Meeting Abstract

P1-99-A    Tail kinematics during upward and downward swimming in largemouth bass (Micropterus salmoides) Gong, M*; Jimenez, YE; Tytell, ED; Tufts University, Medford, MA; Tufts University, Medford, MA; Tufts University, Medford, MA ming.gong@tufts.edu

To control their depth in the water, fish can adjust the swimming bladder to help change buoyancy, but for more rapid changes, they can also actively swim up or down. Fish bend their bodies and use their fins to produce forces for swimming. For example, bending the caudal fins back and forth generates both thrust and lift. Many previous studies have examined the role of the caudal fin in producing thrust for forward motion, but few have examined its role in producing lift for vertical movement or changing orientation. Specifically, fish can twist their caudal fins, using the dorsal and ventral lobes independently. We hypothesized that during upward swimming and downward swimming, the dorsal and ventral lobes would beat differently compared to horizontal forward swimming, so that the tail would produce upward or downward forces. We predicted that when fish swim upward, the dorsal lobe of caudal fins would lead the ventral lobe during the oscillatory cycle; when they swim downward, the ventral lobe would lead; and when they swim horizontally forward, the motion would be more symmetric. Therefore, we quantified the 3D motion of the caudal fins of largemouth bass (Micropterus salmoides). We recorded upward, horizontal, and downward swimming bouts in a flow tank with high-speed cameras from rear and lateral views. We found that there were more dorsal-leading tail-beat cycles during upward swimming and more ventral-leading tail-beat cycles during downward swimming. During horizontal swimming, we found only symmetric tail motion. These results indicate that bass uses the dorsal and ventral lobes of the caudal fin independently to control their orientation and vertical movement in the water column.