengers resting atop the rolling chassis, windows, engine, headlights, perhaps a trunk in the back. Anyone can tell you that there are many differences between a Chevy Camaro, a Subaru Outback, and a Hummer, but all of them are superficial when you consider the motor vehicle bauplan they all share. Similarly, the alterations and adaptations associated with the evolution of mimicry in these fish are limited by the constraints generated by their overall body plans. A fish can only fake it so far, and imitating another animal with the same bauplan is completely within any developmental constraints.

But there are fish that manage to step outside the “vertebrate box” when it comes to pulling a fast one on their ocean community. There are some fish that are mimics of invertebrates; spineless, squishy, squirmy things that they haven’t shared a common ancestor with for well over 550 million years. These fish convincingly pass themselves off as things that aren’t even remotely built the same way, all through some clever innovation through the prism of evolution.

The stately gentleman above is a dusky batfish (Platax pinnatus), native to the tropical reefs of the West Pacific, ranging from Australia to the islands of far southern Japan. Batfish and spadefish (family Ephippidae) are beefy, disc-shaped, herbivorous fish found in the warm waters of the world. Most have very large, symmetrical, pointed dorsal and anal fins that, when extended, give them a distinctly triangular or arrow-shaped profile. Some species are of interest to sport fishermen, like the Atlantic spadefish (Chaetodipterus faber).

These imposing swimming silver dollars are bound to make an impression underwater, but if you ever came across a juvenile dusky batfish, you may not know it….because they, much like Jaleel White of Family Matters / Urkel fame, look absolutely nothing like their post-pubescent selves.

What the fuck is this? It doesn’t even look like a fish. It looks like a piece of one of Guy Fieri’s tacky bowling shirts came to life.

While this little guy’s high-contrast orange and black style may make him look like he was created by the Tron: Legacy design team, it is thought the odd appearance was crafted by evolution to serve a specific purpose.

You’ll note that Mr. Halloweenfish up there deviates from the adult form in more than just that vivid orange trim. Juvenile dusky batfish are shaped completely differently: they have long, elegant, flowing fins with jagged, broken edges, and a tiny head with small facial features that disappear into the sea of black scales. These fish are more thin, membranous fin material than actual meat, and appear like they’ve been carefully flattened with a rolling pin.

It turns out that baby dusky batfish share their ocean with another animal that looks remarkably similar, and it ain’t a damn fish.

Fig.1: Not a fish

At first glance, this may look like a fancy-shmancy, elegantly-riffled chocolate and orange-flavored cookie, but I can guarantee you wouldn’t want to put this thing in your mouth. In actuality, this is an orange-margined marine flatworm (Pseudobiceros periculosus), a native of tropical reefs throughout much of the Indo-Pacific. Flatworms make up the phylum Platyhelminthes, and are among the simplest bilaterally symmetrical (meaning they have two sides that mirror one another, opposed to multiple sides that mirror one another around a central point, like a sea star or a jelly) animals on the planet, lacking specialized organ systems commonly considered important by creatures like ourselves; respiratory and circulatory systems are completely absent, for example. The most familiar flatworms in the human world are parasites like tapeworms and flukes, but in the oceans, particularly on coral reefs, there are big, free-living species that swim and crawl all over the place. Many of them sport brilliant and beautiful colors, like the orange-margined flatworm above…typically to warn predators that they are toxic, taste like shit, or both.

So, mistakenly thinking P. periculosus is a delicious product of Pepperidge Farms would likely result in you aggressively spitting, scrubbing your tongue, dry heaving, and generally having an awful time.

It is thought that the young of the dusky batfish have evolved to look like poisonous and distasteful flatworms like P. periculosus (or P. periaurantias or P. affinis, other black species with bright orange margins). As full grown adults, these fish are powerful, fast swimmers, and rely on their athleticism and (in some species) habit of schooling in massive, closely-packed groups to evade becoming dinner for bigger, toothier fish. But young fish are small, solitary, and vulnerable, and trying to pass as a bitter, noxious item that predators stay clear of is certainly a workable survival strategy.

To enhance the quality of their flatworm impression, juvenile dusky batfish do more than just look the part. These fish do “the Worm”, but instead of drunkenly flopping all over the floor at your friend’s wedding reception, they take the dance a little more seriously, gracefully undulating their fins like a woman wearing a long, flowing dress. They move slowly while doing this, hovering just above the bottom in an attempt to mimic the beautiful, billowing swimming style of a marine flatworm. They will also swim on their sides to better match the “flat” shape of the worm.

This deceptive tactic is shared across the entire batfish genus (Platax), but the young haven’t all evolved to target the same model. The longfin batfish (Platax teira) have young that appear to mimic rotting leaves, as does the young of the orbicular batfish (Platax orbicularis). The juveniles of these species in particular hang out close to shore in brackish, sheltered mangrove thickets….which drop plenty of leaves into the water for them to blend in with. Platax batavianus, the humpbacked batfish, have young that show off stunning black and white stripes with long, fan-shaped fins, but as far as know, no one has offered a potential model for the mimicry likely exhibited in this batfish. Personally, I think the young fish, with its striping and conspicuous wing-like fins, looks like it could be mimicking a small lionfish….which are armed with a marvelously, debilitatingly painful venomous sting, and are therefore a more than worthy model to emulate to keep away hungry predators.

There are a number of other fish that have a big, strong, independent adult phase, proceeded by a childhood spent cowering next to the reef and trying to convince fleet after fleet of humongous submarines passing overhead, each propelled by a stomach that is never full, that they aren’t on the menu.

For example, there are fish of the genus Plectorhinchus. These fish, members of the “grunt” family (named for the sound they make when grinding their teeth together), grow to be longer than a man’s leg and are powerful, muscle-bound, predatory fish. Plectorhinchus fish root around in the sand and rubble to uncover and crunch down on invertebrate prey like crabs or worms, and are immensely aided in this effort by their giant, voluptuous, puckered, sensitive lips….which has led to their common name, “sweetlips.”

Looks like these charmers just heard about the Kylie Jenner Challenge.

But long before these guys are putting their DSLs to work near the top of the food chain, roving the seafloor in intimidating, ravenous gangs, they spend their awkward early years trying to be something they’re not.

One species, the harlequin sweetlips (Plectorhinchus chaetodonoides), found in the coral reefs of the Indian and west Pacific Oceans, makes a particularly dramatic transition between its elementary school form and its full-on tax-payin’, job-havin’ adult form. The leopard-spotted adults are shown in the photo above. The babies (below) look like a Holstein fucked a guppy and dressed up the resulting child like a flamenco dancer.

Pictured: a yearbook photo from the harlequin sweetlips’ totally embarrassing “nemo phase”

These little spotted buddies are solitary and stay near the shelter of the reef. It isn’t until they mature, trade in their polka dots for a classy suit of fine spots, and graduate out of their size bracket and lower rung in the reef food chain that they become the confident, shrimp-crunchin’ machines I told you about. But until then, much like the juvenile batfish, they keep alive by mimicking what is thought to be a poisonous flatworm or sea slug. I’m not aware of a specific model that’s been proposed for this species (or the other varieties of Plectorhinchus, which have similarly small, billowy young with coloration that looks very different than the adults’), and it may be that it looks vaguely “flatworm-ish” or “sea slug-ish” enough to do the trick.

What is apparent is that harlequin sweetlips juveniles have evolved a combination of visual cues, color patterns, and killer dance moves that are immediately called into action at the first sign of a potential predator. They make exaggerated swimming movements, flopping their entire body back and forth wildly, letting their broad, flaccid fins articulate with each dramatic folding of the fish’s body. This loosey-goosey undulating is something suspiciously similar to what something without a spinal column might do….something like a flatworm….or a sea slug (specifically, a brightly-colored nudibranch). They’ll also often point their noses down, and wriggle their fins and tail back and forth in a nearly stationary vertical position, further improving the ruse. Predators figure the twisting creature near the bottom of the reef is likely just a toxic blob of culinary disappointment and go about their errands, and the harlequin sweetlips lives through another day.

Poisonous flatworms are apparently one of the more successful choices for a mimic to model themselves after, because the list of wormy, pancake-like juvenile fishes is long. Another fish that appears to take the Platyhelminthes path is the white-blotched sole, Soleichthys maculosus, found in the tropical waters of the West Pacific and northern Australia. Soles, along with flounders, halibut, and plaice, make up the “flatfish” order of fishes, Pleuronectiformes. Like their common name suggests, flounders and their kin (in contrast to what depictions in certain Disney movies about mermaid minors with a hoarding problem might have you believe) are literally flattened, living their adult lives spread out across the seafloor, grotesquely compressed, like a submarine steamroller came on through while they were taking a nap. These pavement huggers typically use camouflage to blend into their sandy, pebbly surroundings, or burrow just under the most upper surface of the loose bottom substrate. But the white-blotched sole, especially in its youth, is an anti-conformist, and its black background is splotched with white, and its fins are bordered with bright orange. This coloration pattern is blatantly similar to that of a poisonous species of marine flatworm (and close relative of the proposed model for the dusky batfish juvenile) that shares its range with the sole, Pseudobiceros scintillatus.

