Examples of the three different head movements which were classified. First clip: straight down movement. A harbour seal approaches the active nozzle from the left, the breathing current is directed against its swimming direction, to the left (note the orientation of the nozzle below the mesh-grid). The seal moves straight toward the nozzle. Second clip: U-turn. A harbour seal approaches the active nozzle from the left, the breathing current is directed to the right. The seal passes the nozzle, then turns around. Third clip: correction. The harbour seal performs a U-turn, but suboptimally, and corrects its position to station at the nozzle.