The common dolphin has been divided into two species, the short-beaked common dolphin and the long-beaked common dolphin. As per their names, beak length is important to distinguish between the two species, though there are other defining features. Based on individuals from California, they both have a bold, dark and light hour-glass pattern on their sides, coming to a V below their dorsal fin, but the color of the Long-beaked common dolphin is noticeably muted. The Long-beaked common dolphin’s body is more slender, with a less rounded head. It has more teeth than other dolphins, having 47 to 67 pairs in each jaw.
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Long-beaked common dolphins are restricted to the Indian, Pacific and Atlantic Oceans. Their range includes areas of southern and western Africa, a good part of western South America, central Mexico to central California coastal Peru, areas around Taiwan, Japan, and Korea and, and possibly near Oman. These dolphins typically prefer shallow, subtropical, tropical and warmer temperate waters nearer to the coast (generally within 90-180 km) as well as on the continental shelf.
Long-beaked common dolphins typically occur in social groups from 100 to 500 individuals, but have occasionally been seen in larger schools with thousands of members. These large groups are thought to be made up of smaller sub-groups numbering 10-30 that may be related or possibly separated by age and/or gender. These gregarious, energetic animals are commonly observed swimming quickly, "breaching", "porpoising", and often engaging in other active surface behavior. They often approach ships in order to "bowride" for extended periods. These dolphins can dive to at least 900 ft (280 m), holding their breath for as long as 8 minutes to eat prey. Groups may sometimes work together in herding schools of prey.
Mostly Long-beaked common dolphins are carnivores (piscivores) - they eat small schooling fish (e.g., hake, anchovies, pilchards, and sardines), cephalopods (e.g., squid), and krill.
Little is known about the mating system of the Long-beaked common dolphin. Breeding usually occurs between spring and autumn, with a 10-11 month gestation. A single calf is born, about 2.5-3 ft (0.8-1 m) in length and weighing about 20 lbs (10 kg). There is an estimated interval between calving of 1-3 years. Weaning occurs after 14 - 19 months and the animals become mature when they are about 6.5 ft (2 m) long.
In some areas, such as East Africa, West Asia and the west and east coasts of South America, unknown numbers of these dolphins are being either directly exploited, or caught as bycatch. In West Africa and Peru in particular, increasingly there is concern about the numbers being caught for shark bait and human food.
No overall population estimate is available. According to the IUCN Red List resource, off California in the USA, in the northern part of their range, estimates range from 11,000 to 49,000, with an average of about 22,000 dolphins. Individuals found off California belong to a larger population that extends southward through Mexico, where there are estimated to be 55,000 individuals within the Pacific coast waters of the Mexican Exclusive Economic Zone and 69,000 in the Gulf of California. Around 15,000-20,000 dolphins are thought to live off South Africa. Overall Long-beaked common dolphins are classified as Data Deficient (DD) on the IUCN Red List.