Ugh. I got bleach spots all over my nice black washcloth.

While some flatfish are somewhat well-known for producing their own distasteful secretions (like the Red Sea moses sole (Pardachirus marmoratus), which excretes a milky fluid containing pardaxin, an effective, toxic predator repellent), the flamboyant white-blotched sole is very edible. Because of this, its mimicry must be convincing. Air tight. It’s not enough to look like a flatworm from a distance (being flat already gives you a leg up in that regard), you have to fall into the role head over heels and really sell the whole damn thing, soaring your method acting skills to Daniel Day Lewis-ian heights.

Young white-blotched soles completely alter the way they swim (much like the dusky batfish and the harlequin sweetlips), channeling their inner invertebrate, as can be observed in the video below from The Blenny Watcher:

When flatfish move across their two-dimensional environment, they kick off the bottom with a thrust of their tails and glide like a living frisbee to another spot to settle down, keeping close to the bottom like a hovercraft, moving swiftly with rapid strokes of the tail and back edges of their fins. But the white-blotched sole in the video doesn’t do that. No. This little guy cautiously and methodically scoots along the bottom like someone trying to covertly edge themselves closer and closer to the door so they can escape an awkward, under-attended house party without being noticed. Like I’ve said before, it’s hard to show definitively that mimicry is occurring, but when behavior matches up with appearance like this, it’s pretty convincing.

With all this talk of baby fish pretending to be flatworms, you’d be forgiven if you thought that was the extent of cross-phylum mimicry in the ocean. Adult fish are known to try their hand at this kind of deception, and with very different organisms. Flatworms are easy, if you think about it; decked out in radiant colors, and with a fairly basic body shape and no complex structures to imitate, they are also found commonly in the more productive reefs. Poisonous flatworms are an obvious “choice” for a model. But there are more creative options out there.

Consider the frogfish. This family of fishes (Antennariidae) is kin to the famous deep-sea anglerfishes and monkfishes (large, ugly critters regularly fished in the North Atlantic). Like the rest of the taxonomic order to which they belong, frogfishes are ambush predators, lying in wait either buried in sand or perched on a rock or coral head for a small fish to cluelessly stumble into the range of its lightning fast jaws. Frogfishes also typically use a wormy lure (called an “esca”) on their face that they jiggle seductively to entice a meal to come just a liiiiiittle bit closer. Most frogfish engage in a specific kind of mimicry known as “mimesis”, a type of camouflage that makes you look like your (typically living) surroundings. Different species of frogfish have evolved projections from their skin and patterning that makes them blend into their surroundings; from backgrounds like sponges, to seaweed, to coral, frogfishes are really fucking good at disappearing in plain sight. When you actually look at them, they are basically chubby wads of used chewing gum with fin “arms” and a face. Frogfish always look like someone just slapped an ice cream cone out of their hands and onto the ground.

“What the hell, man?! I was going to eat that!”

The disappointed three-time winner of the “World’s Fuzziest Peach Contest” pictured above is the striated frogfish (Antennarius striatus). It is an incredibly common species, and is widespread, ranging into every warm temperate to tropical marine body of water on Earth. Most of the time, they look like the individual above; like Carrot Top’s cousin that he keeps insisting lives “by” the ocean. But every so often, they look like this:

Gross. Look what Mittens hacked up again.

Occasionally, a completely black morph without any patterning shows up. These guys look like someone took a tangled hair plug from a shower drain and used it to decorate one of those black turds you get from drinking Pepto Bismol. This fish looks like it should be sultrily voiced by Tim Curry and plotting to destroy the Last Rainforest.

In the Philippines in 2005, these black morphs were observed congregating alongside a species of urchin. This urchin, Astropyge radiata, is nearly entirely covered in long, needle-sharp venomous spines that pack a burning sting…hence its common name, the “fire urchin.” As I’ve mentioned once before, getting stung by a venomous urchin is a less than pleasurable experience, and anything capable of inducing agonizing chemical rage like that is bound to be a good potential model for a mimicking species.
This case, where black frogfish are slowly shuffling alongside a herd of sea urchins, is, possibly, fairly unique in regards to sea-bound mimicry. If indeed the frogfish were associating with the urchins to better resemble one for its own protection (with the idea that larger predatory are unlikely to bite down on something that looks covered in toxic pokers), a “wolf in urchin’s clothing,” then this is sort of a new one for frogfish biology. This would be Batesian mimicry; when a species has evolved to look or behave similarly to another species that is harmful/dangerous/distasteful, garnering the mimic a level of protection. This is different than looking like a tuft of sea grass or a pile of rubble to avoid detection, because those are neutral objects…background elements. Batesian mimicry has the purpose of making the mimic look like it can cause more trouble than it actually can. It’s hard to tell if the frogfish are blending in with the urchins for their own protection, or for making their disguise towards prey more effective; as in, is this just good ol’ mimesis, since no tasty little fish would expect an urchin to be a threat? Urchins aren’t exactly known for lunging out of nowhere and snapping up fish faster than you can blink. It’s possible there’s three distinct forms of mimicry happening at the same time. 1) Batesian mimicry (frogfish looks like a venomous urchin, so nothing tries to fucking bite it), 2) mimesis (frogfish looks like slow, benign, herbivorous urchins, causing small prey fish to never suspect a thing), and 3) “aggressive mimicry” (frogfish uses lure to persuade dinner to mozie on over to its awaiting mouth hole). I’m not aware of any other creature on the planet that manages to be a lying, tricky, untrustworthy bastard in so many different categories.

You know, it’s funny, I always thought you were a fish….but now I know you’re a SNAKE.
Photo: Frank Schneidewind

If this is the case, there are some interesting evolutionary angles to consider, especially when you remember the black frogfish are just a single morph within a species. How often do these black frogfish and the urchins overlap with each other, and where? Does this opportunity for Batesian mimicry make the black morphs more “fit” than the other, more common, tan and yellow morphs?
Science noted this possible occurrence of mimicry for the first time only a decade ago, so there are still plenty of unanswered questions.

The striated frogfish may have dabbled in a diversity of mimicry methodologies, but there’s another animal in the ocean that has a repertoire of characters it can pull out whenever it needs to, and is a prodigal genius of targeted bullshittery; a masterful Kevin Spacey of underwater imitation.
I’m of course talking about the undisputed king of marine mimicry, the mimic octopus (Thaumoctopus mimicus). This small, wiry, normally white and deep brown striped cephalopod is found in open sand flats in the tropical West and Central Pacific, as well as around the Great Barrier Reef. Thaumoctopus is a bit of a dickish, overachieving curve-ruiner when it comes to mimicry, far and away surpassing the capabilities of any other animal in the ocean with at least a dozen different models it can mimic.

Here’s one mimicking a boastful smugfish (Phallocephalus elatus)

This Swiss Army knife of deceit can casually contort its body and long, trailing tentacles into whatever animal seems like the best option at the time. This is a video showing just a few tricks up its eight sleeves. Lionfish. Sea snakes. Mantis shrimp. Jellies. Crabs. Tube worms. Sea squirts. Sponges. Flounders. The list goes on. Thaumoctopus‘s CV is extensive enough to land it a spot on the cast of SNL…and to be honest, it might be a bit of an improvement.

“I haven’t seen this much ‘floundering’ since every skit that Kyle Mooney has ever been in. BA-ZING!”

The mimic octopus is impressive as shit, but, as I’m sure you, astute reader, have noticed….the mimic octopus is not a fish. I’m listing this mollusk here not to go over the minutia of its mind-blowing powers of duplicity, or to really talk about it much at all, as mimic octopus have been talked about plenty since their discovery in 1998. No, I’m still actually aiming to talk about a fish that mimics an invertebrate….an invertebrate that just happens to be the most adept and versatile mimic in the ocean.

To understand what I mean, you need to check out this video below from Luiz Rocha from the Cal Academy of Sciences, and featured here:

Behold, the antics of the black-marble jawfish (Stalix histrio), which appears to mimic the tentacles of an on-the-move Thaumoctopus, behaving like a ninth arm as it sticks close by. Jawfish, members of the somewhat recently-evolved family Opistognathidae, are vaguely blenny-like fish with big, blunt heads, large mouths, and narrow, tapered bodies. They are homebodies, and spend much of their time submerged in burrows defending their tiny territories. Because of this, jawfish aren’t all that great at the “swimming in the open” thing that most fish do. They are also quite itty-bitty, with no toxins, spines, or mace to protect themselves with.

