Species

Long-beaked common dolphin

The Long-beaked common dolphin (scientific name: Delphinus capensis) is one of two species of common dolphin.  Known for its long beak, this dolphin has the most teeth out of any dolphin in the world.  Both species of common dolphin are extremely colorful, however, the long-beaked common is typically less brightly colored.  In addition to slightly different coloring, beak size, and other physical characteristics; the long-beaked common dolphin differs from the short-beaked in that it prefers more shallow, warmer waters.  Also, the long-beaked common dolphin is less abundant than the short-beaked common dolphin. 

A marine mammal, the Long-beaked common dolphin is a member of the family Delphinidae, part of the order of cetaceans. This species, capensis, is so named because the original specimen for this dolphin was found on the Cape of Good Hope in the beginning of the 19th century. 

caption Long-beaked common dolphin (Delphinus capensis) Source: NOAA National Marine Fisheries Service

caption Size comparison of an average human and a common dolphin. Source: Chris Huh/Wikipedia

Conservation Status
Data Deficient

Scientific Classification

Kingdom: Animalia (Animals)
Phylum:--- Chordata
Class:------- Mammalia (Mammals)
Order:-------- Cetacea (Cetaceans)
Family:-------- Delphinidae (Porpoise)
Genus:----------Delphinus
Species:----------Delphinus capensis (Gray, 1828)

Common Names:
Arabian common dolphin
Arabian saddle-backed dolphin
Arabian saddleback dolphin
Baja-neritic common dolphin
Common dolphin
Malabar common dolphin
Malabar saddleback dolphin
Long-beaked common dolphin
long-beaked saddle-back dolphin
long-beaked saddle-backed dolphin
long-beaked saddleback dolphin
saddle-back dolphin
short-beaked saddle-backed dolphin
whitebelly porpoise

Physical Description

Long-beaked common dolphins are relatively small dolphins that can reach lengths of 6.0 to 8.5 ft (1.9 to 2.6 m) and weigh 160 to 500 lbs (80 to 235 kg).  Males are slightly larger than females.

Long-beaked common dolphins have a rounded melon, moderately long beak, and a sleek but robust body with a tall, pointy, falcate dorsal fin located in the middle of the back.   This species can be identified by its distinct bright contrasting coloration patterns.  There is a dull yellow/tan thoracic panel between the dark cape and white ventral patch forward of the dorsal fin.  The bold coloration forms a crisscrossing hourglass pattern below the dark saddle, and a lighter gray area extends up to the tail stock.  Narrow dark stripes extend from the lower jaw to the flipper and from the eye to the anal area.  The coloration and patterns of young and juvenile dolphins are muted and darker.  Morphologies can be distinct and also vary by geographic and regional areas.

Reproduction

Long-beaked common dolphins become sexually mature at around 6.5 ft (2 m) in length.  Breeding usually takes place between the spring and autumn, followed by a 10-11 month gestation period.  Females give birth to a single calf that is about 2.5-3 ft (0.8-1 m) long and weighs about 20 lbs (10 kg), and have an estimated calving interval of 1-3 years.

Lifespan

This dolphin species has a lifespan of approximately 40 years.

Behavior

Long-beaked common dolphins are usually found in large social groups averaging from 100 to 500 animals, but have been occasionally seen in larger herds of thousands of individuals.  These large schools are thought to consist of smaller sub-groups of 10 to 30 animals that are possibly related or separated by age and/or sex.  These gregarious, energetic dolphins are commonly seen swimming rapidly, breaching, porpoising, and frequently engaging in other surface active behavior. They will often approach ships to bowride for long periods of time.

Distribution

This dolphin is located circum-globally, and has a broad distribution in the Atlantic, Indian and Pacific Oceans.  Long-beaked common dolphins are commonly found along the USA west coast, from Baja California (including the Gulf of California) northward to about central California.  They are not known to occur along the U.S. Atlantic coast.  Distinct populations can be found off the coasts of California and Mexico, South America (Peru, Chile, Venezuela, Brazil, and Argentina), West Africa, South Africa, Madagascar, the Arabian Peninsula, India, Indonesia, China, Korea, and southern Japan.  The abundance and distribution of this species may change with varying oceanographic conditions. 

Habitat

Long-beaked common dolphins generally prefer shallow, tropical, subtropical and warmer temperate waters closer to the coast (usually within 50-100 nautical miles (90-180 km), and on the continental shelf.

