Thermal Sensitivity as a Specialization for Prey Capture and Feeding in Snakes

Abstract

Behavior can be regarded as a result of various processes of decision based on the information provided by the sensory organs. In this review the role of the so-called additional heat sense, next to vision, smell and mechanoreception is discussed with respect to the feeding behavior of snakes. The hierarchy of the sensory information in various phases of the feeding behavior differs between snakes possessing heat receptors (e.g., species of the Crotalinae and Pythoninae) and those without (e.g., species of the Viperinae and Colubrinae). Probably depending on the influence of ecological demands, visual or chemical cues are the main information in the behavioral phases before the strike However, in situations with little visual input, e.g., in darkness, rodents' burrows, etc., hunting behavior is guided in the first place by radiation of warm objects in Crotalus, Python and Trimeresurus flavoviridis, and by substrate vibrations in Vipera aspis, Pituophis melanoleucus and Boa constrictor. I suggest that in the sensory hierarchy, heat information functionally replaces the mechanical information which is utilized by snakes without pit organs. Poststrike behavior on the other hand is mainly guided by chemical cues in all snakes.