The Octopus That Does Incredible Impressions of Fish and Snakes

No schoolyard insult is more dreaded, more cruel, more head-turning than calling someone a copycat. Copycatism is adolescent plagiarism, through and through, and potentially devastating to one’s social standing. But in the animal kingdom, natural selection loves a copycat. Being something you’re not could well keep you out of a stomach.

And no copycat is stranger or more accomplished than the mimic octopus. True to its name, it impersonates a variety of other animals on the fly, morphing from an octopus to a banded sole to a lionfish to a sea snake. But this is no random assemblage of impressions: All of these creatures are toxic or venomous. The mimic octopus isn’t just a copycat—it’s a copycat that’s evolved a strategy far more brilliant than would appear at first glance.

Long ago, the ancestors of octopuses, and indeed the ancestors of all other cephalopods like cuttlefish and squid, took refuge in the safety of their shells. Then something went awry—perhaps a more powerful predator appeared that could make short work of the shells—and the cephalopods were forced to evolve more novel defenses (the nautiluses are the only cephalopods to have retained their shells). The cuttlefish, for instance, is a master of camouflage, blending seamlessly with its surroundings, while squid opt for sheer speed or, you know, growing to over 1,000 pounds in the case of the colossal squid.

But the mimic octopus—not to be confused with the similarly striped but even-better-named wonderpus—has in a way adopted the defenses of venomous and toxic creatures it shares a habitat with. “When they swim up into the water column and hold all the arms around them,” says marine biologist Mark Norman of Australia’s Museum Victoria, “that I believe is mimicry of a lionfish with its banded spines.” And lionfish are not to be messed with. Their dorsal spines deliver a venom powerful enough to cause breathing difficulties in humans.

A mimic octopus making its getaway while impersonating a lionfish. It is still unclear how lionfish feel about this sort of sendup.

During all of this mimicry, the octopus is not only contorting its body, but transforming its color to fit the part. This is a famous trick of the cephalopods (oh, and that cranky dinosaur in Jurassic World that was laced with cephalopod genes because are you kidding me), and it’s all thanks to cells called chromatophores. Muscles open and close these sacs of various colors, allowing the octopus to rapidly change its hue from a pale sandy color to those noisy black and white stripes—and everything in between.

When the octopus is down on the seafloor it seems to mimic at least two other not-to-be-trifled-with critters. One is the banded sole, a variety of flatfish that looks a bit like a flounder, only it has poison glands at the base of its fins. For this impression, the octopus pulls all of its arms back, forming a sort of teardrop, and jets over the sand.

The other animal is a snake called the sea krait, whose wildly powerful neurotoxic venom can kill you (it’s actually docile and its deadliness isn’t its fault, to be honest—it needs be able to quickly incapacitate the fish it hunts or the things will just swim away). To mimic this one, the octopus shoves six of its arms into a hole in the sand and holds its other two out, giving them a slight wiggle.

Here a mimic octopus impersonates a sea snake as a fish is all like “eh never mind.”

Now, the octopus doesn’t just throw that snake impression out willy-nilly. It deploys whenever a particular kind of fish starts getting up in its grill: the damselfish, which is a favorite prey of sea kraits. This suggests that the octopus actively chooses which mimic works against which potential predator.

And that seems to fit right in with science’s conception of octopuses as particularly intelligent—except that’s all a bit problematic. “Intelligence is a really difficult issue with octopuses,” Norman says. “I’ve gotten into trouble before by saying most of the tests on octopuses demonstrate the lack of intelligence in the researchers.”

The thing is, the notion of intelligence is a human construction, and what might be smart for people isn’t necessarily smart for animals. So what tests should scientists give to octopuses? Having the creatures solve mazes is nice and all, but it’s not like octopuses are scurrying about mazes in nature.

That’s no banded sole–it’s a mimic octopus that wishes so bad it was a banded sole.

“I think our biggest problem is that we almost give an English language test to an octopus,” Norman says. “I think we’re failing to ask the right sorts of questions, or understand the nature of the intelligence or the kind of sharpness of their responsiveness.” (That said, Norman has seen other octopus species pull off incredible tricks of their own, such as one octopus that cleverly faced down an intruding bristle worm. The octopus couldn’t attack the intruder directly, what with the bristles and all, so it tried pushing the worm away with a wave of sand, kind of like a bulldozer … with eight too many arms.)

Of course, it would seem smartest for the octopus to hole up in a crevice like other octopuses. But their mimicry may have evolved in a very “smart” way to help the octopus procure food, not just avoid becoming it.

A creature would be a damn fool to venture out on the seafloor in daylight without some sort of defense. So the sea krait has its deadly bite, which doubles as an offensive and defensive weapon, while the lionfish has its spines. And they advertise this unpleasantness with that wacky-ass Beetlejuice coloration, scaring off predators so they can roam freely looking for food.

By aping these creatures, the mimic octopus muscles into a market few other octopuses can. “It’s colonized the most dangerous habitat you could have as a cephalopod, in that you’ve got very little in the way of defenses and you’re just meat walking around, very edible,” says Norman. “They’ve found a way to forage over those environments during the daytime, relying solely on their capacity to deter predators by their similarity to other species.”

Read more at Wired Science