Meeting Abstract
Salamanders often use tongue projection to feed on land. Most plethodontid salamanders possess a high-powered, thermally robust, ballistic tongue-projection mechanism in which collagen aponeuroses within the projector muscles store elastic potential energy. Elastic storage allows projection performance to exceed that possible with muscle alone. Chioglossa lusitanica has a feeding morphology that is convergent with that of plethodontids and divergent from that of other salamanders in the Salamandridae. Tongue projection is also more elaborate in this species compared to other salamanders. During tongue projection elongate radials rotate about the projecting basibranchial, carrying a sticky tongue pad towards the prey. Using high-speed videography, kinematics, and inverse dynamic analyses, we examined this elaborate tongue projection at a range of temperatures to determine if elastic-recoil mechanisms similar to those in plethodontids could also be used in this distantly related taxon. During both tongue projection and radial rotation, Chioglossa showed evidence of an elastic mechanism. Power outputs for tongue projection exceeded 4000 W/kg, while radial rotation often reached over 2000 W/kg. Although power outputs of over 1000 W/kg were still observed over a 10-degree temperature difference, there were decreases in both components of projection performance as temperature decreased. Histological sections of the projector muscles showed the presence of collagen aponeuroses similar to those seen in plethodontid salamanders, which may be the location of elastic energy storage. These results suggest convergent evolution of elastic recoil in Chioglossa and plethodontids used for high-powered tongue projection.
