Dolphin In Blue Water Stock Image

A dolphin belongs to the kingdom of animals, vertebrates, mammals. A dolphin lives in water. There are salt-type and fresh-type dolphins. Some kinds of salt-types are spinners, bottle-nosed, and common. Dolphins are a widely distributed and diverse group of aquatic mammals. They are an informal grouping within the order Cetacea, excluding whales and porpoises, so to zoologists the grouping is paraphyletic. The dolphins comprise the extant families Delphinidae, Platanistidae, Iniidae, and Pontoporiidae, and the extinct Lipotidae. There are 40 extant species of dolphins. Dolphins, alongside other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates. Cetaceans` closest living relatives are the hippopotamuses, having diverged about 40 million years ago.