Dolphins are sometimes thought of as the dogs of the sea because they are usually playful and friendly. They’re also among the smartest animals on Earth. Dolphins are water mammals. Scientists believe they’re as smart as chimpanzees or dogs. They live in rivers and oceans, but they must come up to breathe air.
A Dolphin is a cetacean mammal, related to whales and porpoises. Though people sometimes think ‘dolphin’ and ‘porpoise’ are the same thing, porpoises are not considered dolphins and have different physical features (Porpoises have a shorter beak and spade-shaped teeth) and they also behave in different way than a dolphin does. Porpoises and dolphins share a common ancestry, being of the Delphinidae mammal family.