Classification:The Common Dolphin is named from the Latin and Greek words for dolphin, referring to the fact that this was the species with which the Ancients were most familiar. There are now two recognised forms: Delphinus delphis, the short-beaked variety, and Delphinus capensis, the long-beaked.
Local Names: Saddleback Dolphin; White-Bellied Porpoise; Criss-Cross Dolphin; Hourglass Dolphin; Cape Dolphin.
Description:The Common Dolphin is slender and streamlined, with a long or short beak, depending on the geographical location. All forms vary slightly in size but are recognisable as Common Dolphins due to the tell-tale 'hourglass' pattern on each side. The dorsal cape is dark (brown, black, grey or purplish), dipping to a distinct 'V' beneath the fin. The tail stock is pale grey, darkening to black flukes. The underside is cream-white, and extends higher up the sides than in most dolphins. It is broken by one or two yellow or grey stripes that stretch from beak to beneath the 'V'-shaped dip. Another stripe - this one black - streaks from the dark flippers to the middle of the lower jaw. Higher on the sides, behind the eyes, is a yellow-tan patch which - together with the pale grey further back - forms the criss-cross 'hourglass' pattern. A dark line circles the eyes and leads to the grey-black beak, which can be white-tipped. In some geographical forms, these colours can appear to be muted, or slightly varied. There are 80-120 teeth per jaw. Common Dolphins range in size from 1.7m to 2.6m, and weigh between 70kg and 135kg.
Recognition at sea: Common Dolphins can be identified from the yellow-tan patch on either side, just behind each eye, and the dorsal cape's 'V'-shaped dip.
Habitat: Common Dolphins prefer waters with a surface temperature that is higher than 10ºC.
Food & Feeding: Common Dolphins prey on schooling fish (e.g. herring, pilchards) and squid. They have been known to adopt co-operative techniques when hunting (rather like the Orca) and have also been observed catching fish in mid-air.
Behaviour: Highly social, Common Dolphins can be seen in groups of up to 2,000 animals, although units of 10-500 are more usual. Active and exuberate, they bowride, breach, somersault, flipper-slap and lobtail. When porpoising, they often cannot be seen for the froth they produce - they leap as a co-ordinated whole. Also highly vocal, their cries - whistles, pulses and clicks - can be heard above water as they play around vessels.
Longevity: Unknown.
Estimated Current Population: Unknown.
The Influence of Man: This species is the target of fisheries in Japan, South America and the Azores. Accidental catches in fishing gear occur in the eastern tropical Pacific, the Mediterranean, Europe, China, Sri Lanka, South Africa, West Africa and New Zealand. Common Dolphins are the third most frequently caught dolphin in this manner. Any captive animals, though active and social in the wild, appear to be shy and easily agitated. Two computer-generated Common Dolphins were seen bowriding in the blockbuster movie Titanic - their appearance and behaviour was so accurate that it is hard to tell the difference between them and real Common Dolphins!
