Thursday, June 19, 2008

Dolphin


The majority of small-toothed whales are whales are called dolphins. They are mammals of the order Cetacea and the families Platanistidae, Delphnidae, and Grampidae and include about 50 species. All have a beaklike snout and sharp, conical teeth. The term porpoise is sometimes applied to many of the same species, but porpoises, strictly speaking, are members of the family phocaenidae teeth. The dolphin fish (mahi-mahi or dorado) is a sport fish related to the mackerels.

More dolphin species are about 2 m in length, the males averaging 10 to 20 cm longer than females. The largest is bottle nose dolphin, Tursiops truncates, well known in many public aquariums. This species may reach over 3 m in length and 200 kg in weight. The smallest species is the buffeo, Sotallia fluviatilis, of the Amazon River, it is rarely over 1.2 m in length and 30 kg in weight.

Dolphin are predators and feed on live food, except when trained otherwise in captivity. The primary food is fish, mostly open water types such as herring, mackerel, and sardines. Some species seem to prefer squid; occasionally shrimp and other crustacean are consumed. Food consumption is estimated at about 30 kg (66 lb) a day for an individual about 2.5 m (8.2 ft) in length and 100 kg (220 lb) in weight.

Dolphin can be found in virtually all the seas and oceans of the world. Some species are sharply restricted, but many, such as the common dolphin, Delphinus delphis, or the bottle nose dolphin, are found world wide. Several species are found in freshwater, notably the Ganges River dolphin. Platanista gangetica, the river of south America are the home of the long snouthed dolphin, Inia geoffrensis, and the buffeo. Dolphin are abundant in some area of the world. Off the coast of the Japan, population of the white-sided dolphin.

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