Meeting Abstract

40-4  Sunday, Jan. 5 08:45 - 09:00  Comparative biomechanics of submerged and emerged walking in the epaulette shark (Hemiscyllium ocellatum) TRAVIS, KG*; KAWANO, SM; California State Uni., Long Beach; George Washington Uni.

Epaulette sharks (Hemiscyllium ocellatum) are benthic fishes that commonly use a tetrapod-like “walking-trot” gait to move along the substrate and will occasionally emerge out of water to navigate reef flats. Given these characteristics, epaulette sharks have been considered a functional analog for tetrapodomorph fishes and may exhibit similar locomotor biomechanics as living salamanders (a common modern analog for early tetrapods). This study aims to broaden analyses of the locomotor biomechanics of epaulette sharks while fully submerged vs. partially emerged to allow for more direct comparisons to published work on salamander locomotion. We collected 3D kinematics of the paired fins between both environmental conditions while simultaneously obtaining 3D ground reaction forces (GRFs) from the fins. Subadult sharks were recorded under submerged (n=3) and partially emerged (n=2) conditions with two high-speed video cameras (200 fps) while individuals moved along a waterproof 3D force plate. Preliminary results from a single individual suggest that the average maximum protraction angle of the pectoral fins was higher when partially emerged compared to fully submerged while the maximum protraction of the pelvic fins remained relatively consistent. Additional analyses to compare the GRFs between paired fins and environmental conditions are ongoing and would yield a more comprehensive evaluation of the functional role of paired fins during aquatic and terrestrial locomotion. Comparisons of these results to salamander locomotor biomechanics would then enable quantitative analyses on the functional consequences of using fins versus limbs for a walking-trot gait, potentially providing insights on the biomechanical limitations of moving onto land.