The short-beaked common dolphin (Delphinus delphis) is a species of common dolphin. It has a larger range than the long-beaked common dolphin (D. capensis), occurring throughout warm-temperate and tropical oceans, with the possible exception of the Indian Ocean.^[4] There are more short-beaked common dolphins than any other dolphin species in the warm-temperate portions of the Atlantic and Pacific Oceans.^[5] It is also found in the Caribbean and Mediterranean Seas.

Physical characteristics

Homodont (similar) teeth of the Delphinus delphis

The short-beaked common dolphin is a medium sized dolphin, smaller than the more widely-known bottlenose dolphin. Adults range between 1.6 and 2 metres (5.2 and 6.6 ft), long, and can weigh between 70 and 235 kilograms (150 and 520 lb), although a range between 70 and 110 kilograms (150 and 240 lb) is more common.^[4] Males are generally longer and heavier.^[4] The color pattern on the body is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern colored light grey, yellow or gold in front and dirty grey in back.^[6] It has a long, thin rostrum with 50–60 small, sharp, interlocking teeth on each side of each jaw.^[7]

Taxonomy

The short-beaked common dolphin is a member of common dolphin genus, Delphinus within the dolphin family, Delphinidae. Until the mid-1990s, the different forms within Delphinus were not recognized as separate species, but were all considered members of the species D. delphis.^[4][5] Currently, there are two recognized species of Delphinus: the short-beaked common dolphin and the long-beaked common dolphin (D. capensis).^[1] The short-beaked common dolphin is generally smaller than the long-beaked common dolphin and has a shorter rostrum.

Behavior

Short-beaked common dolphin porpoising

Short-beaked common dolphins can live in aggregations of hundreds or even thousands of dolphins.^[5] They sometimes associate with other dolphin species, such as pilot whales.^[5] They have also been observed bow riding on baleen whales, and they also bow ride on boats.^[5] It is a fast swimmer (over 40 km/h), and breaching behavior and aerial acrobatics are common with this species.^[4]

Diet

The short-beaked common dolphin has a varied diet consisting of many species of fish and squid that live less than 200 metres (660 ft) deep.^[5]

Reproduction

The Short-beaked common dolphin has a gestation period of 10 to 11 months.^[5] The newborn calf has a length of between 70 and 100 centimetres (2.3 and 3.3 ft) and weighs about 10 kilograms (22 lb).^[4] For the Black Sea population, weaning occurs at between 5 and 6 months, but occurs later (up to about 19 months) in other areas.^[4][5] Typical interbirth interval ranges from 1 year for the Black Sea population to 3 years for eastern Pacific Ocean populations.^[5] Age of sexual maturity also varies by location, but can range between 2 and 7 years for females and 3 and 12 years for males.^[4][5]

Maximum lifespan is 35 years, but has been estimated at 22 years for the Black Sea population.^[4][5]

Conservation

The Mediterranean population of the short-beaked common dolphin Delphinus delphis is listed on Appendix I^[8], while the North Sea, Baltic Sea, Mediterranean, Black Sea and eastern tropical Pacific populations are listed on Appendix II^[8] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). The regional listing on Appendix I ^[8] means that this population has been categorized as being in danger of extinction and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It was listed on Appendix II^[8] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.

In addition, the species is also covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)

References

Cetaceans portal