UBC Theses and Dissertations
Orientation of fishes to low frequency sound sources and the role of the lateral line system Russell, Ian John
A theoretical analysis of the acoustic field around a sound source suggested that fish would be able to locate a sound source by detecting the associated near field displacements with their lateral line system. Blinded goldfish and Mexican blind cave characins were able to locate both stationary objects and sound sources. The lateral line system was implicated as the directionally sensitive organs involved. Blind cave fish were able to locate both stationary objects and a sound source against a background noise. The existence of a noise suppressing mechanism to the lateral line organs was suggested. An efferent nervous supply was shown to innervate anterior lateral line organs of goldfish, and the inhibitory nature of the efferent nerves was demonstrated. The efferent nerves were found to be insensitive to the stimulation of acoustically sensitive organs on the fish, but responded to changing states of muscular activity in the fish. Swimming goldfish changed hydrodynamically during respiration from bluff bodies, when their mouths were shut, to streamlined bodies, when their mouths were open. This change in configuration lead to the proposal that the anterior lateral line organs function both as velocity detectors and near field displacement detectors. A central location was suggested for a neuro-physiological noise attenuating system to the lateral line system, and the efferent nerves innervating the lateral line organs were suggested to form part of a mechanism reflexively controlling swimming velocity.
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