Meeting Abstract
Epaulette sharks (Hemiscyllium ocellatum) use tetrapod-like walking with a variety of gaits that involve sequential fin movements to advance the animal forward. During walking, the fins rotate about the proximal insertion and undergo conformational changes to contact the substrate. The goal of this study was to quantify the three-dimensional (3D) kinematics of the pelvic and pectoral fins during steady walking. Three juvenile epaulette sharks were outfitted with markers along the fins and body and filmed submerged walking in a 50 L aquarium. We calibrated two GoPro Hero 5 Black cameras with overlapping views for 3D analysis and tracked marker movement in XMALab. We placed four markers at the proximal pectoral fin insertion and four markers along the pectoral girdle that were used to model pseudo-rigid bodies to quantify fin rotation in relation to the body axis using Autodesk Maya 2017. We used additional markers distributed throughout the distal and trailing fin edge to quantify the conformational changes of the fins. Fin rotation and conformation were compared to the velocity, duty factor, and stride frequency of the trials to determine the role of fins in walking performance. Our data show that both pelvic and pectoral fins rotate in three axes during walking, and that both fins undergo substantial conformational changes during walking. The fin rotation quantified in this study greatly exceeds that observed during yaw maneuvering in other shark species. The pelvic and pectoral fins and girdles, and associate musculature, of epaulette sharks are previously described as highly specialized to facilitate walking along the substrate. We suggest that this increased musculature and high degree fin rotation and flexibility allows this species a greater degree of control needed for more complex walking movements.
