Striped Dolphin
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 A Striped Dolphin in full flight
 Size comparison against an average human
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| Stenella coeruleoalba (Meyen, 1833) |
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 Striped Dolphin range
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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.
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[edit] 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 characterisitic blue and white stripes on the flanks.
[edit] 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 coloration is very conspicuous and makes them relatively easy to distinguish at sea. The underside is white or pink. There are one or two dark blue bands that run from the bottom of the eye to the flipper. These bands widen to the width of the flipper which are the same size. There are two further blue 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 colored light blue. The back, dorsal fin, melon and beak are dark blue. There is also a dark blue patch around the eyes. The lips are white. The tail stock is the same mid-blue color as the middle stripe of the flank. At birth individuals weigh about 10 kg and are up to a meter long. By adulthood they have grown to 2.4 m (females) or 2.6 meters (males) and weigh 150 kg (female) or 160 kg (male). Research suggest that sexual maturity was reached at 12 years in Meditterranean 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 100 individuals in size. Groups may be smaller in the Meditterranean 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 approaches boats in the Atlantic and Meditterranean 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.
[edit] 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 Meditterranean 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.
[edit] Human interaction
Japan has hunted Striped Dolphin in the western Pacific since at least the 1940s. During the "Striped Dolphin drive" heyday at least 8-9 thousand species 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 Meditterranean population which is threatened by population, 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.
[edit] References
- Cetacean Specialist Group (1996). Stenella coeruleoalba. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes a lengthy justification of why this species is dependent on conservation
- 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.
- Striped Dolphin by Frederick I. Archer II in Encyclopedia of Marine Mammals pp. 1201-1203. ISBN 01255513402
- Whales Dolphins and Porpoises, Mark Carwardine, Dorling Kindersley Handbooks, ISBN 0-7513-2781-6
- National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, ISBN 0-375-41141-0
[edit] External links
