Meeting Abstract
Salamanders use the hyobranchial apparatus and its associated musculature for tongue projection on land and for suction feeding in water. Hyobranchial apparatus composition and morphology vary across species and different morphologies are better suited for feeding in aquatic versus terrestrial environments. We hypothesized that differences in hyobranchial morphology result in functional trade-offs in feeding performance. We predicted that semi-aquatic and aquatic salamandrids with hyobranchial morphology suited for aquatic feeding will have lower performance, in terms of tongue-projection distance, velocity, acceleration and power, compared to terrestrial salamandrids when feeding in a terrestrial environment. We found that semi-aquatic and aquatic newts had lower tongue-projection performance when compared to the terrestrial salamanders Chioglossa lusitanica and Salamandra salamandra. The fully aquatic newt, Paramesotriton labiatus, has a robust, heavily mineralized hyobranchial apparatus and was unable to project its tongue during terrestrial feeding. Conversely, terrestrial species have slender, cartilaginous hyobranchial apparatus and enlarged tongue pads that coincided with greater tongue projection distance, velocity, acceleration, and power. Chioglossa exhibited extreme tongue-projection performance, similar to that seen in elastically projecting plethodontid salamanders; muscle-mass-specific power of tongue projection exceeded 2200 W/kg, more than 350 times that of the next highest performer, Salamandra, which reached 6.3 W/kg. These findings reveal that two fully terrestrial salamandrids have morphological specializations that yield greater tongue-projection performance compared to species that naturally feed in both aquatic and terrestrial environments.
