Biogeography

Clymene dolphin

February 22, 2011, 4:51 pm
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Clymene dolphins (credits: Keith Mullin NOAA)

One of the most recently recognised species of dolphin, the Clymene dolphin remains among the least known of the Delphinidae. Clymene dolphins are marine mammals withing the family of Oceanic Dolphins, part of the order of cetaceans. In appearance it is very similar to the spinner dolphin (Stenella longirostris), which is largely why it was not recognised until 1981 as a distinct species. It is a small but stocky dolphin, with a beak of medium length and a dorsal fin that is triangular to nearly triangular. Males are larger and eavier than females, but both sexes have a white belly, light grey flanks and a dark grey cape, and a dark grey line runs down the top of the beak. The one distinctive feature that separates the Clymene dolphin in appearance from the spinner dolphin is the black marking, somewhat like a moustache, on top of the beak.

caption Leaping Clymene dolphin. Source: Robert Pitman, U.S. NOAA
caption Clymene dolphin size shown in comparison to adult human. Source: Chris Huh/Wikipedia

Conservation Status:
Data Deficient

Scientific Classification

Kingdom: Animalia
Phylum:--- Chordata
Class:------ Mamalia
Order:-------- Cetacea
Family:-------- Delphinidae
Genus:--------- Stenella
Species:--------Stenella clymene (Gray, 1850)

Common Names:
Atlantic spinner dolphin
Clymene dolphin
Helmet dolphin
short-snouted spinner dolphin  

Clymene dolphins appear to feed in midwater during the night, on fishes and squids, and many bear bite marks and scars from cookie-cutter sharks (Isistius brasiliensis).

These attractive and acrobatic dolphins have been observed riding the bow waves of boats and spinning out of the water like spinner dolphins, although the spins are not as high or as complex as those of performed by the spinner dolphin.

Physical description

The Clymene dolphin is a small dolphin that averages 1.8 meters in length. It has a short beak, a white belly, light gray sides, and a dark cape that dips in two points above the eye and below the dorsal fin. The facial markings are very distinct, including black eye rings, dark lips and snout tip, and a dark line on top of the snouts sometimes making a "moustache" near the apex of the melon. The cape sometimes has blotchy patches on the sides, and the dorsal fin is gray but bordered with dark margins. On average members of this species have 38 to 49 teeth on each side of the upper and lower jaws, which are slender and pointed.

Reproduction

Little information is currently available on the reproduction of the species, but some information is available for a close relative, the spinner dolphin, Stenella longiristris. Adult females of this species give birth to a single calf at two year intervals. Parturition most often occurs in early summer, but can occur in any season. The period of gestation is 11 months and calves are born about 75 centimeters long.

Behavior

Clymene dolphins travel in schools and may be segregated by sex. They often swim in close association with schools of spinner dolphins, Stenella longirostris. While swimming in close association with spinner dolphins, the Clymene dolphins remain clustered together. Schools of Clymene dolphins have also been seen in the company of common dolphins, Delphinus delphis, off  the coast of West Africa.

Clymene dolphins ride bow waves and are known to twist whilst leaping, but the spinning leaps are not as high or complex as those of the spinner dolphin. However, in the Gulf of Mexico Clymene dolphins have been observed to spin as much as the spinner dolphins do.

Clymene dolphins have been seen singly, amongst groups of spinner dolphins, and in large groups of around 100 animals. (5) These schools may sometimes be divided by age and sex, and sometimes swim in the company of a group of common dolphins (Delphinus delphis). Clymene dolphins appear to feed in midwater during the night, on fishes and squids, and many bear bite marks and scars from cookie-cutter sharks (Isistius brasiliensis).

These attractive and acrobatic dolphins have been observed riding the bow waves of boats and spinning out of the water, hence their name, although the spins are not as high or as complex as those of performed by the spinner dolphin.

Distribution

The Clymene dolphin can be found in tropical and subtropical waters of the Atlantic Ocean (eastern North America to West Africa), the Caribbean, and the Gulf of Mexico. In the United States it has been recorded as far north as New Jersey and along the coast lines of Texas and Louisiana. It has also been recorded as far south as southern Brazil.

