Can animals evolve to be shape-shifters?

The Short Answer: Interesting question, Alexander, and thinking about this question just a couple days after Halloween seems appropriate. My first impulse was to say, “Of course not!” But then I started thinking a little more …

First, let’s decide what we’re talking about. In my less than extensive experience with science fiction and fantasy literature, it seems to me there are two basic types of shape-shifters. There are aliens who can take on the shapes of different animals. And there are aliens who can mimic humans, either generic people or specific people. I think we can agree that there are no animals that can do these things on earth presently … at least we don’t think so …

frog metamorphosis

monarch metamorphosis

Which is not to say that there aren’t some impressive body transformations we know about. Think of a tadpole changing into a toad. Or a caterpillar changing into a monarch butterfly. In both cases, body shapes are changed and internal organs are rearranged. And if you didn’t know in advance, if someone handed you a fishlike, water-living tadpole and said it would change into a dry-land-living four-legged toad, you’d be pretty skeptical. If you didn’t know about the metamorphosis of insects, you might be even more skeptical if someone claimed a sluglike caterpillar had any connection whatsoever to the dainty, almost lighter-than-air monarch butterfly.

Maybe a little less dramatic is the transformation of a flounder fry, which starts out life as a tiny, but normal looking fish larvae before it turns into a flatfish. This involves a dramatic loss of symmetry, and the migration of an eye from one side of the head to the other. Pretty alien-ish. This video of a vertical flounder larvae turning into a flatfish shows the process. It was done by Dr. Alexander Schreiber, who studies vertebrate metamorphosis at St. Lawrence University.

There are also insects that can pull off the trick of pretending to be a creature other than what they are. For example, there are beetles, wasps, and others who camouflage themselves, visually and chemically, to infiltrate ant colonies. They even make the same sounds the ants do. They do it so well, the ants feed them and take care of them so the aliens can grow up and lay eggs and have even more alien imitators. And the ants never recognize they are being preyed on that way. Very sci-fi creepy.

All of these examples are fascinating, and an actual part of life here on Earth. But the transformations I mentioned aren’t really quite what we’re looking for. For one thing, they’re all uni-directional. Once a tadpole turns into a toad, it can’t revert to a tadpole. Same for the caterpillar and the flounder fry. And the creepy ant pretenders are fairly limited. Generally they can only imitate a single species and they’re stuck doing it for life.

But in any event, your question wasn’t really, “Does such a thing exist?” It was “Can it evolve?” Knowing what we know about evolution and natural selection on earth, could an animal (or a plant, I suppose) evolve the ability to imitate multiple species, and change back and forth at will?

It turns out that one animal actually does have those abilities, maybe not quite like a science fiction shape-shifter, but enough that, with another billion years of evolution, who knows?

I’m talking about the mimic octopus, Thaumoctopus mimicus, which is believed to have at least 15 targets in the repertoire of animals it can shape-shift into. To see a mimic octopus imitate a poisonous flounder or venomous lionfish or sea snake is impressive. Not quite at the level of a sci-fi or fantasy novel shape-shifter, but it successfully fools a lot of other animals, both predators and prey. It can change into these other animals repeatedly and reversibly.

It is the closest thing to a shape-shifter on earth. And who knows? Given another billion years of evolution, if there is an advantage to even more accurate mimicry, the mimic octopus might become better and better at its tricks until it truly qualifies as a shape-shifter.

So Alexander, if you’re wondering if there is a shape-shifter already on earth, I think the closest we have is the mimic octopus. If you’re wondering if something even more impressive could someday evolve, I guess I don’t see why not.