mammals of the families delphinidae (ocean dolphins), iniidae, lipotidae, pontoporiidae, and platanistidae (all river dolphins). The common Name dolphin is applied to small cetaceans having a beaklike snout and a slender, streamlined body, whereas porpoises are small cetaceans with a blunt snout and rather stocky body. Dolphins are the most agile of the cetaceans and some of the speediest. They have remarkable group precision and regularity of movement.
dolphins swim at a speed of 3-7 miles per hour, but have been recorded at 25 mph