Coiling chirality? Wild eastern diamondback rattlesnakes (Crotalus adamanteus) do not exhibit clear lateralized coiling behaviour.

Abstract

Behavioural lateralization has been recorded in various groups, from lower vertebrates to humans. Handedness, or the preferred use of one hand over the other, as observed in humans, is thought to be related to brain structure and function. Snakes have been recorded to potentially display such sided behaviours. The asymmetrical internal anatomy of snakes may provide a basis for coiling handedness in the form of clockwise versus anti-clockwise coiling to protect vital organs or provide an advantageous strike to capture prey. The few studies on behavioural lateralization in snakes have documented inconsistent evidence to accurately determine whether coiling direction biases exist. However, these studies either failed to include repeated individuals or were conducted in aseptic environments, producing results that may not reflect natural conditions. To determine whether coil position bias exists amongst wild individuals, we studied eastern diamondback rattlesnakes (Crotalus adamanteus) at two sampling sites. We found no clear bias for coiling direction across populations or individuals, though sex-biased differences in directionality were identified. We found that lateralized coiling is not found in all snakes, and the genetic and ecological significance of such polymorphism, if any, warrants further investigation.