Let’s be real here, the most disarming thing about the black-marble jawfish are those puppy dog eyes.
Photo: Dray van Beeck

It’s been offered by the scientists that first described this relationship that Stalix histrio has found a means to move out in the open safely and securely, by hitchhiking along yet another completely unrelated mimicking species in possibly the only known case of “mimic-ception” on Earth. Think about that. The mimic octopus is so powerfully talented mimic of sea life to grant its own protection, that a teeny species of fish has evolved to mimic it for its own safety. That’s how good at its job the mimic octopus is. I’m not entirely sure the jawfish isn’t hanging out with one of the mimicry greats on some kind of mimicry apprenticeship or something, and is seeking to learn the tricks of the trade from a mentor. The entire thing sort of feels like when there’s a fictional TV show existing entirely within the world of a fictional TV show. Nature shouldn’t be that meta. I’m not sure I can handle it.

This post series will continue: Part 3 will tackle mimicry among the spineless and slimy…

Image credits: Intro sweetlips photo, adult dusky batfish, juvenile dusky batfish, orange-margin flatworm, sweetlips adults, sweetlips juvenile, P. scintillatus, brown frogfish, black frogfish, mimic octopus, mimic octopus as flounder

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.

Mesmerizing Marine Mimics: Counterfeit Malicious Fish

This post is the first in a six post series outlining the evolution of mimicry within the ocean realm. These posts detail various ways in which organisms may copy other organisms in appearance and behavior, and the evolutionary context for how these mimic-model pairings have come to be.

In the human world, being a “poser” can have serious repercussions.

Well, at least if you are found out by those around you. No one appreciates a fake. A phony. A liar. A disingenuous, duplicitous slimeball. Someone who is, as a notably troglodytic hobbit habitually says, “false.” Someone who appears to portray themselves as something they are not tends to raise the hackles of anyone in their immediate social circle. Sometimes, the issue is a complete breakdown of trust, and an inability for anyone to take your word or feelings seriously. You become an actor. A poor one, one that nobody believes. Sometimes, the transparency of your guise just becomes annoying and exasperating. Like if you saw Little Dragon do a set “at Sasquatch one year” and that was the only time you ever saw them perform, before or since, but now all you do is talk to your friend about how much of a “huge fan” you’ve always been, even though I…I mean your friend…was listening to Machine Dreams back when you were still listening to Jason fucking Mraz like an uncultured jackoff….even though you didn’t know about their collab with Gorillaz, and when asked where they were based, you shat out something about “New York mostly I think.” IT’S GOTHENBURG, FOR FUCK’S SAKE. STOP ACTING LIKE YOU KNOW THINGS, JEFF, BECAUSE YOU DON’T.

….anyways, posers can rub people the wrong way.

But in much of the natural world, faking your way through life may be a great strategy to keep alive and produce lots of offspring. Any trait that gives you in edge in getting food, not becoming food, and making sure you can make lots of babies (which also can get food and not become food) is likely to proliferate in the population. Sometimes, this means using deceit, and looking and behaving like something you are not. When a species resembles another in behavior or appearance (or any other sense), this is known as “mimicry.” The organism that a mimic is imitating is referred to as a “model”, and importantly, mimicry only really works for the mimic if the model is found in the same area. Evolutionary biology is rife with examples, many of which are found in terrestrial ecosystems, and often involve insects…because, partially, there are likely millions of insect species on the planet from which instances of mimicry can evolve. There are swaths of moths that have evolved to resemble wasps, and the moths benefit by fooling predators into thinking they can deliver a painful, venomous sting. European bee orchids have flowers that look very much like the solitary bee Eucera, successfully attracting horny male bees, which then find themselves inadvertently dry-humping a cruel, floral-scented bee blow-up doll, all the while unknowingly satisfying the pollen transportation needs of the orchid. The chicks of the Amazonian cinereous mourner (Laniocera hypopyrra) appear to mimic a fuzzy, rust-colored variety of noxious caterpillar, which helps them not get harassed by hungry wildlife, but at the cost of looking like something that would scamper off the scalp of a particularly controversial 2016 Presidential candidate that shall not be named. These are just a fraction of the examples. In the history of life on Earth, mimicry has evolved over and over again, because, quite simply, it can really pay to pretend to be something you’re not.

Of course, since mimicry is a bit rampant on this planet, it’s perhaps not surprising that there are many examples in the ocean. By and large, marine organisms aren’t the go-to for examples of broad evolutionary and ecological patterns, mostly because they are less familiar and accessible than terrestrial lifeforms (seeing and interacting with marine organisms requires getting under the water or out on a boat, typically, which is far more difficult than just walking out into your backyard to see land-living counterparts). For this same reason, science is comparably in the dark about rather basic things about how ocean communities work that we’ve nailed down for terrestrial ecosystems long ago. Many details are missing, despite us being aware that the level of biodiversity in the ocean is likely nearly comparable to what exists on land. So, for this series of posts, I’m going to address some of what we do know about these tricky evolutionary dynamics that are going on in the relatively hard-to-access and hard-to-study briny deep. Frankly, insects have had their day in the sun…er….I guess somewhat literally in this case.

Look at the photo of the pair of fish at the top of this blog post. It may interest you to know that those two fish are not of the same species. Ok, you may nod at your computer screen, that’s possible. “Cryptic species” (species that are essentially morphologically identical to one or more very closely related species, but based on divergence at the genetic level, are wholly separate species) are a common thing in nature (probably more common than we give it credit for), and are certainly known in marine fish. But, this is not what is going on in this case. These fish are not close relatives, only differing in the slightest of genetic differences. They aren’t even kissing cousins, and in fact, they are on fairly different branches on the “tree of life.” These two fish are actually in entirely different taxonomic families. Within taxonomy, a “family” is a fairly large division, and organisms that are within the same order, but different families, can be separated by many tens of millions of years. One of these fish has evolved to look virtually indistinguishable from another species…a species that it hasn’t shared a common ancestor with in many millions of years….a quantity of time for its lineage to experiment, evolutionarily, with a multitude of different body shapes, swimming methods, dietary changes, etc. in parallel (but not together) with the lineage that eventually gives rise to its model. This is almost the equivalent of two classmates from high school meeting again at a 20-year reunion; at one point, their world experiences and who they were as human beings was relatively close, being peers, but the combination of time and divergence of experience has left them, at the endpoints of their respective journeys, wholly different, long since separated entities. The distance between the tines of the fork in the timeline of their lives is far greater at the tips than at the initial split. The mimic is far removed in evolutionary time from its model, and the inherently different path its ancestors have taken have left its mark on its biology…and yet it manages to be a maddeningly convincing copy.

How convincing? Well, I originally had planned on sharing a completely different photo that showcased both model and mimic side-by-side. In fact, I had it sitting in a photo folder for hours, and I had spent quite a bit of accumulated time looking at it, between scrolling up and down this page as I was writing this blog post once I had slapped it up at the very beginning of the entry, and seeing it in the folder itself. It took me an embarrassingly long time before I stopped and stared at this photo, squinted in disbelief, and conceded that I had made a mistake, and that the featured photo actually showed two of the same species of fish, and that…pathetically….not even the person writing a fucking blog post about these fish could reliably tell them apart.

Pictured: A pair of assholes that make me question my intelligence, eyesight, and sanity.

The composite photo above makes finding their differing features much easier (it’s basically one of those “spot five differences” puzzles), but this type of comparative scenario is about as ideal as it gets, especially compared to a grainy photo of entire school of these things, or in life/video, when these fish are flitting about.

The fish in the top photo is the model. It is a Valentinni’s toby (Canthigaster valentini), and is a variety of pufferfish (Tetraodontidae) also commonly referred to as a “sharpnose puffer.” This species is also called the “black saddled toby” or the “saddle puffer” in reference to the black bands on its back and sides. Tobies (genus Canthigaster) encompass nearly forty species, and are found in tropical and subtropical reef environments the world over (but with far more diversity in the Indian and Pacific Oceans). These fish are small by puffer standards, and often only reach a few inches in length.
On the bottom is the mimic that has evolved to resemble the saddle toby. It is the blacksaddle filefish (Paraluteres prionurus). Filefish make up the family Monacanthidae, and are found in warm ocean waters around the world. This species, unsurprisingly, has a distribution that mirrors that of its toby model, ranging from East Africa east through the tropical Indo-Pacific to Fiji, north up to southern Japan, and south to the Great Barrier Reef.

Pufferfish and filefish make up two families within the order Tetraodontiformes, which also includes other rather bizarre groups like boxfish, triggerfish, and the massive ocean sunfish. While this means that they are closely related within the grand scheme of fish evolution, these two families are separated by more than 60 million years of evolution, meaning that their most recent common ancestor may have been swimming in the oceans around the time the big, non-tweety bird categories of dinosaurs were snuffed out of existence. For some frame of reference, 60-65 million years is roughly how far you’d have to go back to find the most recent common ancestor of humans and aye-ayes. So yeah, these two lineages have had ample time to develop some very large physical differences from one another….yet the blacksaddle filefish does a fine job of passing itself off as a toby.

