Taxonomy/Description

Common dolphins belong to the Mammalian Order Cetacea, in the suborder Odontoceti.  All toothed whales belong to the suborder Odontoceti, which is Latin for "toothed whales".  Common dolphins belong to the oceanic dolphin family, Delphinidae.  Other members of this family include the bottlenose dolphin, killer whale, and pilot whale.  The generic name, Delphinus, is Latin for "dolphin-like".  The specific name for the short-beaked common dolphin is delphis, which is Latin for "dolphin". The specific name for the long-beaked common dolphin, capensis, is Latin for "belonging to the Cape".  This may refer to the preference of coastal waters by this species.  Some scientists consider the long-beaked common dolphin of the Indian Ocean a separate species, called the tropical dolphin, Delphinus tropicalis.  The specific name, tropicalis, is Latin for "tropical".  Common dolphins are very colorful, with dark gray or brown dorsal shading, white undersides, and light gray or yellow lateral striping.  They are also recognizable by their prominent beaks.  Adults grow to 5-7ft in length and weigh 175-300lbs.  Short-beaked common dolphins are heavier than long-beaked common dolphins.

Long-beaked common dolphin Delphinus capensis

Habitat/Diet

Long-beaked common dolphins inhabit the temperate coastal waters of the eastern and northwestern Pacific Ocean, also including New Zealand, the western Atlantic Ocean, and the eastern and northern Indian Ocean.  Despite their name, "common" dolphins are unfamiliar to most people.  That is because they are a species that tends to live far off shore where the water is extremely deep.  They are so numerous that sailors of the open ocean frequently observed large pods.  The diet of common dolphins consists of squid and fish.

Short-beaked common dolphin Delphinus delphis

Behavior/Reproduction

Common dolphins are usually observed in groups of 1,000 individuals.  Smaller groups of 50-200 may form from these larger pods.  A plentiful food source may lead over 100,000 dolphins to a single location.  Gestation lasts 9-11 months.  Newborn calves are about three feet in length, weighing about 15lbs.  Calves are weaned at six months.  Depending on the region, sexual maturity for males is attained between 2-7 years, while females reach sexual maturity at 3-12 years.

Short-beaked common dolphin Delphinus delphis

Conservation

Common dolphins were species of dolphin affected by the tuna fishing industry.  Thousands drown in the fishing gear used to capture tuna.  Fortunately, necessary alterations of these nets now allow dolphins to escape.  The common dolphin population of the Black Sea declined substantially from the commercial use of dolphin oil and meat.  A population of one million was reduced to 50,000 individuals.  Legislation was instituted by the Soviet Union to protect the remaining population.  The population of common dolphins living in the eastern Pacific Ocean has been estimated at 3.1 million.  Common dolphins are not in danger of extinction, although human water pollution may still damage their habitat and health.