All sharks are ectothermic (cold blooded), wich means that their body temperature depends on the temperature of the surrounding water. Among some fast swimming sharks (great white shark, porbeagle, maco shark) a body temperature above the surrounding water have been observed. This is possible because of heat exchange between the blood vessels. The hot blood coming from the muscles heats the cold, newly oxidized blood from the gills before it enters the muscles. For this to work, the veins and arteries that transports the blood to the muscles, have to lie very close to each other.

An increase by just a couple of degrees of the body temperature will double the muscular effect. Body temperatures of as much as 10-15 degrees above the surrounding water have been recorded in the great white shark.