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Stenella coeruleoalba

Stenella coeruleoalba (National Oceanic and Atmospheric Administration)

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Superordo: Cetartiodactyla
Ordo: Cetacea
Subordo: Odontoceti
Infraordines: Delphinida
Superfamilia: Delphinoidea
Familia: Delphinidae
Genus: Stenella
Species: S. coeruleoalba

Name

Stenella coeruleoalba Meyen, 1833

References

* Stenella coeruleoalba on Mammal Species of the World.
* Mammal Species of the World: A Taxonomic and Geographic Reference, 2 Volume Set edited by Don E. Wilson, DeeAnn M. Reeder


Vernacular names
English: Striped Dolphin
Galego: Golfiño riscado
日本語: スジイルカ
Türkçe: Çizgili yunus

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The Striped Dolphin (Stenella coeruleoalba) is an extensively studied dolphin that is found in temperate and tropical waters of all the world's oceans.

Taxonomy

The Striped Dolphin is one of five species traditionally included in the genus Stenella; however, recent genetic work by LeDuc et al. (1999) indicates that Stenella, as traditionally conceived, is not a natural group. According to that study, the closest relatives of the Striped Dolphin are the Clymene Dolphin, the Common Dolphins, the Atlantic Spotted Dolphin, and "Tursiops" aduncus , which was formerly considered a subspecies of the Bottlenose Dolphin. The Striped Dolphin was discovered by Meyen in 1833. The specific name coeruleoalba (from Latin caeruleus 'dark blue' and albus 'white') refers to the characteristic blue and white stripes on the flanks.

Physical description

The Striped Dolphin has a similar size and shape to several other dolphins that inhabit the waters that it does (see Pantropical Spotted Dolphin, Atlantic Spotted Dolphin, Clymene Dolphin). However its colouration is very conspicuous and makes them relatively easy to distinguish at sea. The underside is white or pink. There are one or two black bands that circle the eye, and then run across the back, to the flipper. These bands widen to the width of the flipper which are the same size. There are two further black stripes running from behind the ear - one is short and ends just above the flipper. The other is longer and thickens along the flanks until it curves down under the belly just prior to the tail stock. Above these stripes the dolphin's flanks are coloured light blue or grey. All appendages are black as well. At birth, individuals weigh about 10 kg (22 pounds) and are up to a metre (3 ft) long. By adulthood they have grown to 2.4 m (8 ft) (females) or 2.6 m (8.5 ft) (males) and weigh 150 kg (330 lb)) (female) or 160 kg (352 lb) (male). Research suggest that sexual maturity was reached at 12 years in Mediterranean females and in the Pacific at between 7 and 9 years. Longevity is about 55–60 years. Gestation lasts approximately 12 months and there is a three or four year gap between calving.

In common with other dolphins in its genus, the Striped Dolphin moves in large groups - usually in excess of up to 1000's of individuals in size. Groups may be smaller in the Mediterranean and Atlantic. They may also mix with Common Dolphins. The Striped Dolphin is as capable as any dolphin at performing acrobatics - frequently breaching and jumping far above the surface of the water. Sometimes, it approaches boats in the Atlantic and Mediterranean but this is dramatically less common in other areas, particularly in the Pacific where it has been heavily exploited in the past.

The Striped Dolphin feeds on small pelagic fish and squid.

Population and distribution

The Striped Dolphin likes temperate or tropical, off-shore waters. It is found in abundance in the North and South Atlantic Oceans, including the Mediterranean and Gulf of Mexico, the Indian Ocean and the Pacific Ocean. Roughly speaking it occupies a range running from 40° N to 30° S. It has been found in water temperatures ranging from 10 to 26 degrees Celsius, though the standard range is 18-22 degrees. In the western Pacific, where the species has been extensively studied, a distinctive migration pattern has been identified. This has not been the case in other areas. The dolphin appears to be common in all areas of its range, though that may not be continuous in areas of low population density do exist. The total population is in excess of two million.

Human interaction

Japan has hunted Striped Dolphins in the western Pacific since at least the 1940s. During the "Striped Dolphin drive" heyday at least 8 thousand to 9 thousand individuals were killed each year and in one exceptional year 21,000 individuals were killed. Since the 1980s, following the introduction of quotas, this number has fallen to around 1,000 kills per year. Conservationists are concerned about the Mediterranean population which is threatened by pollution, disease, busy shipping lanes and heavy incidental catches in fishing nets.

Attempts have been made to keep the Striped Dolphin in captivity. However these have all failed, with animals dying within two weeks due to failure to feed.

Diet

The adult Striped Dolphin eats fish, squid, octopus, krill, and other crustaceans. Mediterranean striped dolphins seem to prey primarily on cephalopods (50-100% of stomach contents), while northeastern Atlantic striped dolphins most often prey on fish, frequently cod. They mainly feed on cephalopods, crustaceans, and bony fishes. They feed anywhere within the water column where prey is concentrated and they can dive to depths of 700 metres to hunt deeper-dwelling species.

References

1. ^ Mead, James G. and Robert L. Brownell, Jr (November 16, 2005). "Order Cetacea". in Wilson, D. E., and Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 723–743. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=14300089.
2. ^ Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. (2008). Stenella coeruleoalba. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 7 October 2008.

1. LeDuc, R.G., W.F. Perrin and A.E. Dizon (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Marine Mammal Science, vol. 15, no. 3:619-648.
2. Striped Dolphin by Frederick I. Archer II in Encyclopedia of Marine Mammals pp. 1201-1203. ISBN 978-0-12-551340-1
3. Whales Dolphins and Porpoises, Mark Carwardine, Dorling Kindersley Handbooks, ISBN 0-7513-2781-6
4. National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, ISBN 0-375-41141-0

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