Meeting Abstract
Competition for food drives the evolution of specialized feeding morphology. Stomatopod crustaceans are often touted as having highly specialized feeding morphologies that are typically one of two forms: the more ancestral spear-like appendages used to ambush soft-bodied evasive prey (“spearers”) or hammer-like appendages that produce extremely high forces used both to break hard-shelled prey and to capture evasive prey (“smashers”). To evaluate associations between appendage type and feeding ecology, the diets of a smasher (Gonodactylus childi) and a sympatric spearer (Raoulserenea moorea) (size range: 21–27 mm) were compared. Stable isotope analysis and the Bayesian mixing model, MixSIAR, were used to estimate the proportional contributions of different prey to the diet for each species. Models were run with an experimentally-derived discrimination factor (DF; difference between predator and prey isotope values) as well as a DF calculated from the literature. Results from all models showed that both species had wide diets that included hard-shelled and soft-bodied prey, although in different proportions. The smasher consumed mostly hard-shelled prey (68–70%), and the spearer consumed mostly soft-bodied prey (62–73%). These similarly-sized species may produce similar kinematics, allowing them both to capture evasive prey and hammer hard-shelled prey, thereby broadening their diets. Yet, the spearer species is more adept at capturing evasive prey, indicating that small spearers are stronger competitors for soft-bodied prey. These findings suggest that a smasher’s ability to access hard prey reduced competition for soft prey, which may have conferred an important benefit favoring the evolution of the impressive smashing strike.