But why bother? Trying hard to look like something you’re not seems reserved for things like trying to be impressive on a first date, gliding past all your flaws for a job interview, and attempting to convince the pizza delivery guy that you really aren’t a sad, slovenly hermit who legit ordered an entire meat lover’s pie for yourself at 9 pm on a Friday. There must be a compelling evolutionary reason for this ruse.

And there is. Black saddled tobies are splendidly poisonous.

Tobies, like many members of the pufferfish clan (and the closely-related porcupinefish (Diodontidae)), embed their skin and organs with potent toxins, in particular saxitoxin and tetrodotoxin (TTX), the latter of which is a compound so aggressively neurotoxic that it has given puffers the fearsome reputation of being used to generate one of the most dangerous dishes in the world. These powerful poisons are an effective deterrent to becoming a much larger fish’s meal, and this, combined with the hallmark pufferfish capacity to inflate with seawater to several times their original size, makes black saddled tobies an unwise choice for a meal; if it doesn’t inflate in your throat and choke you, it’s bound to sicken or kill you following digestion. For this reason, most fish that share the waters with these tobies have either evolved to not see these fish as food, or have learned to avoid them through unsavory prior experiences. Black saddled tobies are an Untouchable caste on the reef, and this keeps them alive.

If you are small fish and you share an environment with a fish that predators won’t touch with a ten foot pole, being a copycat will end up having its benefits. This scenario, where a harmless species permanently cosplays as another harmful or distasteful species as a defense against a common predator, is a subtype of mimicry called “Batesian mimicry.” It is particularly well-known in insects, but it is also seen in this pair of fish; the filefish, without toxins of its own, exploits local predators’ aversion to small, white, diamond-shaped fish with black stripes and yellow tail fins by fitting this description to a tee. The filefish doesn’t actually need to be the coral reef equivalent of the ancient mystery Tupperware in the back of the office fridge that no one wants to eat, it just has to play the part. The blacksaddle filefish enhances this costume’s power even further by commonly shoaling alongside groups of its toby model. Some 5% of the fish making up aggregations of black saddled tobies are actually mimic filefish attempting to discreetly blend into the crowd.

As impressive as the mimicry is, there are still small ways to tell the two fish apart. The easiest way is to look at the dorsal and anal fins (the fins on the back and rear underside of the fish), which is actually a little surprising when you realize that both species have Saran wrap thin, transparent, hardly visible fins. In profile, you can see that the toby has narrow, oar-shaped fins, while the filefish has long, undulating fins that stretch a great deal down the back and along the underbelly. The ribbon-shaped fins of the mimic filefish are a component of its evolutionary legacy it hasn’t escaped in trying to imitate the black saddled toby. Another tell-tale sign that you are dealing with a filefish? A rigid dorsal spine, found in all filefish, that usually lays flat against the back to enhance the disguise, but when it is rarely erected, making the filefish look like a member of an undersea “Little Rascals”, it completely destroys the disguise like some kind of reverse version of Clark Kent’s glasses. There are some other minor hints as well, like how filefish generally have compressed, inflexible bodies shaped like an empty pita bread made out of leather, while tobies are a bit more like two Hershey Kisses fused together at their flat, wide ends. Of course, in profile view this diagnostic feature is nearly impossible to discern accurately. There’s also the presence of bluish stripes behind the eyes of adult male tobies, which are absent in their filefish mimics. If you think all these examples should make differentiation between the two fish easy as hell, give it a shot by watching the following video from The BlennyWatcher Blog; it’s not as easy as you’d think when the little bastards are all swimming around:

This model-mimic system is made more complicated when you realize there is potentially a second mimic trying to get in on the toxic toby action. Meet Plectropomus laevis, the blacksaddled coralgrouper, found throughout much of the tropical Indo-Pacific.

Weird. I feel like I’ve met you before…

The fish above is a juvenile, and is only a few inches long (conveniently within the size range of a toby). Adults can be nearly four feet long, and as they age, their markings deviate further away from looking like the black saddled toby (more yellow on the fins and face, thicker black stripes, etc.). But, when these fish are young, they look very similar to Canthigaster valentini. It is possible that they, much like the mimic filefish, are also exploiting the toxicity of the model toby, and the fact that predators don’t mess with things that look like these tobies.

It’s also possible that there’s an additional benefit provided by this mimicry. Blacksaddle coralgroupers are voracious carnivores, and spend their days stalking and snapping up smaller fish into their wide, extendable maws. Juveniles of the species are no exception. Tobies, on the other hand, aren’t exactly the terrors of the deep, despite their toxic defenses. Tobies have an unintimidating tiny mouth and beak (made out of fused teeth) used to prune tiny crustaceans and other invertebrates from the surface of rocks and coral, and are basically a derpy turkey baster bulb with eyes. Juvenile blacksaddle coralgroupers could also be using their decorative deception as a means of looking less dangerous than they actually are…like nothing more than a harmless, omnivorous toby…allowing them to approach prey fish (however, as far as I know, no one has documented this being an observable factor in feeding behavior for the coralgrouper). This “wolf in sheep’s clothing” variety of mimicry is called “aggressive mimicry”; it is imitation with the purpose of lulling a target into a false sense of safety, only to have that target learn that it is not at all safe in an abrupt and dramatic fashion. Aggressive mimics aren’t actually cognitively aware of their own deceptiveness. Rather, their mimicry is the result of selection for behaviors and appearances that positively impact fitness. Their craftiness is not driven by an actual conscious plan, because this would require the mimic to fundamentally be aware of the presence of the mind of its prey (and to be able to anticipate how it will respond to external events), and this is a capacity known to occur in only a precious few of the planet’s most intelligent species of animals…and, here’s a clue, one is reading this blog post right now.

I should also directly note why I have said that the juvenile blacksaddle coralgrouper is “potentially” mimicking the tobies. Mimicry is particularly difficult to “prove,” largely because it’s hard to disentangle two co-occurring species that look alike because one has evolved to look like the other, from two co-occurring species that look alike out of coincidence. Specific coloration patterns, for example, have evolved many times over the course of life on Earth, mostly because they can serve specific functions unrelated to mimicry. When two co-occurring species look alike and are closely related to one another, it’s also possible that their close evolutionary juxtaposition is more at play than anything else. In the case of the tobies and the filefish, the argument for the filefish’s conspicuous similarity to the toby being more than a coincidence is significantly bolstered by two things: 1) the modification of the general filefish body plan to look specifically more toby-like (when color AND form converge in the same direction, that’s a pretty good indicator that something very directional is at play), and 2) the fact that these filefish regularly school with the saddle tobies, enhancing the quality of the mimicry greatly. Usually a combination of traits, like coloration, body shape, movement, and behavior…all appearing to mimic those of another species…boosts any argument for a clear case of the evolution of mimicry.

Being a copycat runs in the family for these filefish, as the only other member of the genus (Paraluteres), its closest relative, is also a mimic of a species of toby.

The top photo is of the model, Canthigaster margaritata, also known as the pearl toby. It is endemic to the rich coral reefs of the Red Sea (meaning it is found there and nowhere else). Below it is Paraluteres arqat, also a Red Sea endemic species of filefish, which appears to be a mimic of the pearl toby.

These examples of Batesian mimicry are fairly simple. A single model with one (or maybe two) mimic species. However, there are instances where a single model species is surrounded by a cloud of mimics, all independently donning the ocean’s version of a leather jacket and shades to look far more badass than they are actually are.

Let’s play a game. Below is a grid of four fish photos; one of them shows a model species, and the rest are mimics. Can you tell which one is the real deal and which ones are posers? And no, the answer is not “that housekeeper lady, Alice.”

“….all of them had hair of gold, like their mother…”

This wasn’t a game you were supposed to win, because unless you are a fish nerd like me, you would have no way of answering that question. The fish in this image that all the others have, we think, evolved to emulate is the one in the upper left-hand corner.

What exactly is the name of this popular fish with all the die-hard fans copying his signature look? Say hello to Meiacanthus grammistes, the striped poison-fang blenny. They are found on sheltered coral reefs all across the Western Pacific, from Papua New Guinea/northern Australia and throughout the Indo-Malayan Archipelago, to the islands of western Micronesia and the Ryukyu chain near Japan. Blennies (fish of the suborder Blennioidei within the order Perciformes) in general are a varied group, ranging from gigantic kelp-forest forms, to diminutive forms that perch cautiously on coral heads, to things like the sarcastic fringehead, which has apparently decided that it’s Steven Tyler. Most blennies are a secretive and benign bunch, opting to park their elongated bodies on a rock or coral branch, or hide in a hole, trying to remain still to avoid detection by predators and patiently waiting for food to drift or walk by, often in the form of a small crustacean or fleck of plankton.

