SMITH, T.L.; KARDONG, K.V.: Poststrike chemosensory trailing in rattlesnakes: Kinematics and function of tongue-flicking

Rattlesnakes in the wild usually strike, envenomate, and release rodent prey. Released rodent prey dash off from the snake some distance before succumbing to the immobilizing, and eventually, lethal effects of the venom, leaving the snake with the task of recovering the released rodent. Rattlesnakes are very good at recovery and can distinguish the trail of the outgoing struck rodent from a trail made by the same animal incoming, prestrike. Critical to this acute detection of prey scent is the gathering of chemical cues specific to the envenomated prey, a role performed by the tongue. Therefore we examined the deployment and function of tongue-flicking during the poststrike phase of predation. We sought to answer the following questions: 1. When during poststrike trailing is the tongue used. 2. How is the tongue used under these conditions. 3. Where in the air column and on the substrate is the tongue sampling odors; and 4. What is being sampled. Qualitative and quantitative analysis, including kinematic analysis, indicate that the manner of tongue-flicking is unique to different stages of the poststrike predatory behavior and this might correlate with function, exploratory versus trailing tongue-flicks, or with the nature of the chemical cue being sampled, for example volatile versus nonvolatile. Consequently, it appears that the positioning of tongue-flicks above and along the poststrike scent trail and the tongue’s action contribute to effective detection of the unique chemical profile of the envenomated prey.