PREY CHEMICAL-DISCRIMINATION AND STRIKE-INDUCED CHEMOSENSORY SEARCHING IN LIZARDS - THEIR ABSENCE IN A CROTAPHYTID-LIZARD (CROTAPHYTUS-COLLARIS) AND A PROPOSAL FOR RESEARCH IN ZOOS

Lizards in scleroglossan families of actively foraging carnivores and the herbivorous iguanids use the tongue to gather chemical samples to detect, identify, and locate food prior to attack, and to relocate los t food. In contrast, previously studied iguanian families other than I guanidae lack lingually mediated prey chemical discrimination (PCD) an d do not exhibit lingually mediated chemosensory searching behavior fo r bitten prey that has escaped or been lost (SICS = strike-induced che mosensory searching). In the present study, experimental tests showed that PCD and SICS are absent in Crotaphytus collaris, a member of the previously unstudied family of iguanian ambush foragers, Crotaphytidae . Available data suggest that in active foragers natural selection fav ors use of chemical cues to locate hidden prey, whereas in ambush fora gers natural selection favors immobility to avoid detection by predato rs and SICS precludes simultaneous ambush. In most families the states of PCD and SICS are retained from the ancestors, but when foraging mo de shifts, a change in chemosensory behavior appears to be induced. A proposal is made for a research program involving herpetologists at to es. (C) 1996 Wiley-Liss, Inc.