PHYSIOLOGY OF ORIGINAL AND REGENERATED LIZARD TAILS

Many lizards autotomize their tails during an encounter with a predator. Tails thrash following autotomy, thus distracting the predator and increasing the probability of escape. Regeneration of the tail occurs rapidly in many species of lizards. We investigated several aspects of the physiology of original and regenerated tails of the gecko Hemidactylus mabouia. Thrashing durations of original and regenerated tails after autotomy were similar, but original tails accumulated significantly more lactate per gram tissue than did regenerated tails. The reduction in lactate concentration paralleled a reduction in protein concentration in regenerated tails suggesting that lower protein concentrations in regenerated tails contributed to lower lactate concentrations. Lactate dehydrogenase (LDH) activity was not significantly different in original and regenerated tails, suggesting that LDH was not responsible for the observed difference in lactate concentrations. Histochemical and immunochemical analyses revealed that the number, size, and type of muscle fibers were not different in original and regenerated tails. Caudal fibers were mainly of the fast, glycolytic type, which presumably support high anaerobic activity of the tail following autotomy.