Fish can sense subtle differences in water pressure and velocity using the lateral line, a collection of sense organs that run the length of their bodies. So far, most research into this capability has been limited to the sensing of simple oscillating objects. Jan-Moritz Franosch of the Technical University of Munich in Germany and his colleagues now show how fish detect more complex disturbances — the orientation of ring-shaped vortices left in the wake of other fishes.
The authors modelled the stimulus expected from a vortex ring passing a fish's lateral line and compared this with recorded neuronal responses from a fish fixed in place and subjected to passing vortices. The recordings fit the model's predictions. Information on the orientation of vortices should allow fish to track the movement of other animals — and perhaps a meal — the authors argue.