Duration of poststrike elevation in tongue-flicking rate in the savannah monitor lizard,Varanus exanthematicus

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Abstract
The duration of poststrike elevation in tongue-flicking (PETF) in the savannah monitor, Varanus exanthematicus, is experimentally estimated to be at least 25 min, with some residual increase persisting for at least 30 min. This is by far the most prolonged PETF yet observed in a lizard, as predicted from the active foraging on mobile prey and the chemosensory specializations of the varanid tongue. PETF is shorter than in rattlesnakes, presumably because prolonged search is more likely to be successful when the prey has been envenomated. Strike-induced chemosensory searching, which consists of both PETF and searching movements, appears to be of shorter dutation than PETF because searching movements do not last as long as PETF. Individual lizards differ markedly in the duration of tongue-flicking and the degree of increase in tongueflicking attributable to biting prey. Individuals tongue-flick at their own highest rates in the first minutes after stimulus presentation, then show a decline, often to zero. Some individuals resume tongue-flicking, sometimes at high rates, after having stopped for one to several minutes. Such behavior may aid in relocation of escaped prey that has reemerged after the initial chemosensory search has failed or in location of similar prey likely to be in the vicinity if patchily distributed. Methods of analyzing data on duration of PETF are considered.