Meeting Abstract
Fast-start behaviors are high-energy maneuvers and may provide valuable insight into anatomical design in animals. Benthic stingrays are a group of dorso-ventrally flattened animals that possess broad pectoral fins, pelvic fins and a whip-like caudal fin with minimal surface area. This unique anatomy, compared to more common caudal swimming fishes, greatly influences the mechanics of locomotion (punting, walking and rajiform swimming), however, little is known about how these fish perform fast-starts. We used high-speed video to investigate the mechanics of escape responses of Potamotrygon motoro, a freshwater stingray from the Amazon. Maneuvers were initiated by a prod, and captured by five cameras so that all points of the ray were visible during the response: four cameras filming along the horizontal separated by 90°, and one camera filming a dorsal view. In contrast to caudal swimming fishes, benthic stingrays appear very dependent on waves of bending in their pectoral fins for escape. Rays modulate direction and two-dimensional speed of waves, in addition to fin area involved in the response, which strongly influences escape trajectory, speed and acceleration. Modulation of pectoral fin movements enables escape in all two-dimensional directions. In result, benthic stingrays appear unique to caudal swimming fishes in anatomy and fast start performance.
