Meeting Abstract
P2.63 Monday, Jan. 5 Turning performance of batoid rays: Limitations of a rigid body PARSON, J.M.*; FISH, F.E.; NICASTRO, A.J.; West Chester Univ.; West Chester Univ.; West Chester Univ. jp589840@wcupa.edu
The ability to maneuver is critical to the locomotor performance of batoid rays, but can be constrained by the inflexibility of the body. Turning motions are therefore affected by the motions of the expanded and mobile pectoral fins. Turning radius (maneuverability) and turning rate (agility) were measured from overhead video recordings of rays in a large pool during unrestricted swimming. The rays were characterized as swimming by oscillatory movements of the pectoral fins (Aetobatus narinari, Myliobatis freminvillii and Rhinoptera bonasus) or by undulations of the fins (Dasyatis americana and Dasyatis centroura). Oscillatory rays maneuvered by either powered or unpowered gliding turns, whereas undulatory rays turned using asymmetrical undulations of both pectoral fins. Underwater observations showed that both rays used banking while turning, which ranged from 15-70o. No statistical differences were found between mean turning parameters between the two locomotor types. However, minimum turn radius and maximum turning rate were respectively smaller and larger for oscillatory rays (0.7 m; 44.4o/s) compared to undulatory rays (1.0 m; 30.4o/s). Rays can reduce the rotational inertia of the body by banking and bending the fins dorsally to change the distribution of mass, thereby overcoming the mechanical constraints on turning that are imposed by the structure of their rigid bodies. Despite compensation by possessing flexible appendages, rays still have lower agility compared to flexible-bodied swimmers.
