11. Bioengineering and Bio-thermal Fluid Dynamics

Spinecheek anemonefish (Amphiprion Biaculeatus) is a warm-water endemic species inhabiting shallow-water coral reefs and is known for its symbiosis with anemones. Its swimming behavior is based on a swimming motion (PCF: Pectoral-Caudal Fin) uses the pectoral and caudal fins differently according to the swimming environment. This study investigates the relationship between swimming behavior and hydrodynamic characteristics: flow and resistance changes occur when the spinecheek anemonefish swims in a restricted flume. This study aims to clarify the relationship between swimming behavior and changes in flow and drag. In a previous report (Kimura et al. (1)), we found that spinecheek anemonefish tended to swim close to the wall instead of swimming in the center of the flume when swimming in a square flume about 15 times wider and taller than the BL (Body Length) and that the lateral force-induced movement in the flume width direction during one cycle of swimming motion was averaged to The fish also showed a tendency to stay near the wall during one cycle of swimming motion, averaging out the lateral force-induced movement in the flume width direction. As a follow-up report, we observed behavioral changes in the swimming behavior of spinecheek anemonefish when the flume's width and the flowing water's velocity varied. The following observations were made. Spinecheek anemonefish tended to swim against the current by linking their pectoral and caudal fins to flow velocity. Still, at higher velocities, they showed a BCF (Body-Caudal Fin)-like swimming behavior in which they only used their caudal fin without using their pectoral fins. Furthermore, when the flume width was narrowed, the fish tended to move away from the wall and swim near the center of the flume when the flume clearance was extremely narrow.