How many species of dolphins are there?

There are 33 known species of marine dolphins and another four species of dolphins that live in both the ocean and in rivers. The most commonly known dolphin is the bottlenose dolphin, while species such as the killer whale and pilot whale are not really whales at all, but dolphins. read more

The dolphins comprise the extant families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the new world river dolphins), and Pontoporiidae (the brackish dolphins), and the extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species of dolphins. read more

There are at least 40 species of dolphin and porpoise (there is some argument about whether some species are subspecies of another), and very little is known about most of these. Population estimates range from several million for some species. read more