Category Archives: Evolution

Mesmerizing Marine Mimics: Fooling Across Phyla

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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.

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Mesmerizing Marine Mimics: Counterfeit Malicious Fish

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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.

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Claws: The Ultra-Jumbo Class of Crustaceans

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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.

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Venomous and Underrated: Hymenopteran Horrors

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I have a penchant for particularly noxious lifeforms, the ones that have evolved nasty chemical tools for either fending off bigger, badder, and hungrier things, or bringing down breakfast. Anyone who has read the breadth of this blog should now be aware of my adoration of the biology of such fundamentally antagonistic critters, the mark of which has been left behind in the number of entries devoted to the lesser-appreciated toxic flora and fauna of the world. Deadly, toxic mushrooms. Boxfish, with their poisonous mucus. The terrifying, seafood-driven, hallucinatory rollercoaster ride of ichthyoalleinotoxism. Pungent vinegaroons and acrid harvestmen. Venomous caterpillars that make you bruise like a peach….to death. Birds that silently embed concentrated toxins in their fucking feathers.The “Do Not Touch” exhibit in the Museum of Life has made a strong showing within the overall theme of Shit You Didn’t Know About Biology. I mean, Christ, my very first post on here was about an insatiable aphid-slaughtering deathdozer that bleeds poison foam.

Most of the unsavory representatives above are of a particular variety of being, well, molecularly disagreeable. Up until now, I’ve chiefly yammered on about “poisonous” and “toxic” organisms (with the exception of that intimidatingly venomous caterpillar), things that secrete or store harmful compounds in or on their bodies, such that the aggressor the poisons are intended for must passively absorb the toxins through digestion, or through the skin and mucus membranes (considering my research on boxfish, this bias towards this type of defensive strategy shouldn’t be all that surprising). Nature also hosts plenty of “venomous” organisms, which entails a much more direct, Type A approach to chemical warfare, wherein the poison punch is forcefully injected via a (generally quite pokey) delivery system that has evolved specifically to fuck up your day.

There are plenty of well-known venomous superstars, and it is especially the venomous snakes and spiders that garner the lion’s share of the limelight. A fair number of people are familiar with the superlatively deadly representatives of these groups, from sea snakes, cobras, and taipans, to Brazilian wandering spiders and Sydney funnel-webs, which regularly make appearances on just about every heavy-handed, suspense-saturated, kitschy “TOP TEN DEADLIEST” daytime special to run on Discovery, Animal Planet, or Nat Geo for the last decade or so.

But the brush painted by the evolutionary strategy of venom is broad, and the technique has cropped up in a surprising number of very distantly related lineages. This two-part series of posts will be devoted to the unsung venomous animals, which neither slither through the grass or canopy (nor thwart the professional efforts of John Goodman), and within their ranks, not even necessarily the most dramatically dangerous or traditionally telegenic and charismatic representatives. These other animals, however, have evolved injectable weaponry that is truly remarkable on its own merits, by a diversity of metrics, despite not achieving comparably towering levels of renown. Much attention has been bestowed upon the black mambas and black widows, the Clooneys and Jolies of venom notoriety. It’s appropriate to give the Goldblums and Leguizamos their day in the sun for once.

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Arachnids: Solifugids

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This post is the fifth in an ongoing series on arachnids. Previously, this series addressed whipspiders, hooded tickspiders, pseudoscorpions, and harvestmen. Additional posts on other weird, often overlooked or neglected groups of these creepy crawlies to follow. For a related chelicerate, but as far as science can tell, not an arachnid, see the post on sea spiders.

The solifugid.

This group of fleet-footed arachnids is known by many names across the globe. Wind scorpion. Camel spider. Sun spider. Sun scorpion. Unintelligible screaming and cursing. All of these refer to members of an enigmatic order of arachnids; Solifugae. The name of this order, derived from Latin, means “those that flee from the sun”, an acknowledgement of their habit of chasing shadows in an attempt to stay cool in their predominantly hot, sunny, and arid native habitats. Despite their frequently used common names which identify them as some sort of breed of spider or scorpion, solifugids (a more accurate identifier of the arachnids within the Order Solifugae) are most certainly a distinct, separate animal from either group. They may have the long, athletic legs and noticeable jaws of spiders (Order Araneae), and the elongated body, coloration, and desert aesthetic of the scorpions (Order Scorpiones), but the 1,000 species or so of solifugid occupy their own lonesome twig on the arthropod family tree. It is generally thought that Solifugae is a part of a larger subdivision of arachnids, called Dromopoda, which also includes scorpions, pseudoscorpions, and harvestmen (daddy longlegs); specifically, combined analyses of the genetic relatedness and shared morphological features of these critters have also linked scorpions, pseudoscorpions, and solifugids together in a grouping dubbed “Novogenuata.” Although, comparative studies on the male genital system have also suggested that solifugids might have a more complex evolutionary history, showing more similarities with mites and ticks in some ways than with their supposed close relatives, the pseudoscorpions. This confusion of what makes a solifugid a solifugid, and its relationship with the rest of the arachnids, would be greatly assisted by fossil evidence, but the fossil record for the Solifugae is pitifully scant, with a few dubious, incomplete, vaguely solifugid-like specimens dating back to about 330 million years ago…and only a few instances of unambiguous solifugids showing up about 300, 115, and 50 million years ago. Most importantly, the earliest stages of this group’s evolution are currently lost to us.

