MULTIPLE FUNCTIONS OF EXTRAORAL LINGUAL BEHAVIOR IN IGUANIAN LIZARDS - PREY CAPTURE, GROOMING AND SWALLOWING, BUT NOT PREY DETECTION

Lingual chemosensory sampling allows many lizards to detect and later relocate prey after failed capture attempts. Although several families in the iguanian radiation do not discriminate prey chemicals prior to attack on prey, little is known about their responses to oral contact with prey chemicals during successful or failed predation attempts. Experimental tests of responses to swabs bearing surface chemicals from prey revealed no evidence of prey chemical discrimination in two species from different iguanian families. Neither of these nor a third species exhibited strike-induced chemosensory searching in experiments that readily elicit this behaviour in many other lizard taxa. None of the three species performed searching movements after ingesting prey. The form of lingual protrusion observed differed from that used by other lizards to detect prey. Instead of being directed to environmental substrates, the tongue was used to capture prey or lick the labial scales, or was protruded in a manner suggesting postural adjustments or cleaning subsequent to swallowing. Comparison of present and previous results suggests that use of lingually mediated prey chemical discrimination prior to attack and strike-induced chemosensory searching after attack may be coupled in carnivorous lizards, both being present or both absent. Available data suggest that lingual sampling to detect prey in pre- and post-attack settings occurs in actively foraging lizards, but not in ambush foragers, and that it typically occurs in both settings in scleroglossans, but not iguanians. Although iguanians do not use the tongue to detect prey chemicals before attack, lingual prehension of prey or labial-licking may have provided the contact with chemicals on environmental substrates that led to selection for tongue-flicking to detect prey chemicals or pheromones. © 1993 The Association for the Study of Animal Behaviour.