Cetacean Basics

Dolphins, whales and porpoises belong to the group of marine mammals called CETACEANS [sa-TAY-shuns]. Although they look like fish, dolphins and whales are air-breathing mammals. They have a hairless streamlined body, flippers and a tail with horizontal flukes. But like fish, they cannot live out of water. Cetaceans are the only mammals that spend their entire lives in water.

Dolphins and whales are warm-blooded creatures, their body temperatures being about that of humans. An insulating layer of blubber beneath the skin helps to conserve heat. There are no external ears. Cetaceans give birth to live young that are nourished on the mother's milk.

Dolphins and whales must come to the surface at regular intervals to breathe. If for any reason a cetacean is trapped under water it will drown. The nostrils (blowhole) are located on top of their head. When they come to the surface, they open their nostrils and exhale a spout of moist air mixed with particles of water (blow).

More information can be found here.