DEBAN, Stephen M.; O’REILLY, James C.; DICKE, Ursula; VAN LEEUWEN, Johan; Univ. of Utah, Salt Lake City; Univ. of Miami, Coral Gables; Univ. of Bremen, Germany; Wageningen University, Netherlands: Extremely high-power tongue projection in plethodontid salamanders

Plethodontid salamanders can project the tongue very rapidly for long distances. In many species, the tongue and its supporting skeleton can be projected ballistically from the mouth, evacuating the subarcualis rectus (i.e., projector) muscles entirely and reaching the prey in a few milliseconds. Tongue projection dynamics were examined in three genera of plethodontids from two clades which are capable of ballistic tongue projection, Bolitoglossa, Hydromantes, and Eurycea. Salamanders were videotaped at 1000-2000 Hz projecting their tongues at prey, and videos were analyzed kinematically to determine the instantaneous position of the tongue relative to the salamander. Instantaneous velocity, acceleration, and mass-specific power were calculated from smoothed position data. Instantaneous mass-specific power output of the subarcualis rectus muscles was calculated using the ratio of mass of the projected tongue plus skeleton to the mass of the muscles, measured in preserved specimens. All three genera produce extremely high mass-specific power output during the first half of tongue projection, when velocity and acceleration are both high (3.6 ± 0.2 m/s and 1875 ± 151 m/s/s). Bolitoglossa exhibited the greatest peak instantaneous power, at 7444 ± 875 W/kg (18307 W/kg maximum), followed by Eurycea at 4016 ± 640 W/kg (9806 W/kg maximum) and Hydromantes at 1989 ± 359 W/kg (4943 W/kg maximum). Peak power output is positively correlated with tongue projection distance, which is consistent with a ballistic model of tongue projection. Power output of the subarcualis rectus muscles in all three genera vastly exceeds mass-specific power output for other vertebrate muscles that have been studied.