PABST, D.A.*; HARRADINE, T.M.; MCLELLAN, W.A.; BARBIERI, M.M.; MEAGHER, E.M.; SCOTT, M.D.: Infrared thermography as a tool to assess thermal function of the bottlenose dolphin (Tursiops truncatus) dorsal fin
The dolphin dorsal fin is a dynamic thermal control surface. Body heat can be dissipated to the environment when blood is shunted to superficial veins and conserved when blood returns through deep veins. The goal of this study was to investigate the relationship between skin temperature and heat-flux across the fin. We used an infrared camera to measure dorsal fin temperatures of captive, exercising dolphins in Oahu, HI and wild dolphins in Sarasota, FL that had been temporarily captured. During captive dolphin experiments, heat flux and skin surface temperatures were recorded at multiple dorsal fin sites. The dorsal fin proved a thermally heterogeneous surface. In captive dolphins pre-exercise, superficial veins were obvious and could be 3-5oC warmer than surrounding tissue. Immediately after exercise vessels remained obvious although temperatures across the fin were elevated. As time after exercise increased, the entire dorsal fin surface warmed and discrete vessels were obscured, suggesting wide spread vasodilation. Heat flux and skin temperatures measured over vessels were higher than at other fin sites, and increased after exercise. In wild dolphins, discrete vessels were often not visible, suggesting that the entire surface of the dorsal fin was utilized as a thermal window.
