An Eyeful of Natural Selection
Posted by Richard Conniff on October 1, 2012
(Photo selection from Rainforest Journeys)
You are looking at the hind end [see correction below] of various rainforest caterpillars. But if you thought for just a moment that you were looking at snakes or lizards, well, so do a lot of predators. And that’s the point.
These false eye spots give defenseless caterpillars a moment of protection, startling birds, for instance, into sudden retreat. The caterpillars that don’t have that startle effect get eaten up. Thus natural selection has made the trait widespread in the caterpillar world.
Baron Patrick de Koenigswarter said
While reluctant to contradict a world renown nature expert (for whose works btw am full of admiration) like yourself, in my personal experience, the eye-spots on Hawk-moth larvae are almost always located on the front (head side), not the rear end of these extraordinary creatures, which scare off predators by rearing up (or hanging down and swaying) to best show off the eyespots and to startle their foes (sometimes with an audible snakelike hiss added on as well!)
Richard Conniff said
With apologies, Patrick, I’m a writer about nature rather than a true nature expert. But you are correct. I consulted my caterpillar guru, Dave Wagner at the University of Connecticut, who replied:
“I am siding with the Baron. If you had some sort of title I might feel differently.
In the ten images, I think that I can recognize nine to family:
6 swallowtails
3 sphingids
In these nine the eyespots are on the head end–all on the thorax, by the way (none actually on the head–the true head is concealed and out of harm’s way).
There is a spectacular example of a squeaking sphinx in Connecticut with its eyespot on the rear, Sphecodina abbottii (Abbott’s Sphinx), which may well have “colored” your view.”