CARRE-O, C.A.*; NISHIKAWA, K.C.: Does morphology correlate with prey capture kinematics in leptodactylid frogs?

Leptodactylid frogs exhibit diversity of the tongue and jaw mechanics during prey capture. Two mechanisms of prey capture have been seen in leptodactylids: inertial elongation and mechanical pulling. Phylogenetic analyses suggest that inertial elongation has evolved independently from mechanical pulling several times within leptodactylids. The goal of this study is to examine the evolution of feeding mechanisms in this diverse group of frogs. Feeding mechanisms of frogs can be categorized based on patterns of kinematics. The primary kinematic difference between inertial elongation and mechanical pulling is the movements of the tongue and jaw. During inertial elongation, the movements of the tongue and jaw are precisely coordinated, whereas in mechanical pulling, these movements are uncoupled. Leptodactylids that are considered to be inertial elongators tend to have short gape cycles (~11 ms), a high velocity of the lower jaw during mouth opening, and a great increase in the length of the tongue (180% of resting length). In contrast, leptodactylid frogs that are defined as mechanical pullers generally have longer gape cycles (~28 ms), slower velocity of the lower jaw, and a decrease in the length of the tongue during protraction (40% of resting length). Thus, we expect to find relative differences in the lever system of the jaw between inertial elongators and mechanical pullers. Inertial elongators should have proportionally shorter in-levers in order to maximize the speed of mouth opening, while mechanical pullers should have proportionally longer in-levers in order to maximize the force of mouth closing. The variability in kinematics and morphology among species of leptodactylids may reflect differences in the foraging ecology between species.