Whatever they are in the grand architecture of the arachnid clan, they are widespread, gravitating towards hot and dry regions of the subtropics and tropics the world over, omitting their presence from only the continents of Antartica and, surprisingly, considering they would fit right the fuck in there…Australia. And wherever they make their residence, they have a very powerful effect on the humans that encounter them, and they have for an incredibly long time. Solifugids, to put it lightly, have an “imposing” appearance and demeanor, with their huge, sharp, pinching jaws, sizable mass, and ungodly overland speed. Consistent first impressions full of everything ranging from a bad case of the all-overs to panicked, wild boot-stomping has undoubtedly earned them immediate recognition as a being assuredly, terrifyingly divergent from other many-legged beasties since antiquity, with the Greeks dubbing the monstrous arachnid “phalangion”, decidedly separate from “arachne”, the spider. More recently, there are accounts of soldiers stationed in North Africa during both World Wars who would pass the time by pitting captive solifugids against each other, or against a scorpion (because why not, I guess), in a fight to the death in possibly the smallest, ugliest, and leggiest gladiatorial showdown of all time.


I’m thinking a 6-inch tall Joaquin Phoenix will give the scorpion a thumbs down.

These brutal spectacles involving dueling “jerrymanders”, another name for the solifugids, were enthusiastically gambled upon, because of course they were. Also, in regards to the aforementioned moniker, if there’s any animal that I could envision being spiritually associated with the deceiptful, ethically impoverished, slimy act of manipulating voting districts, it’s the solifugid…an animal that looks like it would skitter up your leg and chew and burrow its way into your taint if you so much as looked at it sideways.

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Armed to the Teeth: Bites from Forgotten Sharks

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As the 31-day stretch of August rapidly rushes to completion, and the balmiest days of summer fade into the imminent, cool veil of fall, 2014 also discards one of its temporal landmarks associated with these heat-stricken days. If you think I am referencing something remotely anapestic and evoking chest-fluttering nostalgia of long-forgotten, canicular childhood summers, then think again. Because I am, of course, talking about Shark Week.

Yes, that now-legendary bit of the Discovery Channel’s summer programming line-up, a selachimorph-centered festival that is closing in on three decades running, has now passed us by, ending but two weeks ago. Years ago, Shark Week initially appeared to be driven with the mission statement of Discovery in mind, one rooted in the dissemination of fundamentally educational, science-based material in an entertaining manner. This incarnation of Shark Week was the one I was fortunate enough to grow up with, and this week was a boon to my insatiably science-curious child brain, one that my neurons practically salivated over in Pavlovian form right around the time the last traces of abandoned, burnt out firecrackers left July’s dirt. The gift of science education excellence was instrumental in the development of my eventual fascination (and career trajectory) with biology, and I credit the old-school Discovery Channel’s programming with much of the inspiration and intrigue about the natural world that gilded my early days.

At the age of four, my shark ID skills were solid. However, my artistic skills were still…er….buffering.

So, given the intimate intellectual relationship I have with Shark Week and Discovery, watching what both entities have become in recent years feels like a steel-toed kick to the kidneys. There are a laundry list of offenses, and all of them hit on a single formula; the sacrifice of ethics and scientific accuracy in favor of mythology and adrenal-gland massaging codswallop; a grand invasion of heart-pumping, flash and sparkle nonsense programming based on approximately zero micrograms of actual science, all as an ill-conceived motion to inflate ratings. Some examples of Shark Week contrived falsehoods? Well, there’s this lovely bit of mass hysteria-inducing, publicity-hungry deceit initiated by cries of “oh no! Lake sharks! *wink wink*.” Also, there’s that time Discovery trotted out this steaming, embarrassingly unscientific pile of horseshit. Oh, there’s also that other time they made an entire special up. Or how about how the network can only seem to convince scientists to do Shark Week specials with them if they straight-up con them into doing so?

