Dolphins

...are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 LT, 11 ST) (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.

All dolphins are toothed whales belonging to the sub-order, odontocetes, of the order cetacea (see section on humpback whales for more information). As a group, dolphins are often referred to as "small" cetaceans, even though some of them are quite large, attaining lengths of over 20 feet. In addition, although the terms dolphins and porpoises are often used interchangeably, they really refer to two different types of animals.

Porpoises belong to the family Phocoenidae. They are generally smaller and more robust species. Most attain about 5-7 feet in length. Porpoises have no distinct beak, or rostrum. Their foreheads slope almost uniformly to the tip of their snout, and their teeth are spade-like in shape. The family Phocoenidae is rather small, and consists of only six members. There are no porpoises found in Hawaiian waters.

Dolphins belong to the family Delphinidae. Dolphins possess a distinct beak. Their teeth are conical in shape. Most species of dolphins are larger than porpoises, with the males usually being larger than the females. The family Delphinidae is the largest and most diverse family of the cetacean order and includes 26 living species. Several species of dolphins are found in Hawaiian waters.