The 78 living species currently recognized in the Order Cetacea are divided into 2 Suborders Odontoceti (toothed whales) and Mysticeti (baleen whales). All representatives of a third suborder, Archaeoceti (ancient whales), are extinct. It is generally agreed that cetaceans are the most derived of all mammals (with the possible exception of bats). Evolved from terrestrial ancestors, they have totally adapted to living in the water, and have no need to come ashore, even for resting or reproduction.

See the ETI (Marine Mammals of the World) for Order Cetacea and Suborders Odontoceti, Mysticeti and Archaeoceti.

Alternative forms for Cetacea : cetacean, cetaceans, Whales, Dolphins, and Porpoises.