Examples of trials with and without head retraction in seal Filou. Clip1: a trial where the seal is blindfolded. No distinctive head movements at the nozzles (in the centers of the red circles) are performed until the seal finds the active nozzle (no. 8, upper left). Clip 2: a trial where the seal is not blindfolded. At the nozzles in the centers of the red circles, the seal briefly retracts its head to reduce the forward speed of the vibrissal array, while swimming speed is maintained.