Informal classification of marine mammals, closely related to whales and porpoises
A dolphin is a common name used for some of the aquatic mammals in the cetacean clade Odontoceti, the toothed whales. Dolphins belong to the families Delphinidae, along with the river dolphin families Platanistidae, Iniidae, Pontoporiidae, and probably extinct Lipotidae. There are 40 extant species named as dolphins.