But the striped poison-fang blenny is not like most members of its family (the combtooth blennies, Blenniidae), and stays about as still and serene as an eight year-old stuck inside a library an hour after shotgunning one dozen Red Bulls. Meiacanthus blennies tend to be active swimmers, and dart around well above the reef bottom, doggedly protecting it’s turf from everything the general vicinity with all the confidence and righteous swagger of someone who just ran into their ex and saw just how unattractive they have become since the breakup. These torpedo-shaped, yipping “sea chihuahuas” may only grow to three inches long or less, so you’d think they’d be an easy little snack for a predator to snap up while passing through the neighborhood, especially considering how brightly colored so many species in this genus are (some of them look like they mush have shanked Jeff Bridges to flop out of the Grid and escape into the ocean, and others look a gas stove flame and brought it to life).

But they aren’t. In fact, predators won’t go anywhere near the angry little bolts of fishy lightning. It turns out those bright yellow markings and bold stripes on Meiacanthus grammistes aren’t just there to show how severely and fashionably punk rock these teeny hellions are, but primarily serve as a stern warning to the rest of the reef….a warning that says “I AM VENOMOUS AND I WILL BITE YOU. I WILL BITE ALL OF YOU.”

“I came here to chew bubblegum and bite faces…and I’m all done chewing bubblegum.”
Photo by Martin Klein of Bluevisions

Yes, blennies in the genus Meiacanthus are collectively, and colorfully known as “poison-fang blennies” for the very real fact that they have a pair of enlarged, sharp canine-like teeth in their lower jaw that has a groove on its front side that is connected to a venom gland embedded in the jaw below. These fish, as far as I know, are the only fish in the world to have evolved a venomous bite; venomous stings, in contrast, have evolved in many groups of fish (scorpionfish, stingrays, rabbitfish, weevers, and stargazers just to name a few).

The biting action compresses the venom gland, sending venom up the groove in the curved fangs, and straight into the flesh of whatever decided it wanted to have a bad day that day. Poison-fang blennies only appear to bite other animals in its environment as a means of self-defense, or in defending its territory, not for acquiring prey. Poison-fang blennies are partial to plankton, mostly. While the venom doesn’t appear to be very effective on humans (outside of the pain of being stabbed with a pair of tiny, blood-drawing daggers when getting a bit too close when attempting to clean the aquarium), possibly due to huge difference in size (envenomation may be made difficult due to the small size of the fangs, comparatively, and the sheer size of a human body might dilute the effect of the dosage injected) it apparently does the trick against just about everything around it in its natural habitat…because nothing dares to touch it. On the reef, the poison-fang blenny definitely has a bad reputation, and much the same vein as Joan Jett, this fish really doesn’t give a damn about it.

This nasty reputation is ripe for exploitation by mimics, and this is why there are at least three different species, all from distinct evolutionary lineages, all converging on the same strategy of acting like the friendly neighborhood MMA fighter with terrifyingly unresolved anger issues. From an evolutionary standpoint of these mimics, the striped poison-fang blenny isn’t a belligerent, piscean d-bag with a butterfly knife, but a go-getter worthy of shamelessly plagiarizing, an idol of sorts, the Most Interesting Fish in the World….

The mimics are, counterclockwise from the upper left corner, Petroscirtes breviceps (a non-venomous species of fangblenny in the same family as Meiacanthus), a juvenile Scolopsis bilineatus (the two-lined monocle bream), and Cheiliodipterus nigrotaeniatus (a species of cardinalfish). The fangblenny is a close relative of Meiacanthus, but the monocle bream and the cardinalfish are both in different, distantly related families.

But it doesn’t just stop with this particular species of Meiacanthus, several other species of poison-fang blenny have “inspired” a cluster of satellite mimics…many of them also different species of monocle bream, fangblenny, and cardinalfish. Hell, the juveniles of Scolopsis bilineatus look differently in different parts of their geographic range, having evolved to mimic whatever resident species of poison-fang blenny has set up shop on the reef. Say what you want about the monocle bream potentially taking their inherent lack of originality overboard, but that’s some “loconomics”, community-minded, sustainably harvested shit right there.

This post series will continue: Part 2 will delve into the select few fish who not only pull off looking nothing like themselves, but nothing like any fish in the sea….

Image credits: intro image of toby-filefish pair, toby-filefish comparison: toby / filefish, Plectropomus laevis, Red Sea toby-filefish comparison: toby / filefish, grid image: mimic fangblenny / Meiacanthus grammistes / mimic monocle bream / mimic cardinalfish, Most Interesting Fish in the World modified from this photo by Klaus Steifel

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.


Claws: The Ultra-Jumbo Class of Crustaceans

Last month, the U.S. media engaged in a bit of a kerfuffle over a particularly beefy lobster that had been pulled out of the ocean at the Bay of Fundy. At some 23 pounds and an estimated near-century of life on this planet, the king-size crustacean is a worthy subject of a perennial news cycle that manages to somehow focus on monstrously outsized shellfish. The Fundy lobster isn’t alone, and is one in a line of many other big buggy bastards from all over the world that have received attention by tipping the scales at 20 or 30 pounds or more. The reasons why knowledge of humongous lobsters eventually ends up being mass shared are because 1) it happens to be a slow news day, 2) photos with people alongside lobsters posed in forced perspective to make them look even larger are awesome, and 3) it’s damned impressive, considering the average lobster that makes it to Red Lobster’s Spectator Tanks of Inevitable Death is only two or three pounds, a fraction of the size of these animals.

This is great and all, but our planet is populated with entire species of crustaceans that reach strikingly, unexpectedly insane proportions as a part of their normal biology. Perhaps the most famous, and most recognizable of these is the Japanese spider crab (Macrocheira kaempferi), an unsettling, spindly, deep-sea demon that looks like the end result of the Slender Man impregnating a shrimp, and at their largest, can outweigh your samoyed and bear hug a Ford Focus.

“AHHH, what the hell! Sorry, sorry, sorry…I’ll make sure to knock next time!”

But there are other crustaceans slowly shambling about under the waves, along sandy beaches, or even in familiar rivers and streams that are strikingly massive, and get comparatively little attention, despite being some of the biggest, crustiest, clicky-clacky pinch-mongers around.

One of these is the Tasmanian giant crab (Pseudocarcinus gigas), a species that, as its name indicates, is found in the cool waters over the continental shelf of Southern Australia and into the waters surrounding the northern coast of the island of Tasmania (in particular, the Bass Strait, the ribbon of ocean that runs between the island and mainland Australia). As far as overall appearances go, the Tasmanian giant crab isn’t bizarrely constructed like its distant cousin, the Japanese spider crab. It looks very….well…crabby. Broad, oval, shield-shaped carapace splashed with red with creamy white underneath, a pair of clawed arms, a bunch of short, bendy legs, stubby, twitchy mouthparts and feelers…..pretty standard as far as crab features are concerned. Pretty standard for its closest relatives as well; Pseudocarcinus gigas is the only member of its genus on Earth, but other members of its family (Menippidae) abound, and are often referred to as “stone crabs” for their stumpy, rounded, boulder-like body shape (one of them, the Florida stone crab (Menippe mercenaria), is popular as human chow in some regions of the southern U.S. and Caribbean).

The thing that makes ol’ P. gigas stand out from the crustacean crowd is what’s inferred by its species name, “gigas“, which literally means “giant.” Pseudocarcinus gigas gets big. It gets really, scary big. How big is “scary big”? Let’s just say that if the Krusty Krab was owned by this brachyuran behemoth, Spongebob would be continually shitting into every literal corner of his pants.

“Keep those patties comin’, boy, or I’ll cut ye asshole to gullet! Yek yek yek yek!”

The biggest Tasmanian giant crabs can weigh as much as 30 pounds, and have carapaces broader than the wheels of many cars, which is more than a little fucking horrifying. I become sweaty and uncomfortable when something very similar to the thing I crack open and delicately serve with mayo, citrus, and greens looks like it could clip off my arm and beat me with it. Seafood has no business being that big. I mean, these Tasmanian titans can grow as heavy as a human 2 year-old….and when picked up, nearly as ornery as one.

“Auuuugh! Who do you work for?! Is it Silver? Captain D? Joe? Tell Joe I’ll splinter his femur AND his goddamned, precious Shack!”