Others (linked above) have done a splendid job of calling out the network’s recent, fraudulent Shark Week habits, so this post isn’t going to be yet another dart in that already well-pockmarked board, but what I want to address is loosely tied to Shark Week’s newfound adoration of Megalodon (well, specifically an adoration of tricking viewers into believing the very extinct shark is still patrolling the deep…now for two years in a row).

“Megalodon”, or to be more accurate Carcharocles megalodon (or Carcharodon megalodon, it depends on what paleontologist you ask) is a popular beast, and thus is an obvious choice for many an examination by television networks (in mockumentaries or not). The extinct shark species is popular for damn good reason, too. C. megalodon was an animal of such outlandish proportions that it doesn’t seem like it could ever have existed, and yet it did, for more than 26 million years, dying out right around the time our ancestral line first harnessed that hot, orange, light-producing stuff that eats up wood (followed swiftly by the invention of S’mores and crappy ghost stories). This was a shark that, according to the most conservative estimates, exceeded 45 feet in length, and had a pair of cartilaginous bear trap-esque chompers big enough to gulp down a Ford Fiesta without even scratching the paint on its immense, triangular teeth.

And oh yes, those teeth. Those frisbee-sized blades that festooned its jaws in a ragged chain of despair. Those famous teeth, for which the animal is named (megalodon basically means “giant fucking tooth”), combined with a body bigger than a goddamn school bus, have enraptured the imaginations of young and old alike, and contemplation about what it would be like to encounter such a surreal, monstrous animal in the flesh is unavoidable.

But, here’s the deal with ol’ Megs…outside of its status as by far the largest shark that ever lived, and definitely one of the biggest predators to ever exist (getting edged out by the sperm whales alive today)…as far as we can tell, there’s nothing insanely unique about its biology. Granted, one of the most fascinating things about C. megalodon is that we don’t know that much about it. Even the size of the thing is sort of up in the air, seeing as how the scientific community has only fragmentary remains (teeth and a handful of vertebrae; the cartilaginous skeletons of sharks don’t fossilize as readily as bony skeletons, so this dearth of recorded remains is not that unusual) from which to base their calculations; estimations range from the 40s of feet in length to more than 60 feet…which in my book is the difference between “we’re going to need a bigger boat” huge and “I’m going to need a new pair of pants” huge.

Honestly, C. megalodon was cool and all, but it was basically just a Hulked-out version of any large lamniform shark (Lamniformes being the order of sharks to which great whites and makos belong). The animal is more or less like a great white had a run in with Rick Moranis and his growth ray, with maybe some very subtle differences in proportions…and a slightly different taste in prey…like taking on goddamned whales instead of comparatively diminutive sea lions. Yes, C. megalodon was something of a specialized whale killer…a shark exquisitely well-adapted to slaughtering and consuming the most massive animals of all time.

So sure, it’s teeth were heart-stoppingly big, and robust, and belonged in the titanic jaws of a beast of celebrity status….but they were just relatively standard lamniform teeth ratcheted up in size, with some limited modifications for slicing through several hundred cubic feet of whale flesh and bone at a time (increased thickness and bigger, deeper roots). For an animal so well-known for its mouth, it certainly didn’t have the most unique pearly whites among extinct sharks. The diversity of prehistoric sharks, and the diversity their feeding adaptations (which often are very divergent from today’s sharks), are woefully unappreciated, at least in comparison to C. megalodon, which is a remarkable shark due to its size and power…but I can think of a couple examples of long-extinct sharks that have far more interesting things going on at their eating ends.

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Evolutionary Anachronisms

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The avocado.

You may think you have a good relationship with the avocado. The buttery fruit of this plant may regularly accompany your turkey sandwich, sliced and fanned out across the bread. Or, it may serve as a hearty dip in the form of guacamole. More recently, avocado is seemingly being utilized in a greater variety of ways, being deep-fried, thrown in macaroni and cheese, and finding its way onto burgers, Subway sandwiches, and even into ice cream. You’d expect that with all this attention, our green-fleshed, knobby-skinned friend, the avocado, would be content with its current role in human culinary efforts.

However, the avocado may very well be lonely.

Despite all our affection, this loneliness stems from the avocado potentially having eyes for another. I mean this, of course, in the sense of the concept of co-evolution (which I examined in a previous post), which is directly tied to the reproductive role of the fruit itself. The main function of a fruit (a botanical fruit, typically meaning the structure derived from the reproductive tissues of the flower housing the seed(s)), is to move seeds away from the parent plant and into areas that promote growth and survival. Many types of adaptations in fruits exist to help achieve this goal of seed dispersal; from the wind-catching dual blades of maple tree fruits (known as samara), to exploiting the appetites of the ubiquitous (and notably mobile) animals in the neighborhood. This latter evolutionary strategy involves the development of fruits that enrapture animal taste buds and provide irresistible caloric value, allowing consumed seeds to travel safely inside the gut of an unwitting, far-traveling chauffeur until being excreted away from the crippling shade of the parent plant. This is called “endozoochory.”

