Meeting Abstract

14.2  Monday, Jan. 4  Swimming kinematics of manta rays: Oscillatory winged propulsion by a large pelagic batoid FISH, F.E.; West Chester Univ., Pennsylvania ffish@wcupa.edu

The batoids swim by undulation or oscillation of their greatly expanded pectoral fins. The largest batoid is the manta ray (Manta birostris), that has highly tapered and relatively high aspect ratio pectoral fins, which are oscillated to provide thrust. Due to the large size of these rays and previous lack of availability in aquariums, kinematic descriptions were limited. To examine the swimming kinematics of manta rays, animals were video recorded at aquarium and field sites. Video-recordings were analyzed frame-by-frame. Animals swam at relative speeds up to 0.87 body lengths/s. The pectoral fin tip moved through a sinusoidal trajectory and the fin showed both chordwise and spanwise flexibility throughout the stroke cycle. The frequency of the fin stroke tended to increase with swimming speed and had an average stroke cycle of 0.31 Hz. The peak-to-peak amplitude remained constant with respect to swimming speed and averaged 0.74 body lengths. The body was stable during swimming with little pitching or heaving motions associated with the pectoral fin oscillations. However, manta rays are highly maneuverable and are cable of banking turns, inside loops and barrel rolls. As a large pelagic batoid, the movements of the manta ray display characteristics for stable, efficient swimming and high maneuverability.