Dolphin

Dolphin, any of a family (Delphinidae) of small-toothed whales living in schools and feeding mainly on fish. The largest, the killer whale (Orcinus orcat), also feeds on seals. The best-known is the bottle-nosed dolphin (genus Tursiops), a highly intelligent mammal with an amazingly developed system of echolocation for finding food and avoiding obstacles. A second family of dolphins (Platanistidae) lives in fresh water, and includes the Chinese lake dolphin and the blind susu, or Ganges dolphin. The dolphin has been threatened by reckless tuna fishers whose nets entangle the fish.