Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 31, Number 11;   November, 2004

Really Sinister

But a left-handed snake? Well, yes, when snakes are at rest, they coil their bodies, and that puts one side or the other on the inside of the coil. According to Eric D. Roth, a herpetologist at the University of Oklahoma in Norman, if an individual snake or a species coils one way or the other in a reasonably consistent way, it makes sense to call the behavior "handedness."

Roth recently spent six months repeatedly noting the coiling configuration of twenty adult cottonmouths, a venomous species native to the southeastern United States. Sixteen of the cottonmouths coiled more often with the left side of the body on the inside of the coil. Roth considered the effect strong enough to regard the population as "left-handed." Among the sixteen lefties, three were southpaws at the individual level; they coiled to the left twice as often as they coiled to the right -- too marked a tendency to be caused by chance alone.

Does the frequency of handedness -- or, more generally, "behavioral lateralization" -- in lower vertebrates suggest that the animal brain became lateralized early in vertebrate evolution? It's too soon to tell.

But it is safe to say that the idea of a left-handed snake isn't just a put-on.

("Handedness in snakes? Lateralization of coiling behavior in a cottonmouth, Agkistrodon piscivorus leucostoma, population," Animal Behaviour 66:337 -41, August 2003)