Chemical recognition of kingsnakes by crotalines: effects of size on the ophiophage defensive response.

Abstract

When confronted by an ophiophagous (snake-eating) kingsnake, venomous snakes of the subfamily Crotalinae exhibit a suite of defensive responses including head hiding, thrashing, and an unusual response termed 'body bridging'. Other responses observed, such as biting and 'freezing', are more general in nature and can occur in a variety of contexts. Various crotalines of differing sizes were tested for their responses to kingsnakes (Lampropeltis getulus). Responses of individuals were recorded for up to 18 months. The results indicate that, if habituation can be overcome by periodically allowing a kingsnake to confront but not harm the crotaline, the response is dependent on the size of the crotaline, in that smaller specimens (< 0.9 m) respond readily, while larger snakes (> 1.0 m) tend not to respond. The size of the kingsnake apparently does not have an effect on the crotaline response. These data appear to resolve apparent conflicts in the literature regarding whether certain species respond to ophidian ophiophages. In addition, hexane extracts of kingsnake skin were fractionated using an alumina column. The various fractions obtained were tested to determine which elicited the defensive response. Activity was found only in the most non-polar fraction. Preliminary analysis by gas chromatography/mass spectrometry indicated that this fraction contained straight and branched, saturated and polyunsaturated long-chain hydrocarbons.