Cardiovascular sytem
The bottlenose dolphin's cardiovascular system, like other mammals, is a closed system. their hearts have four chambers like humans. Their heartbeats tend to slow down as a way to conserve oxygen while diving. A major usage of the cardiovascular system in the bottlenose dolphin is actually to adjust its body temperature, as part of a process known as thermoregulation. A dolphin's flippers, flukes, and dorsal fin are contain veins that are in turn surrounded by arteries. The heat of blood travelling through the arteries transfers over into the veins instead of being released into the environment, allowing the dolphin's body temperature to be balanced. In cold temperatures, circulation in these areas may decrease while it increases around the body's core. The opposite occurs if the dolphin needs to shed away excess heat.