Do lingual behaviors and locomotion by two gekkotan lizards after experimental loss of bitten prey indicate chemosensory search?

Abstract

Abstract Poststrike elevation in tongue-flicking rate (PETF) and strike-induced chemosensory searching (SICS) were assessed experimentally in two species of gekkonoid lizards belonging to families differing in foraging mode. PETF is an increase in rate of lingual protrusions after a prey item has been bitten and escapes or is removed from the mouth of a squamate reptile, whereas SICS is PETF combined with locomotory searching behavior. Eublepharis mucularius, the leopard gecko, is an actively, albeit slowly, foraging eublepharid. This species exhibited PETF for a duration of about five minutes based on total lingual protrusions. Labial-licks were initially much more frequent than tongue-flicks. A substantial increase in movement occurred during minutes 5-8, hinting that SICS might be present, but was not quite significant. SICS is likely present, as in other actively foraging lizards, but was not conclusively demonstrated. Handling the lizards induced increased locomotion in both the experimental condition and a control condition, presumably accounting for the apparent delay in onset of increased movement. The tokay gecko, Gekko gecko, a gekkonid ambush forager, performed no tongue-flicks, but exhibited PETF based on labial-licks during the first minute. SICS was absent. These findings support the hypothesis that SICS is absent in ambush foraging lizards, which do not use the lingual-vomeronasal system to search for prey. They are suggestive, but equivocal regarding the hypothesis that SICS is present in actively foraging lizards that exhibit lingually mediated prey chemical discrimination. The finding of PETF in G. gecko suggests that this species and several iguanians previously found to increase rates of labial-licking after biting prey may be able to detect prey chemicals.