Marine turtle reception of bone-conducted sound.

An individual each of the marine turtles, Caretta caretta and Lepidochelys kempi, were stimulated with audiofrequencies delivered directly to the skull. Startle responses were observed to underwater stimuli of .25 and .5 kc/s. Neural responses to underwater bone-conducted (bc) sound were recorded in another aquatic form, the snapping turtle, Chelydridae serpentina. The morphology of the neural response suggested the involvement of the auditory system in bc responsivity. Bc hearing appears to be a reception mechanism for marine turtles with the skull and shell acting as receiving surfaces. Turtles are capable of receiving the low-frequency spectrum of the natal beach, which may serve as one of the cues in nesting returns.