Energetic and physiological correlates of prey handling and ingestion in lizards and snakes

In this review, we summarize the energetic and physiological correlates of prey handling and ingestion in lizards and snakes. There were marked differ ences in the magnitude of aerobic metabolism during prey handling and inges tion between these two groups, although they show a similar pattern of vari ation as a function of relative prey mass. For lizards, the magnitude of ae robic metabolism during prey handling and ingestion also varied as a functi on of morphological specializations for a particular habitat, prey type, an d behavior. For snakes, interspecific differences in aerobic metabolism dur ing prey handling seem to be correlated with adaptations for prey capture ( venom injection vs. constriction). During ingestion by snakes, differences in aerobic metabolism might be due to differences in cranial morphology, al though allometric effects might be a potentially confounded effect. Anaerob ic metabolism is used for prey handling and ingestion, but its relative con tribution to total ATP production seems to be more pronounced in snakes tha n in lizards. The energetic costs of prey handling and ingestion are trivia l for both groups and cannot be used to predict patterns of prey-size selec tion. For lizards, it seems that morphological and ecological factors set t he constraints on prey handling and ingestion. For snakes, besides these tw o factors, the capacity of the cardio-respiratory system may also be an imp ortant factor constraining the capacity for prey handling and ingestion. (C ) 2001 Elsevier Science Inc. All rights reserved.