Occurs in the tropical and warm temperate waters of the Atlantic Ocean, including the Caribbean and Gulf of Mexico.

Habitat

The Clymene dolphin is a deep water species that has only been observed at sea in waters with depths of 250 to 5000 m or deeper. It is not normally seen near the shore.

Food habits

The Clymene dolphin feeds mostly at night, when squid and small fish come to the surface of the water.

Threats

While the Clymene dolphin is currently not known to be facing major threats, the lack of research on this species means that the problems could simply be undocumented. These dolphins are harpooned in the Lesser Antilles and are sometimes caught in fishing gear in other areas. By-catch is likely to occur in many parts of its range, but is thought to be most significant in the eastern tropical Atlantic, off West Africa, where considerable numbers may be taken during overfishing by tuna purse seines.

There are scant records on numbers of Clymene dolphins captured or killed, but the species is occasionally taken by harpoon in the Lesser Antilles (Caribbean) small cetacean fishery. They are captured in gill-nets in Venezuelan waters, where they are used for longline shark bait and human consumption. They may also betaken in tuna purse seines in the eastern tropical Atlantic.

When captured in gill-nets, the Clymene dolphin is often used for shark bait and for human consumption. This species' tissue contaminant levels of heavy metals and other water pollutants have not been systematically recorded.