By far the most bladder-emptyingly intimidating trait of Tasmanian giant crabs are their asymmetric claws, one small and one large, something they share with many other members of their stone crab family. One of their claws is a wicked, armored machine of mythic proportions, a bony cage harboring more rippling muscle than what graced the forearms of a heyday Arnold Schwartzenegger, capable of shattering snail shells and human hands alike….and then there’s the “big” claw. The “big”, right-hand claw is a ridiculous, Mephistophelean apparatus, massive to the point of being grotesque, like some kind of unholy, supernatural mutation. Like the crab got caught stealing clams from Ursula the Sea Witch’s garden or whatever, and she cursed him with some kind of unsightly crustacean elephantiasis as punishment. This claw is armed with preposterously elongated, sharp, black tips that arc across each other like the long, unclipped fingernails of old-school Chinese aristocrats. I’m convinced this outsized pair of meat hook scissors is limited to a single specialized function: carving into the bellybuttons of mortals and removing the very souls from their bodies.

When the Terror-crab asks for a light, you better damn well give that bastard your lighter. Don’t ask for it back. Just leave.

It is perhaps of little surprise that Tasmanian giant crabs are widely regarded to be, mass-wise, the second largest crab species in the world (right behind the Gaunt Sea-nightmare I outlined briefly above)…and that when the opportunity arises, people can’t help themselves from taking photos of these things wearing normal-sized crabs as hats.

If you’ve been looking at Captain Living-Compulsive-Masturbation-Joke up there and thinking that beefy, super-swole right claw would look better split open and dunked in warm garlic butter, then you’re in luck. Tasmanian giant crabs are quite edible and there’s a small-scale fishery of these crabs in Tasmanian waters. However, if you’re a Yank like me, and are hoping to swing by the local Costco and pick up a gut-busting quantity of fresh Pseudocarcinus gigas deliciousness (probably marketed as “Tazzie mammoth crab” or something ridiculous like that), you’re going to be pretty disappointed. The annual harvest of this species is very limited, export tends to be local in scope (basically the rest of Australia and into East Asia), and the boutique nature of the fishery tends to make the crabs expensive (like 50 bucks per pound)….and that’s a good thing. Tasmanian giant crabs, despite their girth, don’t really eat that much or that often, wandering across the muddy ocean bottom, grazing slowly on the occasional carcass, unlucky mollusk, or smaller crab or shrimp. This laid-back attitude towards getting enough food energy to develop means that they grow and mature very slowly. This makes them incredibly susceptible to overfishing, since they can’t replace their numbers quickly. Strict fishing regulations are, fortunately, in place to keep populations from getting depleted.

But, if you were to make a special trip to the northern shores of Tasmania to get your hands on some of that delectable, rare, sustainably-fished giant crab flesh…you could see the second crustacean on this list just by walking inland, up into the wet, thickly-forested valleys of the island. Yes, Tasmania is host to two exceptionally huge crustacean critters, and this one lives in freshwater.

Meet the Tasmanian giant freshwater crayfish (Astacopsis gouldi), which was also known as the “tayatea” to some of the aboriginal peoples of Tasmania.

“On my way to steal your girl…”
(all giant crayfish gifs generated from this excellent conservation-themed short film entitled “Looking After Our Rivers” by Mark Pearce)

These stout, black-shelled, stream-bound lobsters are far and away the largest species of crayfish on the planet. How big are they though? Try THIS big.

Hooooly shit.

Nope. Nope nope nope nope.

At roughly the same size and heft as your neighbor’s cat, Flufferbell, a full-sized, adult tayatea is not only the largest crayfish in the world, but also the biggest freshwater invertebrate, period, currently in existence. In the past, there were reports of these crayfish growing as long as a human leg and heavier than a holiday ham, but these days, most tayatea are considerably smaller…yet still massive and intimidating enough to look more like the aliens in District 9 than something thrown into a pot of jambalaya.

The Tasmanian giant freshwater crayfish is, unsurprisingly, found only on the island of Tasmania. Even more specifically, it natively inhabits only the lowlands in the wet strip of territory at the northern end of the island, and is limited entirely to the streams and rivers in this area that flow north into the Bass Strait (the same body of water where the previously outlined giant crabs are plentiful). However, in recent decades, this range has gotten even smaller, and now the Tasmanian giant freshwater crayfish is typically only seen in fragmented sections of rivers in the northern part of the state. In the past 50 years or so, this strange, lobster-sized crawdad has seen a 70% decline in geographic range and its estimated population size has plummeted to about one fifth of its former glory.

Astacopsis gouldi is as endangered with extinction as it is gargantuan…a direct result of a combination of human influences and quirks of this animal’s biology.

When it comes to having traits that would help ensure survival in a world overrun with smart, hungry, city-raising, forest-leveling, farm-tilling primates, evolution gave the tayatea the shit end of the stick. First off, these giant crayfish are little more than slow, placid, white, succulent protein encased in a mildly inconvenient crunchy wrapper, each one large enough to feed an entire family in a pinch. When large numbers of European colonists began to settle in Tasmania, it didn’t take them long to take advantage of the rivers that were chock-full of living, breathing embodiments of a Cajun restaurant owner’s wet dream. The crayfish were pulled out of the waterways as a delectable and easily-caught foodstuff for many decades by the European settlers, but the harvest wasn’t even close to sustainable. Not even in the ballpark of sustainability. Actually, it wasn’t anywhere near the county containing the street where the ballpark of sustainability is located. It wasn’t necessarily the volume of crayfish taken by itself that was the issue, but the fact that, for the second strike against their luck, much like the giant Tasmanian crabs, the tayatea are particularly vulnerable to overfishing (and for many of the same reasons). Tasmanian giant crayfish take forever to reach reproductive maturity. Most species of crayfish that are collected by humans for food take between one and three years from hatching to finding a crayfish that shares its goals and interests, settling down, losing track of what music is popular these days, and churning out a bajillion chitinous kiddies. But Astacopsis? Males take somewhere in the neighborhood of nine years to get their gonads up and running, while females take something like fourteen fucking years to reach reproductive maturity. This reproductive procrastination is not so much that tayatea are the Peter Pan’s of the crayfish world, stubbornly refusing to grow the hell up and make their mothers into proud (and finally satisfied) grandmothers, but that they are late bloomers; reproductive maturity in crayfish is typically tied closely to size, and tayatea grow incredibly slowly by crayfish standards, and therefore their entire developmental lives are stuck behind a bus on the scenic route. This leisurely growth rate becomes a problem when individuals are pulled out of the population at even a modest pace, because it doesn’t take much to outpace the crayfish’s ability to replenish their numbers. Slow growth and/or maturation rates are a major factor contributing to the population depletion in many other animals (an example that comes to mind are sharks; many currently threatened or endangered species can take more than a decade or two to reach reproductive maturity, and once they do, they may not produce many offspring at all in their lifetimes).

The third trait working against the modern, post-European settlement survival of the tayatea is also associated with how these crayfish make babies. Not only do female giant crayfish take as long as humans to reach reproductive maturity, but once they do, they spend their lives with as much libido as a panda on SSRIs. Females will only spawn every other year (in the autumn), and grip the fertilized masses of eggs underneath her tail and against her legs until the next goddamned summer. That’s right, tayatea eggs take a full nine months to hatch. Even after anywhere between two hundred and one thousand less-than-giant crayfish come into the world, they stick close to Mom for another several months. So, a mature, female Tasmanian giant crayfish spends half her time “pregnant” or babysitting, and the other half not breeding. Fifty percent of her time actively reproducing may not seem that low, but the key is the long period of time our aforementioned lady crayfish spends directly caring for or incubating her single batch of offspring for the two-year cycle. The strategy of Tasmanian giant crayfish keeping eggs and babies on their person for a year at a time is, normally, a fine one. Once at reproductive size, giant crayfish are too large to have any natural predators that would threaten the lives of their clutch. Platypus and some species of fish are known to prey upon younger crayfish, but the big, honking, bowling ball-sized full grown monsters can contently take their time raising up the next generation. Humans, however, have no issue catching and eating adult crayfish….payload of eggs and all. What is normally a perfectly adequate reproductive gameplan, evolved in relative isolation from large crustacean-eating animals, becomes a grave drawback as soon as humans and their appetite for literally anything remotely vulnerable are thrown into the mix.

Historically, it was primarily the swift and unregulated direct overconsumption of these crayfish, enhanced by their slow growth, maturation rate, and long gestation times, that led to their fall in numbers. Since 1998, the harvesting of tayatea has been entirely illegal (without a special permit) in Tasmania, and there is hope that their populations will rebound in coming decades as a result.

However, this species is still at risk of extinction from habitat loss. This is where their fourth unfortunate trait comes in; Tasmanian giant crayfish are, much like that one roommate you briefly had in college, completely unable to compromise on their ideal living conditions.

“No, Derek, I don’t care that it’s ‘Fruit Loop Friday’. Do you want ants? Because this is how you get ants, you weird little shit.”

