News That Stays News

“I’m a snake! I’m a snake!” June 23, 2014

One thing that many humans, including biologists, find fascinating about caterpillars is how many of them look like other organisms or objects. There are caterpillars that people think look like sticks, leaves, flowers, bird droppings, moss, and snakes. Of course, humans are also the animals that invented Rorschach tests, so it’s an open question whether these caterpillars also fool animals with less imagination or less reliance on color vision.

Consider some caterpillars that have “eyes” and “faces” and might be trying to pass as some sort of snake:

Caterpillar “faces” from Janzen, D. H., W. Hallwachs, and J. M. Burns. 2010. A tropical horde of counterfeit predator eyes. PNAS 107:11659-11665.

I find some of these caterpillars more convincing than others, although the authors argue that a caterpillar-hunting bird that sees the “eyes” of something that might be a predator and sticks around to figure out if it really is a predator is probably not going to survive. After all, the bird only has to be wrong once.

But there are some caterpillars that are fairly convincing snakes. (Or snake heads—caterpillars just aren’t long enough to be whole snakes.) This is one of them, although as far as I’m aware, it doesn’t look like a particular snake:

Papilio astyalus pallas (Papillionidae — the swallowtail butterfly family)

One reason it’s so convincing is because whenever someone bothers it, it does this:

All that’s missing is a hiss.