Dolphins are in the same taxonomic classification as whales and porpoises, which is the "cetacean" classification. Cetaceans are animals that are mammals that live in water their whole life.
There are more than 70 different species of cetaceans, which are split into two categories: toothed whales and the baleen whales. The dolphin is a member of the toothed whale category. Dolphins are remarkable animals and hardy as they live throughout most of the shallow seas in the world. There are many different species of dolphins from the small 4-feet long Maui Dolphin to the large 25-foot long male orcas. Dolphins are also social animals as well and live in large groups, which is not necessarily a characteristic of all cetaceans.