Meeting Abstract
The evolutionary innovations that allow snakes to swallow large prey whole provide a model system for testing how anatomy constrains what predators eat. Several of the specializations in the dentition and cranial anatomy that facilitate snagging prey and swallowing large meals whole, however, seem maladaptive for functions such as taking bites or consuming hard-bodied prey. In this study, for a clade of three species of homalopsid snakes with the unusual diet of decapod crustaceans, we quantified maximal gape, prey size, and feeding behavior. Fordonia leucobalia eats hard-shelled crabs and had maximal gape similar to a piscivorous relative (Cerberus schneiderii). Gerarda prevostiana and Cantoria violacea eat freshly molted crabs and snapping shrimps, respectively, and their maximal gapes were significantly smaller than those of both F. leucobalia and C. schneiderii. The rank order of species from smallest to largest relative sizes of prey consumed in nature was F. leucobalia, C. violacea and G. prevostiana. Unusual specialized feeding behaviors included: 1) a closed-mouth strike and using the chin to initially pin down the crabs (F. leucobalia), 2) breaking off the crab legs (F. leucobalia, G. prevostiana), and 3) ripping apart the crab carapace aided by coils of the body (G. prevostiana). Behavioral innovations and choice of prey allowed G. prevostiana to readily consume crabs 2-4x larger than their maximal gape area, and they had prey handling times approximately 9x faster than those of F. leucobalia consuming prey of similar relative size. This is a striking example of how the evolution of specialized behaviors can improve performance and circumvent the anatomical constraints on prey size.
