Dolphin is the common name of aquatic mammals within the
infraorder Cetacea. The term dolphin usually refers to the extant
families Delphinidae (the oceanic dolphins), Platanistidae (the Indian
river dolphins), named 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 named as
dolphins.
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