Most endozoochorous fruits have evolved to be eaten by fairly specific animals. Predictably, fruits adapted to be taken by songbirds are going to have different physical attributes than those associated with insects or elephants. You can try and fit a peach pit through the body of a sparrow, but you aren’t going to get very far. Similarly, expecting tiny, thin-walled seeds to withstand an elephant’s battery of grinding teeth isn’t realistic either. The suite of fruit traits evolved for dispersal by a given group of animals roughly categorize into “seed dispersal syndromes.” By interpreting these syndromes, we can often get a good idea of what the primary dispersing animal, the other partner in a co-evolved relationship, is likely to be.

In light of this, it becomes obvious that despite our love of the avocado (specifically, domesticated cultivars with lots of flesh; wild avocado fruits have a thinner layer of green deliciousness surrounding that pit), it is not “meant” for human consumption and seed dispersal. Any attempt to chew up the whole fruit and swallow the massive pit is bound to land your asphyxiating ass in the cemetery. However, the situation for avocado’s seed dispersal isn’t much better in its wild Neotropical range. Many smaller animals (like monkeys) that partake in avocado consumption are “pulp thieves”, ingesting the oily layer and tossing the seed at the base of the parent tree. In fact, no native animal is known to consistently and effectively disperse wild avocado. Why then does the avocado make a big, energetically expensive fruit that doesn’t cut the mustard on dispersal? Also, who is the true “buyer” of avocado’s product?

The answer to both those questions may be that the avocado’s chief dispersal agent is extinct. Kaput. Gone. Effectively an “ex-animal.” This would mean that the avocado fruit is an evolutionary anachronism, equipped with traits fine-tuned by evolution for interaction with a species that has quite suddenly disappeared, leaving the once perfectly capable seed vessel under-appreciated and inadequately used.

“Fruit’s almost ripe, guys. Come and get it! Hello? ….Guys?!”

It’s a very serious case of being all dressed up with nowhere to go.

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Metatherians (Part 2 of 2): Odd Living Representatives

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…so, some more about those metatherians/marsupials.

In the previous part to this two part series, I went over some of the now-extinct metatherian megafauna that once graced Australia and South America. These animals were fantastic and marvelous pinnacles of metatherian specialization, yes, but there are plenty of surviving metatherians, all of them of the ‘marsupial’ clade, that are also largely ignored and their lives obscured. There are some truly bizarre and amazing marsupials outside of the traditional koala/kangaroo/wombat/possum group that essentially everyone on the planet associates with the marsupial infraclass, and all of them somehow survived invading hoardes of humans and other placental species (although, in most cases, just barely).

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Metatherians (Part 1 of 2): Extinct Megafauna

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Marsupials.

The immediate association most people have with the term ‘marsupial’ is that of fantastical, adorable, fluffy beasts in the far-away magical land of Oz, equipped with built-in fanny packs for storing their tiny, even more adorable, offspring. Bounding, big-eared kangaroos, sleepy koalas, and perhaps a hyperactive sugar glider or a waddling opossum might cross their minds. Not too far beyond this is where the train of thought pulls into its final stop, and suddenly they’re caught up in the romanticism of Australia itself; the sun-baked, tawny Outback scabland, didgeridoo droning in their mind’s ear, impossibly colorful fish flitting about the Great Barrier Reef, and perhaps Hugh Jackman or Nicole Kidman (whatever their fancy) driving cattle across the Northern Territory during The Dry.

While this idealization is all well and good, there is actually a lot more to these pouched animals than what fits on the in-fold of a Qantas brochure.
Marsupials are really bizarre by mammalian standards, and have a rich and relatively unrecognized evolutionary history that spans back 125 million years. This entry is one of two that will be devoted to these weird little creatures, focusing first on their unrealized illustrious past, and then on lesser known representatives of their clan in the present.

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Dragons

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Dragons.

We’ve known them as ancient, mythical, winged, pyromaniacal reptilian beasts with a flair for the dramatic and destructive. They have been a fixture in our lore, in some form or another, the world over. While most of these tales of dragons are fictional, or at least highly embellished, there is still a very strong chord of truth in them. The blaze-setting, screeching hell-drakes so common in storybooks have not existed for a very long time, and it is unlikely that Medieval humans actually had contact with them (this stands in contrast with unicorns, which went extinct in 1982 when the last specimen escaped from her enclosure and ingested some antifreeze). However, dragons have had a rich and colorful evolutionary history that dates back 225 million years, and their unique biology and rise and fall in biodiversity is worth discussing.

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