The dolphins have a smooth stream lined body. They are excellent swimmers. In the water they play, eat, sleep, and feed their babies. Normal fish can get their oxygen from the water but dolphins have to get their oxygen from the air like we do. Mostly all of them have hair. Mammals nurse their babies on milk. They are warm blooded. The dolphins' family have two branches. Porpoise are like dolphins and they also look very same. In fact, they are so much the same that there is only one sure way to tell them apart. And that is by the shape of their teeth. Porpoises have spade-shaped teeth. Dolphins have cone shaped teeth. Because dolphins and Porpoises are alike, many people call all of them Porpoises. The second reason is that there is another big fish. Other people prefer to use both names Dolphin-Porpoise. Bottle-nosed dolphins are about 7-11, and the way to tell a bottle-nose is by its mouth.