Further reading

  • Encyclopedia of Earth. Clymene dolphin (accessed 24 May, 2010)
  • M. Benton. 2000. Stenella clymene (On-line), Animal Diversity Web. (accessed 24 May, 2010)
  • P.S. Hammond, G. Bearzi, A. Bjørge, K. Forney, L. Karczmarski, T. Kasuya, W.F. Perrin, M.D. Scott, M.D., J.Y. Wang, R.S. Wells, and B. Wilson. 2008. Stenella clymene. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1. (accessed 24 May 2010)
  • M. Bryden and R. Harrison. 1986. Research on Dolphins. New York, NY: Oxford University Press. ISBN: 0198576064.
  • W. Doak. 1985. Dolphin Dolphin. New York, NY: Sheridan House. ISBN: 091137843X.
  • P. Folkens. 1994. Mammals of Texas: Clymene Dolphin.
  • L. Hansen, L. Higgins, T. Jefferson and K. Mullin. October 1994. Sightings of the Clymene Dolphin (Stenella clymene) in the Gulf Of Mexico. Marine Mammal Science, 10(4): 464-470.
  • J. Heyning. 1995. Whales, Dolphins, Porpoises: Masters of the Ocean Realm. Seattle, WA: University of Washington Press. ISBN: 0295974877.
  • Thomas A. Jefferson, Marc A. Webber, Robert Pitman and Brett Jarrett. 2007. Marine Mammals of the World. Rome: Academic Press  ISBN: 0123838533.
  • S.S. Ridgway and S. Harrison. 1994. Handbook of Marine Mammals, Volume 5: The First Book of Dolphins. San Diego, CA: Academic Press Inc. ASIN:B000J38O38
  • D. Robineau, M. Vely and J. Maigret. 1994. Stenella clymene (Cetacea, Delphinidae) From The Coast Of West Africa. Journal of Mammalogy, 75(3): 766-767.
  • P. Simoes-Lopes, G. Praderi, G. Paula, S. De. April 1994. The Clymene Dolphin, Stenella clymene (Gray, 1846), In The Southwestern South Atlantic Ocean. Marine Mammal Science, 10(2): 213-217.
  • IUCN Red List (November, 2008)
  • Jefferson, T.A. (2008) Clymene dolphin. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. Eds. Encyclopedia of Marine Mammals Second Edition. Academic Press, London.
  • CITES (December, 2007)
  • Perrin, W.F., Mitchell, E.D., Mead, J.G., Caldwell, D.K. and van Bree, P.J.H. (1981) Stenella clymene, a rediscovered tropical dolphin of the Atlantic. Journal of Mammalogy, 62 (3): 583 - 598.
  • Fertl, D., Jefferson, T.A., Moreno, I.B., Zerbini, A.N. and Mullin, K.D. (2003) Distribution of the Clymene dolphin Stenella clymene. Mammal Review, 33: 253 - 271.
  • Banks, R. C., R. W. McDiarmid, A. L. Gardner, and W. C. Starnes. 2003. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada
  • Banks, R. C., R. W. McDiarmid, and A. L. Gardner. 1987. Checklist of Vertebrates of the United States, the U.S. Territories, and Canada. Resource Publication, no. 166. 79
  • Bryden, M., R. Harrison. 1986. Research on Dolphins. New York, NY: Oxford University Press.
  • Doak, W. 1982. Dolphin Dolphin. New York, NY: Sheridan House.
  • Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College Station, Texas.
  • Fertl, D. "African Marine Mammals, Clymene Dolphin, STENELLA CLYMENE" (On-line). Accessed October 8, 1999.
  • Folkens, P. 1994. "Mammals of Texas: Clymene Dolphin" (On-line). Accessed October 9, 1999.
  • Gray, J. E., 1846. On the cetaceous animals. Pp. 13-53, in The zoology of the voyage of H.M.S. Erebus and Terror, under the command of Capt. Sir J. C. Ross, R. N., F. R. S., during the years 1839 to 1843 (Sir J. Richardson and J. E. Gray, eds.) [1844-1875]. 1:39. E. W. Janson, London, 2 vols.
  • Hansen, L., L. Higgins, T. Jefferson, K. Mullin. October 1994. Sightings of the Clymene Dolphin (STENELLA CLYMENE) in the Gulf Of Mexico. Marine Mammal Science, 10(4): 464-470.
  • Hershkovitz, Philip. 1966. Catalog of Living Whales. United States National Museum Bulletin 246. viii + 259
  • Heyning, J. 1994. Whales, Dolphins, Porpoises: Masters of the Ocean Realm. Seattle, WA: University of Washington Press.
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
  • Jefferson, T., S. Leatherwood, M. Webber. 1993. Marine Mammals of the World. Rome: FAO and UNEP.
  • Jefferson, Thomas A., and Barbara E. Curry. 2003. Stenella clymene. Mammalian Species, no. 736. 1-5
  • Mazzaralla, K. 1998. "Clymene Dolphin (STENELLA CLYMENE)" (On-line). Accessed October 8, 1999
  • 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
  • North-West Atlantic Ocean species (NWARMS)
  • Perrin, W. (2010). Stenella clymene (Gray, 1850). In: Perrin, W.F. World Cetacea Database. Accessed through: Perrin, W.F. World Cetacea Database on 2011-02-05
  • Perrin, W. F., E. D. Mitchell, J. G. Mead, D. K. Caldwell, and P. J. H. van Bree. 1981. Stenella clymene, a rediscovered tropical dolphin of the Atlantic. Journal of Mammalogy, vol. 62, no. 3. 583-598
  • Poss, S. "Species At Risk in the Gulf Of Mexico" (On-line). Accessed October 9, 1999 .
  • Rice, Dale W. 1998. Marine Mammals of the World: Systematics and Distribution. Special Publications of the Society for Marine Mammals, no. 4. ix + 231
  • Ridgway, S., S. Harrison. 1994. Handbook of Marine Mammals, Volume 5: The First Book of Dolphins. San Diego, CA: Academic Press Inc..
  • Robineau, D., M. Vely, J. Maigret. 1994. STENELLA CLYMENE (Cetacea, Delphinidae) From The Coast Of West Africa. Journal of Mammalogy, 75(3): 766-767.
  • Simoes-Lopes, P., P. Praderi, G. Paula, S. De. April 1994. The Clymene Dolphin, STENELLA CLYMENE (Gray, 1846), In The Southwestern South Atlantic Ocean. Marine Mammal Science, 10(2): 213-217.
  • 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 F. Russell Cole. 2000. Common Names of Mammals of the World. xiv + 204
  • 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). Clymene dolphin. Retrieved from http://www.eoearth.org/view/article/151273

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