Stenella frontalis

Stenella frontalis, Photo: Michael Lahanas

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: Stenella frontalis

Name

Stenella frontalis Cuvier, 1829

References

* Stenella frontalis 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
Internationalization
English: Atlantic Spotted Dolphin
日本語: タイセイヨウマダライルカ
Türkçe: Atlantik benekli yunusu

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The Atlantic Spotted Dolphin (Stenella frontalis) is a dolphin found in the Gulf Stream of the North Atlantic Ocean. Older members of the species have a very distinctive spotted coloration all over their body.
Taxonomy

The Atlantic Spotted Dolphin was first described by Cuvier in 1828. There is considerable variation in the physical form of individuals in the species and specialists have long been uncertain as to the correct taxonomic classification. Currently just one species is recognised, however it is quite possible that a large, particularly spotty variant commonly found near Florida may be classified as a formal subspecies or indeed a species in its own right.

Description

The coloring of the Atlantic Spotted Dolphin varies enormously as they grow. Calves are a fairly uniform grey colour. When the calves are weaned, they then begin to get their spots. Juveniles have some dark spots on their belly, and white spots of their flanks. Their back and dorsal fin are a darker grey than the rest of the body. As the animal matures the spots became denser and spread until the body appears black with white spots at full maturation.

The Atlantic Spotted Dolphin has a 3-part coloration:

Dark gray back, lighter sides, and a white belly.

Measurements at Birth:

Length: about 35"-43" (90-110 cm)
Weight: unavailable

Maximum Measurments:

Length:

Male 7'5" (2.26 m)
Female 7'6" (2.29 m)

Weight:

Male 310 lb. (140 kg)
Female 290 lb. (130 kg)

These dolphins are a middle sized dolphin in both length and weight. At full size South American Spotted Dolphins are about 2.2-2.5 m in length. Compared to their much smaller pantropical spotted dolphin, the Atlantic spotted dolphin is more robust. It lives in common waters with the pantropical spotted dolphin and the bottlenose dolphin.

In common with other species in its genus the Atlantic Spotted is a gregarious creature. It is a fast swimmer, keen bow-rider and prone to acrobatic aerial displays.
Population and distribution

The species is endemic to the temperate and tropical areas of the Atlantic Ocean. It has been widely observed in the western end of the Gulf Stream, between Florida and Bermuda. It is also present in the Gulf of Mexico. More infrequent sightings have been made further east, off the Azores and Canary Islands. Northerly sightings have been made as far north as Cape Cod across to the south-western tip of Spain. They are certainly present further south too as far as Rio Grande do Sul in Brazil and across to west Africa. However the distribution is poorly understood in these areas.

About 20 years ago, there were only about 80 dolphins in the Bahamas. Now, 20 years later, there are almost 200 dolphins there. On account of their similar appearance to other dolphins in their range it is difficult to be sure of the Atlantic Spotted Dolphin's population. A conservative estimate is around 100,000 individuals.

Human interaction

Some Atlantic Spotted Dolphins, particularly some of those are around The Bahamas have become habituated to human contact. In these areas cruises to watch and even swim with the dolphins are common.

Atlantic Spotted Dolphins are an occasional target of harpoon fishermen and every year some creatures are trapped and killed in gillnets. However these activities are not currently believed to be threatening the survival of the species. This species lives in the mesopelagic layer of the ocean

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=14300090.
2. ^ HammondHammond, 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 frontalis. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 7 October 2008.

* 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,and there is no characteristics for survival. ISBN 0-375-41141-0
* Perrin, William F. (2002). "Stenella frontalis". Mammalian Species (702):1–6.

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