Feeding habits  

Long-beaked common dolphins are capable of diving to at least 900 ft (280 m) and holding their breath for up to 8 minutes to feed on prey.  The majority of their diet consists of small schooling fish (e.g., anchovies, hake, pilchards, and sardines), krill and cephalopods (e.g., squid).  Dolphin groups may work together to herd schools of prey.  This species has 47-67 pairs of small sharp conical teeth in each jaw used for grasping prey.

Conservation status

IUCN notes this species as data deficient.

Currently, it is estimated that there are 25,000 to 43,000 animals off the U.S. coast of California.  There are estimated to be 15,000-20,000 off of eastern South Africa (Shirihai and Jarrett 2006).  Long-beaked common dolphins are not as abundant as short-beaked common dolphins. 

In 1997, NMFS (National Marine Fisheries Service) implemented the Pacific Offshore Cetacean Take Reduction Plan, which requires the use of pingers (an acoustic deterrence device) and six-fathom net extenders in the California/Oregon drift fishery to reduce bycatch of cetaceans, including long-beaked common dolphins. The Pacific Offshore Cetacean Take Reduction Team continues to meet and recommend measures to further reduce and achieve MMPA goals.

Threats

Long-beaked common dolphins have been incidentally taken as bycatch in a number of fisheries that include driftnets, gillnets, purse seines, and trawls. A small number of animals have been killed for food and bait in the Caribbean Sea, South America (e.g., Peru), West Africa and other offshore island seas. They have been taken in the Japanese drive fisheries as well.

References and Further Reading

  • Delphinus capensis Gray, 1828, Encyclopedia of Life
  • IUCN Red List (December, 2008)
  • Carwardine, M., Hoyt, E., Fordyce, R.E. and Gill, P. (1998) Whales and Dolphins. HarperCollins Publishers, London.
  • CITES (September, 2008) http://www.cites.org
  • Nowak, R.M. (1999) Walker's Mammals of the World. Johns Hopkins University Press, Baltimore, Maryland.
  • Perrin, W.F. (2008) Common dolphins. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. Eds. Encyclopedia of marine mammals. Second Edition. Academic press, Amsterdam.
  • NOAA Fisheries Service (December, 2008)
  • Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciara, G. (2003) Dolphins, Whales and Porpoises: 2002–2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC Cetacean Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK.
  • Natoli, A., Cañadas, A., Peddemors, V.M., Aguilar, A., Vaquero, C., Fernández- Piqueras, P. and Hoelzel, A.R. (2006) Phylogeography and alpha taxonomy of the common dolphin (Delphinus sp.). Journal of Evolutionary Biology, 19: 953 - 954.
  • Perrin, W.F. (2009) Pers. Comm.
  • WWF (December, 2008)
  • Heyning, John E., and William F. Perrin. 1994. Evidence for Two Species of Common Dolphins (Genus Delphinus) from the Eastern North Pacific. Natural History Museum of Los Angeles County Contributions in Science, no. 442. 1-35
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
  • Jefferson, Thomas A., and Koen Van Waerebeek. 2002. The taxonomic status of the nominal dolphin species Delphinus tropicalis van Bree, 1971. Marine Mammal Science, vol. 18, no. 4. 787-818
  • Mead, James G., and Robert L. Brownell, Jr. / Wilson, Don E., and DeeAnn M. Reeder, eds. 2005. Order Cetacea. Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd ed., vol. 1. 723-743
  • Perrin, W. (2010). Delphinus capensis Gray, 1828. In: Perrin, W.F. World Cetacea Database. Accessed through: Perrin, W.F. World Cetacea Database (accessed 2011-02-05)
  • Rice, Dale W. 1998. Marine Mammals of the World: Systematics and Distribution. Special Publications of the Society for Marine Mammals, no. 4. ix + 231
  • UNESCO-IOC Register of Marine Organisms
  • Wilson, Don E., and DeeAnn M. Reeder, eds. 1993. Mammal Species of the World: A Taxonomic and Geographic Reference, 2nd ed., 3rd printing. xviii + 1207
  • Wilson, Don E., and Sue Ruff, eds. 1999. The Smithsonian Book of North American Mammals. xxv + 750
  • van der Land, J. (2001). Tetrapoda, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 375-376
Glossary

Citation

Life, E. (2011). Long-beaked common dolphin. Retrieved from http://www.eoearth.org/view/article/154282

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