56.1 Thursday, Jan. 5 Synchronized Swimming: Coordination of pelvic and pectoral fins during augmented punting in stingrays BLEVINS, EL*; MACESIC, LM; MULVANEY, D; Harvard University, Cambridge, MA; Mount Holyoke College, South Hadley, MA; Florida Atlantic University, Boca Raton, FL email@example.com
Benthic animals live at a fluid-solid boundary, and therefore have access to multiple modes of aquatic locomotion—they can swim through the water, or use the nearby substrate to “walk.” Aquatic walking and similar substrate-dependent forms of propulsion have evolved multiple times in vertebrates: in lungfish, teleosts, salamanders, sharks and batoids. Within batoids, skates are benthic locomotion specialists, using uniquely adapted pelvic fins to “punt” along the substrate, pushing the body forward while the pectoral disc is kept still. In contrast, benthic rays, close relatives of skates, exhibit “augmented punting,” combining pelvic punting with pectoral undulations like those used during swimming. Studies of other benthic locomotors (e.g. frogfish, salamanders) have found both synchronous and asynchronous motions of fin/limb pairs depending on species and gait. In this study, we investigate how benthic rays coordinate fin pairs to combine benthic locomotion and swimming, hypothesizing that pelvic and pectoral fins are used synchronously during augmented punting to align the timing of thrust production. We used high-speed video to film dorsal and ventral views of freely-punting freshwater stingrays (Potamotrygon hystrix, n=5, disc length=9.10cm±0.224SD), and analyzed nine punting sequences per individual. We determined the timing of events in the pelvic punt cycle (thrust start, thrust end, and recovery phase), the time of the pectoral wave’s maximum and minimum height, and the stingrays’ distance-traveled and speed during pelvic and pectoral cycles. Pectoral wave maxima are tightly aligned to the end of the pelvic thrust cycle, confirming synchrony of fin pairs in pelvic-pectoral locomotion.