The lateral line system of fish as a ``hydrodynamic antenna''

The lateral line of fish is a specialized flow detection system comprised of pressure- and shear-responsive sensors distributed over the body surface. Here, we explore how the arrangement of these sensors is related to the hydrodynamic information contained in flows. Using a cast model of a rainbow trout placed in a water tunnel, we devise ways to mimic the flows encountered by swimming fish while measuring the near-body flow field. Comparing our results to anatomical studies indicates that the lateral line sensors are well positioned to detect temporal and spatial changes in flow signals. These findings support a view of the lateral line as a ``hydrodynamic antenna'' that allows sophisticated behaviors such as rheotaxis and prey detection and tracking.