FLAMMANG, B.E.; Harvard University: Comparative anatomy of intrinsic caudal musculature in fishes

The caudal fin is a key feature of the locomotor design of fishes, but the vast majority of research has focused on patterns of body undulation. Very little attention has been paid to the functional role of intrinsic tail muscles, which have the ability to control the caudal fin and generate thrust. Intrinsic caudal musculature of 9 genera of primitive and modern fishes was examined for anatomical comparison. Specifically, anatomy of the radialis, musculus flexor profundus, and hypochordal longitudinalis were described in terms of origin, insertion, fiber arrangement, and cross-sectional area for each genus when present, in order to elucidate evolutionary relationships that might directly impact the biomechanics of swimming in these fishes. Ecomorphological implications of variable caudal structure designs are also considered. Fishes studied include Squalus, Isurus, Parmaturus, Alopias, Polypterus, Acipenser, Lepisosteus, Amia, and Lepomis. This research forms the beginning of a larger project investigating the role of intrinsic caudal musculature in steady swimming, fast-starts, and maneuvering in basal and derived fishes.