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Oceanic dolphins are the members of the Delphinidae family of cetaceans. These aquatic mammals are related to whales and porpoises.
As the name implies, these dolphins tend to be found in the open seas, unlike the river dolphins, although a few species such as the Irrawaddy Dolphin are coastal or riverine.
Six of the larger species in the Delphinidae, the Orca and its relatives, are commonly called whales, rather than dolphins. They are also sometimes collectively known as "blackfish".
The Delphinidae vary in size from 1.2 metres and 40 kg (Heaviside's Dolphin), up to 7 metres and 4.5 tonnes (the Orca). Most species weigh between about 50 and about 200 kg. They are found worldwide, mostly in the shallower seas of the continental shelves, and all are carnivores, mostly taking fish and squid.
Taxonomy