Astacopsis gouldi is a picky, finicky bastard when it comes to what is and what isn’t acceptable real estate. The streams in which these crayfish flourish need to be shaded with lots of riverside vegetation, and be crystal clear and clean. Preferably, the water should be relatively cold with high oxygen content and negligible amounts of sediment. Basically, if they aren’t sitting in a creek that looks like it was poured directly out of a chilled Brita filter, they ain’t happy or healthy, and will probably die as a result. So, you may be thinking, just keep pollution out of the rivers, and they’ll be fine. What’s the big deal? Isn’t northern Tasmania not exactly a juggernaut of industrialization (which would allow for the opportunity for waterway waste pollution to be a major issue)? Well, there is habitat degradation, but it’s indirect. The cause is large-scale, clear-cut logging operations that occur upriver near the headwaters of these drainage basins. The rivers and streams become swamped with mud and runoff, which chokes out crayfish downstream. Reduction of streamside vegetation (sometimes from direct deforestation, but also as a consequence of flooding and erosion caused by upstream activity stripping the riverbanks of any absorbing vegetation) has the effect of removing shade, which causes the water to heat up past tolerable temperatures, and for oxygen levels to drop (since oxygen does dissolve as easily in warm water). A lack of large plants and trees near these waterways also takes food right out of the mouths of these regal crustaceans. Tayatea consume rotting wood (and the bacteria that grows in and on it) as a major component of their diet. Leaving streams bare, silty, and hot effectively takes away the habitat and food sources of giant crayfish to the point where they cannot adjust, and are simply driven out of that drainage basin altogether. On top of all of this, in lower elevations, habitat loss from humans setting up farmland and diverting water is another strike in the chest of this species. Roads and culverts create additional problems, as they make moving between streams and finding new or adequate habitat next to impossible. So, if you’re ever traveling around the majesty of northern Tasmania, pulling over in your car to gander at the sights and check your map, and you’re feeling just a little too happy with yourself…just think about how the paper map in your hands potentially got its start in a forest up in the mountains, now mulched down to the dirt, leaving scores of crayfish downstream starving, baking, asphyxiating, and disoriented in a milky, dark slurry that was once their pristine home.

If you’re wallowing in impotent self-loathing and the futility of appreciating biodiversity in a dying world clap your hands…

Recovery efforts for this biggest of crayfish are slowed and complicated by a number of factors. Many regions in northern Tasmania are too far gone to hold any hope as a place of reintroduction; the streams having been drained for agricultural purposes a major stumbling block. The majority of the remaining range of this species exists on private land, which is largely used for lumber and agriculture, unsurprisingly, and is largely unfit for tayatea, assuming any high numbers still exist there. The best hope going forward for the Tasmanian giant crayfish comes from the small pieces of protected forestland in the Tasmanian wilderness, immune from deforestation, but until a direct series of measures are implemented to target the preservation and recovery of this species via habitat preservation, it’s uncertain how long they can evade extinction. Effective management will likely require additional behavioral knowledge and population surveys to determine where and how efforts will have the greatest impact. In the end, this tug-of-war between resource development and the health of river ecosystems is very reminiscent to me, as a former resident of the Pacific Northwest, of the convoluted history of salmon and the introduction of dams used to generate hydroelectric power. But, whether or not dramatic actions on par with dam removal will eventually be employed to save the endangered tayatea remains to be seen. I’m cynical, mostly because in the case of the Northwest’s salmon, the fishery is of huge economic interest; protection of habitat is actually of direct human interest. Tasmanian giant crayfish are unfortunately a vulnerable evolutionary curiosity and cannot play the role of “widely-harvested foodstuff”. Perhaps a better comparison between this crayfish’s plight and a threatened critter directly catty-corner across the Pacific is the famously down-on-its-luck (and divisively protected) northern spotted owl, an animal directly threatened by logging and the encroachment of agricultural land, but without an immediately tangible economic benefit gifted to humankind through its continued existence.

It’s worth mentioning that while the Tasmanian giant crayfish is superlatively impressive due to its size, Australasia in particular has quite a bit to offer in regards to unique crayfish. Mainland Australia, Tasmania, and New Guinea are a global center of crayfish diversity, with more than 150 species of crayfish patrolling the brooks and rivers of Australia alone. In particular, one family, the Parastacidae, is diverse and widespread across Australia. The family is known only from the “southern continents” (Australia, South America, southern Africa, and Madagascar), having a “Gondwanan distribution” (referring to the supercontinent of Gondwana, which was made up of these southern continents plus Antarctica, breaking apart nearly 200 million years ago). The Tasmanian giant crayfish is a member of this family, as is another sizable crayfish, the Murray crayfish (Euastacus armatus). It is found through much of the lower stretches of the Murray and Murrumbidgee Rivers in southeastern Australia, and grows to lengths of over a foot, making it the second-largest crayfish species in the world, beaten out by its close relative from the island of Tasmania. It’s a pale-clawed, thorny creature that looks like it crawled out of a pixelated puddle in the Super Mario Bros universe. It, like the Tasmanian giant crayfish, has suffered range reductions and population shrinkage as a result of fishing pressure.

All the colossal crustaceans mentioned above are either primarily, or entirely, aquatic. Their immense bodies are supported by water, and when pulled to the surface, despite their impressive/terrifying appearance, they can do little more than weakly flip themselves on their back and wave their useless legs like an air traffic controller on barbiturates. They are fine-tuned, armored machines when submerged, but when they feel gravity’s full effect and the desiccating air on their gills, they suddenly have the grace and energy of a hungover vertigo-sufferer trying to haul themselves out of a bathtub.

However, one species of crustacean has looked at the shimmering ceiling of its watery world, girded its loins, and taken the landlubber life by storm. This crustacean is not only the largest terrestrial crustacean in the world, but it is also the largest arthropod (the taxonomic phylum that contains everything from insects to centipedes to shrimp) to skitter about in the dirt in modern times. They are known by many names across their geographic range, including ‘coconut crab’, ‘robber crab’, and ‘palm thief.’ In the Mariana Islands and Guam, it is known as ‘ayayu.’ In the Eastern Caroline Islands, it is called ’emp’, and in the Cook Islands, it is called ‘unga’ or ‘kaveu.’ All of these names describe Birgus latro, an animal that looks like a combination of evolution’s take on the chitterskrags from the Dungeon Siege games and something that I’m pretty sure plants nightmares in your brain by whispering ever so softly in your ear as you sleep.

“Sshh, rest your head, delicate, mortal creature. May your slumber be….fruitful.”

These terrestrial crabs are found widely across the tropical Indo-Pacific region, ranging from the island of Zanzibar off the coast of East Africa at the western edge of their distribution, through the Indian Ocean and the scattered islands of the West and South Pacific. Despite their wide range, coconut crabs are fairly rare in areas with large human populations, with their largest populations situated in isolated island chains and coral atolls out in bumfuck nowhere in the middle of the goddamn ocean. The reason for this is almost certainly because humans are eating these critters out of existence wherever enough humans establish and overlap with crab’s territory. In fact, it is thought that they, at one time, were also found on the Western Indian Ocean islands of Mauritius and Madagascar, as well as the Australian mainland, but that humans in these areas simply om nom nomed them into a state of localized extinction (it’s also curiously absent from the Hawaiian Islands for an unknown reason, and when one recently turned up wandering aimlessly through Honolulu just down the road from where I live, the public/media response was one primarily concerned with its invasiveness…although it’s also possible it existed here before Polynesian colonization).

Perhaps this ‘extirpation by digestion’ is understandable, considering that in the tropical island locales that these crabs are natively found, there isn’t much food to eat anyways, so local populations would force themselves to dare subduing and splintering open an alien horrorshow that looks more like a demon-possessed Pokemon than a meal. But, there must be some other reason humans would risk cracking open something that looks like it scrambled out of a fresh, mysterious, meteorite impact crater. There is. Coconut crabs are easy to catch, and, despite looking like they having nothing inside but the souls of thousands of missing children, they are, in fact, full of succulent, delicious flesh. Shitloads of it. Because, as I said above, they are really big. And, to drive home what it means when I say “largest land-living arthropod on Earth”, I’ve included this oft-shared image of a coconut crab forever enshrining a newfound appreciation for the good, normal, God-fearing, nocturnal, unsanitary, kleptomaniacal mischief of raccoons.

I’ll take squealing, furry balls of teeth and rabies over an honest-to-Christ living Ray Harryhausen creature effect, thanks.

Coconut crabs, at their largest, can have a leg span of three feet and weigh as much as a 12-pack of whatever alcoholic beverage you’ll need to pound down to deal with this information. If you’re visiting one of the areas where coconut crabs live, and you think you can avoid seeing one of these guys by just skipping the beach, well, I’ve got news for you; coconut crabs are fully terrestrial, can march their creepy asses several miles inland, and are surprisingly, terrifyingly nimble over open ground. Also, did I mention they can climb trees? Because that’s sort of a thing they are known for. Shimmy-ing your quaking knees up a palm tree is a pretty fucking futile escape tactic. But remember, if you’re thinking at this point that your god has forsaken you and that surely these abominations are the incarnations of Old Scratch himself, know that they are NOT one in the same; one is an ancient, uncaring reservoir of malice and betrayal, a twisted being descended from a regal lineage…and the other is Satan.

