Neurobiology of the Fish Lateral Line: Adaptations for the Detection of Hydrodynamic Stimuli in Running Water

Abstract

All fishes possess a lateral line system, which serves as a receptor for hydrodynamic stimuli such as those generated by conspecifics, predators or prey. The lateral line is comprised of numerous individual sensory units, the neuromasts, which can occur freestanding on the surface of the skin or embedded in subepidermal canals. The morphological design of the peripheral lateral line can be quite different in different fish species and is thought to represent an adaptation to the hydrodynamic conditions that prevail in the habitat of a given species. However, despite gross morphological differences, the general physiology of the peripheral lateral line appears to be quite similar in different fish species at least when the system is studied under still water conditions. In contrast to the peripheral lateral line that has been studied extensively, much less is known about the processing of hydrodynamic information by lateral line neurons in the fish brain. In addition, not much is known about the processing of naturally occurring hydrodynamic stimuli. In order to understand how the lateral line functions under more natural stimulus conditions, complex water motions generated by moving sources have been used as lateral line stimuli and the system has been studied under running water conditions. This chapter summarizes the main result from these studies, which have, for the first time, revealed a clear form-function relationship for the lateral line system.