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

Behavior can be regarded as a result of various processes ofdecision 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 withrespect to the feeding behavior of snakes. The hierarchy ofthe sensory information in various phases of the feeding behaviordiffers between snakes possessing heat receptors (e.g., speciesof the Crotalinae and Pythoninae) and those without (e.g., speciesof the Viperinae and Colubrinae). Probably depending on theinfluence of ecological demands, visual or chemical cues arethe main information in the behavioral phases before the strikeHowever, in situations with little visual input, e.g., in darkness,rodents' burrows, etc., hunting behavior is guided in the firstplace by radiation of warm objects in Crotalus, Python and Trimeresurusflavoviridis, and by substrate vibrations in Vipera aspis, Pituophismelanoleucus and Boa constrictor. I suggest that in the sensoryhierarchy, heat information functionally replaces the mechanicalinformation which is utilized by snakes without pit organs.Poststrike behavior on the other hand is mainly guided by chemicalcues in all snakes.