Dolphins

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Dolphins

The majority of small tooth whales are called dolphins. They are mammals of the order Cetacea and the families Plantanistidae and Delphinidae and include about 50 species. All have a beak like snout and sharp, conical teeth. The term porpoise is sometimes applied to many of the same species, but porpoises, are members of the family Phocaenidae and have a blunt snout and spade or chisel shaped teeth. The 1. dolphin fish, is neither a dolphin nor a porpoise. It is a sport fish related to the mackerels.
Most dolphin species are about 6 ft in length, the males averaging 4 to 8 in longer than females. The largest is the bottle-nose dolphin which can reach over 9ft in length and weigh 440 lbs! The smallest species is the buffeo, found in the Amazon River. The buffeo rarely grows over 3.9 ft in length and 66 lbs in weight, really smalled compared to the bottle_nose.
Dolphins feed on live food and are predators, except when trained otherwise in captivity. The primary food is fish, mostly things like herring, mackerel, and sardines. Some species seem to prefer squid, occasionally, shrimp and other crustacean are consumed, and even mollusk shells have been found in their stomach contents. Food consumption is estimated at about 66 lb a day for an individual about 8.2 ft in length and 220 lb in weight.

Physiology
The body is sleek and smooth and the hairless skin is rubbery to the touch. Most species have jaws that protrude into a beak like snout. Above the upper jaw is a large mass of fat and oil-containing tissue forming the so-called "melon" that looks much like a bulging forehead.
The anterior appendages contain the skeletal remnants of five digits that form the flippers, which the animal uses primarily as stabilizers, although occasionally in an oar like fashion. The hind appendages are virtually absent and consist of a pair of small pelvic bones, deeply embedded in the connective tissue at the base of the tail. The dor...