Even the most brilliant of men failed to recognize that dolphins were a species of whales. Aristotle thought they were fish, though he did notice that they featured some mammal characteristics, such as hair, lungs, live birth and the nursing of calves.

Dolphins are considered to be of the Toothed Whale class because they lack Baleen, a horny material similar to fingernails in composition that grows as fringed filter plates from the upper jaws. Other Toothed Whales include Sperm Whales and Pilot Whales.

Scientists believe the ancestors of bottle-nosed dolphins live on land. Believe it or not, blood chemistry studies have shown that dolphins are "artiodactyls", or cows and camels! In addition, x-rays of flippers and pectoral fins showed a bone structure similar to the human arm and hand.

Dolphins are born with a small amount of hair on their beak, but in adulthood, only the hair follicles remain.

Differences between Dolphins and Porpoises

People often confuse dolphins and porpoises. Marine mammologists have recognized about a half-dozen species of porpoises worldwide and only two inhabit United States waters. They have recognized, however, more than 30 species of dolphins, many of which can be found in U.S. waters.

The main difference between the two is in the head area. Dolphins possess a "beak" and have a curved dorsal fin, while porpoises have a blunt head and a triangular dorsal fin.