The Tursiops truncatus (Bottlenose dolphin)
Bottlenose dolphins swim in groups, or pods, of ten to thirty. Their diets consist mainly of fish, which they locate using echolocation, the process of sending out small clicks and other sounds, and then wait for return signals that indicate foreign objects and possibly prey. Bottlenose dolphins can also communicate with each other through body movements and whistles that they emit from their blowholes. Dolphins also directly interact with humans, ranging from things such as fishing to military usage.
The system
Like us, dolphins have a closed cardiovascular system, with arteries and blood vessels. Their system actually adjusts to maintain its normal body temperature and conserve its body heat. Its arteries go through its flippers and fins, surrounded by veins. During exercise or swimming in warm waters, the dolphin's circulation changes to maintain normal temperatures. Blood is sent quickly out to the body, and is slowed down on its return to the heart.