Dolphins can swim and sleep at the same time. For 8 hours, the entire brain is awake. The left side then sleeps for 8 hours. When it wakes up, the right side sleeps for 8 hours.

Dolphins are capable of imitation and memorization.

The common dolphin averages 2.5 m in length and 74 kg in weight.

A dolphin’s flipper has five digits and nearly the same bone structure as a human arm and hand.

A dolphin’s can detect underwater sounds from 15 miles away.

Dolphins are fishlike in form, with streamlined, hairless bodies.

Dolphins jump out of the water to conserve energy.

The best known species are the common dolphin (Delphinus delphis) and the bottle-nosed dolphin (Tursiops truncatus).
As early as 340 B.C. Aristotle considered dolphins and related creatures to be mammals.

A dolphin can remember a specific tone far better than can a human.

Dolphins produce an enormous variety of sounds, up to frequencies ten times those heard by human beings.