THERMOREGULATION

Most sharks are cold blooded (ectothermic), meaning their body temperature is the same as the temperature of the water around them. Lamnid sharks ( great white, salmon, shortfin mako, longfin mako and porbeagle) can raise their internal temperature above that of the water around them ( endothermic). These sharks have vascular counter-current heat exchangers ( network of blood vessels called retia mirabilia)  that allow them to keep/store the heat generated by their muscles. 

RonWATKINS-1.jpg
Ryan mako 1.jpg
Salmon Shark 
(Lamna ditropis)
Shortfin Mako Shark 
(Isurus oxyrinchus)
great white shark .jpg
Great White
(Carcharodon carcharias)
Thermo shark slide.jpg
References

Anderson, S. D., & Goldman, K. J. (2001). Temperature measurements from salmon sharks, Lamna ditropis, in Alaskan waters. Copeia, 2001(3), 794-796.

Florida Museum. Shark Biology-Discover Fishes. https://www.floridamuseum.ufl.edu/discover-fish/sharks/shark-biology/