Hydrodynamic and Kinematic Coordination in Aquatic Jumping

Rapid water escape maneuvers by aquatic organisms take significant energy and dexterity. Fish and other aquatic jumpers produce thrust in manners compatible with the transition from one fluid media to the next, accounting for the drastic drop in fluid density (and thus force-producing ability) between water and air, and, surface tension, depending on the organism size. Organisms ranging in size from large marine mammals and sharks to small copepods have developed aquatic jumping strategies compatible with their size and survival goals (e.g., prey capture, escape, mating or migration). Jumping for food, and especially a moving feast, requires higher precision than jumping for migration or escape. This talk will present our results with 3D light field particle imaging velocimetry (LFPIV), that lead to insights on the coordination of body and fin motions as well as thrust production capabilities of archer fish. The archer fish, Toxotes microlepis, are well known for generating precisely aimed jets of water from their mouths to capture prey, like an archer’s arrow. These fish are also adept at jumping to catch their prey, up to 2.5 body lengths out of the water. Their systematic and controlled fin and body motions are coordinated to produce the requisite energy needed to reach the desired jump height. Our 3D imaging results indicate a strong agreement between the cumulative effects of multiple propulsive motions and the instantaneous ballistic velocity of the fish. This agreement suggests that fin use may provide compensation for variations in individual kinematic events and in the aiming posture assumed prior to jumping. Our results highlight how interactions between tailbeats and other fins help the archer fish reach necessary prey heights in spatially- and visually-constrained environments. Synergistic multi-propulsor relationships identified from fish swimming investigations could be paradigm-shifting for the design of bioinspired multiphase vehicles.