Detection of infrasound and linear acceleration in fishes

Fishes have an acute sensitivity to extremely low-frequency linear accelera tion, or infrasound, even down to below 1 Hz. The otolith organs are the se nsor!: system responsible for this ability The hydrodynamic noise generated by swimming fishes is mainly in the infrasound range, and may be important in courtship and predator interactions. Intense infrasound has a deterring effect on some species, and has a potential in acoustic barriers. We hypot hesize that the pattern of ambient infrasound in the oceans may be used for orientation in migratory fishes, and that pelagic fishes may detect change s in the surface wave pattern associated with altered water depth and dista nt land formations. We suggest that the acute sensitivity to linear acceler ation could be used for inertial guidance, and to detect the relative veloc ity of layered ocean currents. Sensitivity to infrasound may be a widesprea d ability among aquatic organisms, and has also been reported in cephalopod s and crustaceans.