Losing stability: tail loss and jumping in the arboreal lizardAnolis carolinensis

Abstract

Voluntary loss of an appendage, or autotomy, is a remarkable behavior that is widespread among many arthropods and lower vertebrates. Its immediate benefit, generally escape from a predator, is balanced by various costs, including impaired locomotor performance, reproductive success and long-term survival. Among vertebrates, autotomy is most widespread in lizards, in which tail loss has been documented in close to 100 species. Despite numerous studies of the potential costs of tail autotomy in lizards, none have focused on the importance of the tail in jumping. Using high-speed video we recorded jumps from six lizards (Anolis carolinensis) both before and after removing 80% of the tail to test the hypothesis that tail loss has a significant effect on jumping kinematics. Several key performance metrics, including jump distance and takeoff velocity, were not affected by experimental tail removal, averaging 21 cm and 124 cm s(-1), respectively, in both tailed and tailless lizards. However, in-air stability during jumping was greatly compromised after tail removal. Lizards without tails rotated posteriorly more than 30 deg., on average, between takeoff and landing (and sometimes more than 90 deg.) compared with an average of 5 deg. of rotation in lizards with intact tails. Such exaggerated posterior rotation prevents coordinated landing, which is critical for animals that spend much of their time jumping to and from small branches. This work augments recent experiments demonstrating the importance of the tail as a mid-air stabilizer during falling in geckos, and emphasizes new and severe functional costs associated with tail autotomy in arboreal lizards.