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.

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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.”

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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*

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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).

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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.

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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.

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