Well, at least one of them is a shiny.

Birgus latro‘s unsettling size and otherwordly, death-spider appearance has been acknowledged mostly by, admittedly, comparatively hysterical and easily-petrified Westerners for a while now (the people of the tropical Indo-Pacific that lived alongside coconut crabs largely regarded these animals as delicacies and aphrodesiacs). In particular, coconut crabs were forced into the consciousness of American life during the Second World War when Allied forces were scattered across much of the West and Central Pacific, and American soldiers came in contact with these armor-plated monsters on their remote island outposts. The impact coconut crabs had on these men can be seen in the stories and imagery that made it back home in the decade after the War. For example, this was a beast so unnerving, apparently, it inspired artwork (and associated tales of terror) featured in hypermasculine, vintage “men’s adventure mags” in the 50s, much like the George Gross piece below, which was featured on the cover of the November 1956 issue of Man’s Conquest. For context, this was a publication so devoted to stories of egregiously haggard badasses upholding Man’s glorious dominion over nature by shooting, spearing, roundhouse kicking, or otherwise dispatching a veritable zoo of inexplicably numerous and murderous wildlife that I’m half-convinced the magazine owes its existence to the ghosts of Teddy Roosevelt and Ernest Hemingway aggressively ejaculating onto a stack of blank pages. The 50s and 60s were….uh….a different time.

“Christ Almighty! These are the second-worst crabs I’ve ever had to deal with…next to the ones I got from that dame the last time I was in Tijuana with the boys!”

The coconut crab’s great size becomes even more impressive when you consider the evolutionary history of this crustacean, and all the truly unique adaptations and modifications to its physiology that have been driven by natural selection.

Birgus latro is literally one of a kind. There is only one known species in the coconut crab genus, and its closest living relatives might not be what you’d expect. Rather than its nearest kin being other big, brutish beasts like the other “giant” crabs and crayfish I’ve gone over earlier in this blog post, the coconut crab comes from diminutive stock. Coconut crabs are actually a variety of ludicrously huge, highly-derived, “homeless” hermit crabs. Coconut crabs are members of the family Coenobitidae, which includes a single other genus (Coenobita). Coenobita hermit crabs are notably robust and very capable land-dwellers themselves, but of course, the elephantine black sheep of the family takes this to a whole other level. The family resemblance is still quite there, and this is especially true when you pull down the coconut crab baby photos from the attic. Juvenile coconut crabs, following a larval stage in the ocean, are functionally the same as Coenobita hermit crabs. In their youth, coconut crabs hold onto their heritage tighter than a woefully misguided South Carolinian waving the Stars and Bars; they cover their soft hindquarters by retreating into, and carrying around, a snail shell. It is only after they have grown larger, too large for any shells or even coconut halves, that they forgo their protective training wheels altogether and start strutting about in a thick, desiccation-resistant carapace. I was in the Republic of the Marshall Islands (a Micronesian nation of coral atolls in West Pacific) earlier this year, and I saw a young coconut crab on a beach on Arno Atoll without even knowing it. At the time, I assumed it was a Coenobita species, but it was months later when I was looking at the photos and attempting to identify the species that I realized no native hermit crabs were a match, and the coloration was a dead wringer for a fledgling Birgus latro. The one I happened across was using an ill-fitting piece of plastic pollution as a shell, which should have tipped me off, considering that everyone knows that, of the two crab groupings, young coconut crabs have the inferior sense of fashion.

You’re wearing plastic? Really? Hydrocarbons are SO last season.
Photo: Jake Buehler

So, coconut crabs are just hermit crabs that hit the gym and creatine powder really hard and ditched the mobile home to grin and bear it out in the big, harsh, idyllic, balmy, sunny, white sand beaches. It’s worth observing that hermit crabs, as a group, aren’t really “true crabs” either. They belong to a division of crustaceans (an infraorder, in this case) called Anomura (meaning “differently-tailed”), whereas “true crabs”, which include all the crabs you are likely most familiar with (including the giant Tasmanian crab), are in the infraorder Brachyura (“short-tailed”). Other Anomurans include squat lobsters, mole crabs, and king crabs (which includes this star of Deadliest Catch). Anomura and Brachyura are thought to be “sister groups”, meaning they share a common ancestor more recently than with any other similar division of crustacean.

Outside of their size and libertine views on hermit crab domestic traditions, coconut crabs have evolved a number of traits that not only make their terrestrial lifestyle possible, but required. For one, coconut crabs have modified their gills into a brachiostegal lung, which consists of gill tissue with a high degree of surface area to allow absorption of oxygen from the air rather than from water. The setup, not unlike the interior workings of your own respiratory system, must be moist to function well. However, unlike you or I, the coconut crab doesn’t have a whole series of cavities and sinuses and tubes to facilitate the retention of moisture, so it uses a rather crude (but effective) method: wetting its legs in a puddle and stroking them over the convoluted lung tissue. Although these lungs need to be constantly spritzed, this doesn’t mean an adult coconut crab can breathe in water just as easily as in the air. Their branchiostegal lungs are indeed lungs, and a submerged coconut crab is guaranteed to drown. Adult coconut crabs are so incapable of dealing with water that after mating on land, the female carts around the fertilized eggs underneath her tail until right before they hatch, and when the time is near she makes a trip down to the water’s edge with the haste of someone hunting down a public restroom after a gastronomically reckless episode with a gas station burrito. There, she can wash her young into the surf at high tide while hardly getting wet.

Coconut crabs have a varied and entirely terrestrial diet, which, as you’ve likely guessed, includes coconuts. These crustaceans really can, and do, break through the tough exteriors of coconuts to eat the nutritive white flesh on the inside. It sometimes takes the work of more than one crab at a time, but they are more than capable of using their strong claws to strip away a coconut husk like you would feverishly denude a Kit Kat bar of its wrapper (and by you I mean me…far more often than I’m proud of). Breaking apart the inner core occurs in small pieces, and splitting the whole thing open can take days, but an animal with a brain the size of bouillon cube can do it with its bare hands and that’s more than I can say for myself. If coconuts aren’t already sitting on the ground, and a coconut crab is in the mood for some Mounds and piña colada action, the hungry bastard will summon its inner Sylvester Stallone ala Cliffhanger and clamber an incredible thirty some-odd feet up a palm tree to snip a coconut down for a snack. Most coconut crabs don’t bother to edge their way back down the tree trunk, and opt to just flop gracelessly onto the ground below, which doesn’t appear to harm them. Also, just a friendly reminder, getting hit with several pounds of falling coconut, or eight pounds of falling, giant fucking wanna-be monkey crab, can cause serious injury or death. While incredibly unlikely to ever happen, the coconut crab is, via aerial, kamikaze assault, theoretically the only crab on the planet that could (inadvertently) kill a human being.

All this being said, in reality, coconuts don’t make up the bulk of the coconut crab’s diet.

Its favorite food is….TV show hosts! Run Brian Cox! Run for your life!

Coconut crabs have a surprisingly varied diet. Much of their caloric intake comes from fallen and decaying fruit, but they also regularly seek out and indulge in carrion, as well as small reptiles, mammals, and even other crabs. Truthfully, if it’s stationary, or unwary enough to be captured…there’s a good chance that these guys are already on it. Their garbage disposal habits have made coconut crabs, to some, the potential reason why Amelia Earhart’s remains may have never been found; the idea being that if her plane went down over an isolated atoll, and she managed to survive long enough to make it to land only to die later, her body would have been consumed rapidly by coconut crabs. Some dubious records of a partial skeleton from the early 40s in Kiribati, along with other bits of evidence, have fed into the idea that this was Amelia’s final fate. But, it is far from settled, with much of the story’s claims of crabs carrying off and burying her bones like a pack of the weirdest dogs in the world not being supported by any behavioral evidence in these creatures.

As scary as coconut crabs are up close, in one-on-one combat, the worst they can inflict is a nasty, vice-like pinch. They, like every other crustacean in this list, is far more in danger of being boiled, broken, and buttered by humankind. Perhaps it is telling that even the largest, most physically imposing representatives of an entire taxonomic class are still outmatched by our species’ appetite, and that we have the ability to literally eat entire populations (or whole species) into oblivion. It would do us, and the world we inhabit, some good to be aware of this unbalanced power and privilege.

Image credits: Intro coconut crab image, Japanese spider crab, giant Tasmanian crab closeup, giant Tasmanian crab gif (clipped from this video from Eaglehawk Dive), giant Tasmanian crab with lighter (Paddy Ryan), man in cereal tub (Getty Images), coconut crab on forest floor, coconut crabs in trees, Man’s Conquest cover (George Gross)

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