The mechanosensory lateral line system of the hypogean form of Astyanax fasciatus

The mechanosensory lateral line is a distributed, hair-cell based system wh ich detects the water flow regime at the surface of the fish. Superficial n euromasts densely scattered over the surface of some cave fish detect the p attern of flow over the surface of the body and are important in rheotactic behaviors and perhaps in the localization of small vibrating sources. Cana l neuromasts are very likely also involved in the detection of small plankt onic prey, but seem also to play an essential role in replacing vision as t he major sense by which blind cave-fish perceive their surroundings. The fl ow-field that exists around a gliding fish is perturbed by objects in the i mmediate vicinity, these perturbations are detected by the lateral line sys tem. In this way the fish can build up a 'picture' of its environment, a pr ocess that has been called active hydrodynamic imaging. None of the lateral line behaviors exhibited by blind cave fish are necessarily exclusive to t hese species, but there is some evidence that their lateral line capabiliti es are enhanced with respect to their sighted relatives.