Cetacean is the word for all species of whale, dolphin, and porpoise. There are about 80 different species of cetacean and many, including the Indus and Ganges river dolphins, the southern right whale, and the beluga whale, are endangered. The first cetaceans lived on land, around 60 million years ago. Today they live in seas, oceans, and some rivers all over the world - but they are mammals, not fish.