The Auditory Periphery in Fishes

Abstract

Fossil evidence shows that an inner ear is found in the most primitive of jawless vertebrates (Stensiö 1927; Jarvick 1980; Long 1995). It may never be known whether these vertebrates actually were able to “hear” or whether the earliest ear may have been only a vestibular organ for the detection of angular and linear accelerations of the head. However, it is not hard to imagine that such a system could have ultimately evolved into a system for detection of somewhat higher frequency sounds during early vertebrate evolution (Van Bergeijk 1967; Poper and Fay 1997). Although some might argue that sound detection would not have evolved until fish, or predators, started to make sounds, this may not be a valid argument. In fact, it is very likely that the earliest role, and still the most general role, for sound detection is to enable a fish to gain information about its environment from the environment’s acoustic signature (Popper and Fay 1993). Such a signature results from the ways a sound field produced by sources such as surface waves, wind, rain, and moving animals is scattered by things like the water surface, bottom, and other objects.