An intra- and interspecific study of body size and autotomy as a defense in Orthoptera

Abstract

Autotomy, the ‘voluntary’ shedding of a limb or other body part, is a highly effective escape mechanism to avoid predation or other forms of entrapment. Autotomy, however, comes with costs to locomotion, reproductive behavior, regeneration etc. It has been suggested that increasing body size and ‘robustness’ may allow for less reliance on this extreme form of predator defense, but this theory has never been tested. Here we present behavioral observations (‘willingness’ or time taken to lose an entrapped limb) of Orthoptera of a range of body size and mass. These data strongly suggest that body size and mass may be an important determinant of the use of autotomy as an escape mechanism within the Order, possibly due to the effects of body size upon the efficacy of autotomy, as well as other defense mechanisms. An ontogenetic study for Gryllus bimaculatus, however, shows no clear trend in willingness to autotomize a limb with body mass, suggesting that this defense tactic may be less affected by body size per se, but rather by the tactics developed by each individual species.