Discrimination of sounds based on the phase difference between particle motion and acoustic pressure in the shark Chiloscyllium griseum.

The reported psychophysical study indicates that a shark not only detects particle motion in a sound field (f = 84 Hz) but moreover shows a sensitivity to acoustic pressure. These results are remarkable because sharks lack a gas bladder that can act as a pressure-to-displacement transformer enabling the hair cells in the labyrinths to respond to acoustic pressure indirectly. The probable significance of the observed phenomena for acoustic localization in fish is discussed and a possible pressure-to-displacement transformer in shark is proposed.