Meeting Abstract

14.3  Monday, Jan. 4  Dorsal Fin Function in Spiny Dogfish and Bamboo Sharks during Steady Swimming MAIA, A.*; WILGA, C.D.; Univ. of Rhode Island amaia@mail.uri.edu

White-spotted bamboo sharks, Chiloscyllium plagiosum, inhabit complex reef habitats and are highly maneuverable. Spiny dogfish, Squalus acanthias, occupy a variety of coastal and continental platform habitats and use the water column for feeding, schooling and migration. Dorsal fin shape, area and location on the body differ between the two species. In order to determine whether these characteristics have an affect on fin function, steady swimming was replicated in a flow tank at 0.5 and 0.75BL.s^-1 in four individuals of each species. Dorsal and lateral views were recorded using high speed video and four tail beats per individual were analyzed for kinematics. The goals were to determine if the dorsal fins are moving independently of the body during steady swimming and if first and second dorsal fins have different kinematic patterns. Spiny dogfish first dorsal fin moves independently of the body with a higher amplitude at lower speeds, indicating a stabilizing function to counter increased instability. The first dorsal fin has a three dimensional conformation at maximum displacement. The second dorsal fin appears to be moving passively with the caudal portion of the body, although it can not be ruled out that the dorsal fin may augment thrust. Bamboo shark dorsal fins move in synchrony with the trunk, showing relatively higher amplitude of movement compared to dogfish at both speeds. First and second dorsal fins show a similar kinematic pattern with comparable displacements when corrected for axial displacement and appear independent of speed. The function of the dorsal fins during steady swimming differs in spiny dogfish and bamboo sharks. The first dorsal fin in spiny dogfish likely contributes to stability while the second dorsal fin, as well as both dorsal fins in bamboo sharks, appears to contribute to added thrust. Electromyography and fluid dynamics will verify these results.