Session B9: How Fish Use and Process Flow Information

Abstract: Fish use the mechanosensory lateral line and the acoustic system for the processing of hydrodynamic information. With their lateral line fish perceive the amplitude, direction and frequency content of water motions relative to their body and tail fin surface as well as local pressure gradients across their head and trunk. With the acoustic system fish detect the particle displacement component and the pressure amplitude of a sound wave. Both, the lateral line and acoustic system, play an important role in many fish behaviors, including schooling, predator avoidance, intraspecific communication and prey detection. With the acoustic system fish not only can discriminate multiple sound sources but in addition can determine the direction and distance to these sources. Rheophilic fish even use lateral line (and acoustic?) information to save energy while swimming in turbulent flow. The smallest sensory unit of the lateral line is the neuromast. The lateral line neuromasts occur freestanding on the surface of a fish or they are embedded in lateral line canals. Inner ear receptors relevant for the processing of sound information are the hair cells of the utricle, sacculus and lagena. Hydrodynamic stimuli are received and transduced into neuronal signals by the lateral line neuromasts and the inner ear receptors. Lateral line and acoustic information is conveyed by afferent nerve fibres to the fish’s brain and processed by higher order neurons in distinct nuclei. In my talk I will introduce the peripheral morphology of the lateral line and acoustic system of fish, describe behavioral and physiological work, thereby focusing on recent studies that have investigated how fish behave in unsteady flow, what kind of sensory information is provided by the flow and how fish use and process this information