SKIN DENSITY AND ITS INFLUENCE ON BUOYANCY IN THE MANATEE (TRICHECHUS MANATUS LATIROSTRIS), HARBOR PORPOISE (PHOCOENA PHOCOENA), AND BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS)

摘要: This study investigated how skin contributes to buoyancy control in the Florida manatee (Trichechus manatus latirostris), harbor porpoise (Phocoena phocoena), and bottlenose dolphin (Tursiops truncatus). Manatees are shallow divers their position water column hydrostatically. The two cetaceans relatively deep that hydrodynamically. Although cetacean had been hypothesized lower total body density (e.g., Dearolf et al. 2000, Nowacek 2001), its buoyant force not calculated. of skin, contribution buoyancy, was unknown. Skin densities 27 manatees, five porpoises, dolphins were measured volumetrically. mass used calculate force. Harbor (952 kg/m 3 ) (969 skins less dense than seawater, added 9 25 N positive force, respectively, buoyancy. By contrast, (1,121 contributed 56 negative which equaled 70% dense, pachyosteosclerotic ribs. Calculation forces skeleton, lungs demonstrates is positively at surface negatively depths 10 m.