hemosensory 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 lost food. In contrast, previously studied iguanian families other than Iguanidae lack lingually mediated prey chemical discrimination (PCD) and do not exhibit lingually mediated chemosensory searching behavior for bitten prey that has escaped or been lost (SICS = strikeinduced chemosensory searching). In the present study, experimental tests showed that PCD and SICS are absent in Crotuphytus collaris, a member of the previously unstudied family of iguanian ambush foragers, Crotaphytidae. Available data suggest that in active foragers natural selection favors use of chemical cues to locate hidden prey, whereas in ambush foragers natural selection favors immobility to avoid detection by predators and SICS precludes simultaneous ambush. In most families the states of PCD and SICS are retained from the ancestors, but when foraging mode shifts, a change in chemosensory behavior appears to be induced. A proposal is made for a research program involving herpetologists at zoos. @ 1996 &'iley-Liss, Inc.