Role of sea lion head in swimming and jumping

Sea lions are notably skillful swimmers. They use their fore flippers to generate thrust in a unique form of drag-based propulsion known as “clapping” and as hydrofoil-like structures to generate lift. Sea lions can complete a 180 degree turn in less than one body length, and they are known to rapidly exit and enter the surface of the water in a behavior known as “porpoising.” During these behaviors (swimming, turning, and porpoising) the effects of the head of these animals is unknown. Using 3D models of a sea lion head mounted in a wind tunnel, we examine the hydrodynamic forces generated by the sea lion head at different angles of attack. Separately, we use a drop cage and high-speed camera to study a sea lion head’s entry behavior at varying angles. These findings will help us understand how the sea lion head contributes to its behaviors, and inform future work in sea-lion-inspired aquatic vehicles.