Go Against the Flow The sophisticated sensory system that allows zebrafish to navigate the current The cover shows the larva of a zebrafish (Danio rerio). Shown in red is a series of hair cells known as the lateral line. These hair cells are used first to detect tiny vortices in the water flow and then to track how these vortices evolve thereby revealing the direction of the current. In the wild, this would enable the fish to navigate in environments that lack visual cues.