Karman vortex street detection by the lateral line

Fish use the lateral line system for prey detection, predator avoidance, schooling behavior, intraspecific communication and spatial orientation. In addition the lateral line may be important for station holding and for the detection of the hydrodynamic trails (vortex streets) generated by swimming fish. We investigated the responses of anterior lateral line nerve fibers of goldfish, Carassius auratus, to unidirectional water flow (10 cm s(-1)) and to running water that contained a Karman vortex street. Compared to still water conditions, both unidirectional water flow and Karman vortex streets caused a similar increase in the discharge rate of anterior lateral line nerve fibers. If exposed to a Karman vortex street, the amplitude of spike train frequency spectra increased at the vortex shedding frequency. This increase was especially pronounced if the fish intercepted the edge of a Karman vortex street. Our data show that the vortex shedding frequency can be retrieved from the responses of anterior lateral line nerve fibers.