Dolphins are marine mammals that are closely related to whales and porpoises. They vary in size from 1.2 m and 40 kg, up to 9.5 m and 10 tonnes. Dolphins are among the most intelligent animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.The tail fin, called the fluke, is used for propulsion, while the pectoral fins together with the entire tail section provide directional control. The dorsal fin, in those species that have one, provides stability while swimming.
