Marine mammals thrive in widely varying temperatures. Dolphins, for example, swim in warmer, coastal regions that can easily be heated by the sun. Dolphins also spend extended periods of time on dives in the deep, cold water. To endure the rapidly fluctuating temperatures, these animals must use adaptive techniques to control their internal body temperature. On September 27th in 1975, researchers from the School of Medicine at the University of Hawaii published a new paper on temperature regulation in the Hawaiian Spinner Dolphin.
The Hawaiian Spinner Dolphin’s core temperature, according to the paper, ranges from 36.1°C (97.0°F) to 37.9 °C (100.2°F). The temperatures in the extremities can be quite different, depending on the environmental conditions. This suggests that the dolphins use the extremities (like the fins) to release unwanted heat. Veins and arteries that flow through the superficial regions can be intentionally dilated or closed, depending on if heat must be released or retained, respectively.
Two other factors majorly influence core temperature of the dolphins. When the dolphins are active, their internal temperature rises. Also, solar radiation simply heats the dolphins.
For more information on temperature regulation, see the paper itself:
Hampton, IFG., Whittow, GC. 1975. Body temperature and heat exchange in the Hawaiian spinner dolphin, Stenella longisrostris. Comparative Biochemistry and Physiology 55: 2, 195–197.
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