Meeting Abstract

36.2  Friday, Jan. 4  It�s in the way that you use it: how activation patterns affect anuran feeding behavior ZEPNEWSKI, E.D*; CARRENO, C.A.; LAPPIN, A.K.; NISHIKAWA, K.C.; Northern Arizona University; Duke University; California Polytechnic State University; Northern Arizona University eric.zepnewski@nau.edu

Most frogs and toads capture prey by protracting their tongues. More than 90% of the power for this movement is generated by a single pair of jaw opening (depressor) muscles. In species of Bufo, the depressor muscles are pre-loaded to achieve the relatively high forces necessary for ballistic tongue protraction. When the depressor muscles are pre-loaded, elastic energy is stored and then recovered during mouth opening. As such, the spring properties of the depressor muscles are thought to play an important role. In comparison, Ceratophrys cranwelli exhibits non-ballistic tongue protraction. Simultaneous EMG and high-speed video recordings show that the depressor muscles are not pre-loaded prior to tongue protraction. In situ muscle lever experiments in Ceratophrys demonstrated that active depressor muscle stiffness during shortening resembled stiffness values of Bufo when they were loaded similarly. Thus, behavioral differences may be explained by different morphologies. Morphological measurements showed differences in mechanical advantage between species. These results suggest that muscle is an adaptable tissue that, by virtue of common intrinsic elastic properties, may exhibit extremely different behaviors under varying conditions of activation, load, and mechanical advantage. Supported by NSF IOS-0623791, IOS-0732949, NIH R25-GM56931, the TRIF Fund for Biotechnology and Science Foundation Arizona.