ALEXANDER, J.K.*; TYTELL, E.D.; Harvard University; Harvard University: Synchronization of respiration and locomotion in the bluegill sunfish Lepomis macrochirus

To determine if fish synchronize their locomotion and respiration, we filmed bluegill sunfish (Lepomis macrochirus) using high-speed video and calculated the time differences between locomotory and respiratory events. It is well known that many tetrapods, from lizards to humans, synchronize their respiration and locomotion in such a way as to improve their respiratory efficiency. We hypothesize that fish also synchronize their locomotion and respiration. Due to the close proximity of the operculum and the pectoral fins, water jetting out of the operculum could affect flow over the pectoral fins, possibly changing locomotory efficiency. Using a Photron high-speed video system, we filmed three bluegill sunfish swimming at speeds ranging from 0.5 to 1.5 body lengths per second. We then determined phase differences between pectoral fin beating (locomotion) and opercular jetting (respiration). Data show that the bluegill and do indeed synchronize locomotion and respiration, and that this is constant across all three individuals and all swimming speeds. The operculum is open during fin abduction and closed during fin adduction, suggesting several mechanistic models, such as decreasing the time necessary for developing lift forces to act or avoiding interaction with the propulsion phase.