YOUNG, B.A.; MORAIN, M.: Prey Localization by Vibration Detection in Saharan Sand Vipers (Cerastes)

Snakes of the genus Cerastes are ambush predators which launch strikes while partially, or fully, buried in sand. Our observations indicated that the mouth and snout are typically covered in sand, and tongue flicks are rarely observed prior to predatory strikes. High-speed digital videography was used to record a series of strikes directed at small, unrestrained laboratory mice. Using NIH Image the strike distance, terminal strike velocity, and strike angle were quantified. The snakes were anesthetized and the olfactory and vomeronasal nerves bilaterally severed. A second series of strikes, recorded following recovery and at the same size targets, revealed no significant changes in predatory behavior or quantified features of the strike. The eyes of each denervated specimen were then occluded using surgical tape and non-toxic black paint. The denervated, functionally blind, specimens exhibited changes in predatory behavior, significant decreases in strike distance and strike angle, and reduced accuracy of the strike. Nevertheless these denervated, functionally blind, specimens were still able to capture free-ranging prey. A second series of trials were performed on the denervated, functionally blind, specimens using Styrofoam balls as targets. These targets were either isothermic (heated on the sand substrate) or heated to the body temperature of a small mammal using a radiant heater. Tapping these artificial targets on the sand evoked a marked response from the specimens, including strikes in 1/4 of the trials. These results represent the first experimental evidence that snakes can use vibration-detection for behaviors as ecologically significant as prey capture.