Juvenile Justice System

Whales

Whales are a diverse and widely distributed group of fully aquatic placental marine mammals. They correspond to large members of the infraorder Cetacea, i.e. all cetaceans except dolphins and porpoises, as an informal and colloquial grouping. From a formal, cladistic standpoint, dolphins and porpoises are whales. Whales, dolphins, and porpoises are members of the order Cetartiodactyla, which includes even-toed ungulates. Their nearest living non-cetacean relatives are hippopotamuses, from which they and other cetaceans diverged approximately 54 million years ago. Baleen whales (Mysticeti) and toothed whales (Odontoceti) are thought to have shared a common ancestor approximately 34 million years ago.

Mysticetes is made up of four extant (living) families: Balaenopteridae (rorquals), Balaenidae (right whales), Cetotheriidae (pygmy right whale), and Eschrichtiidae (the pygmy right whale) (the grey whale). Odontocetes include the families Monodontidae (belugas and narwhals), Physeteridae (sperm whales), Kogiidae (dwarf and pygmy sperm whales), and Ziphiidae (beaked whales), as well as six families of dolphins and porpoises that are not whales in the informal sense. Whales are open-ocean creatures that can feed, mate, give birth, suckle, and raise their young at sea. Whales range in size from 2.6 meters (8.5 feet) and 135 kilograms (298 pounds) for dwarf sperm whales to 29.9 meters (98 feet) and 190 metric tons (210 short tons) for blue whales, the largest known animal.