Pygmy killer whale
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|Pygmy killer whale|
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The pygmy killer whale (Feresa attenuata) is a small, rarely seen cetacean of the oceanic dolphin family (Delphinidae). It derives its common name from sharing some physical characteristics with the killer whale. It is the smallest species that has "whale" in its common name. In fact, "killer" may be more apt in the case of the pygmy killer whale than its larger cousin; when a number of pygmy killers were brought into captivity in Hawaii and South Africa they were extremely aggressive—even killing other poolmates. A pod captured in Japan did not display such aggression.
Although it had been described by John Gray in 1874, until the early 1950s the pygmy killer whale was known only from two skulls kept at the British Museum. In 1954, Japanese cetologist Munesato Yamada published accounts of a "rare porpoise" discovered in 1952 by whale hunters working from Honshū. He wrote that the individuals he examined had skulls matching those in the museum and that the body had features similar to the killer whale, and proposed the common name lesser (or pygmy) killer whale. Despite its name and features, the pygmy killer whale is not closely related to the killer whale.
The scientific species descriptor attenuata is Latin for 'tapering' and refers to the gradual narrowing from the head to the tail fin.
The pygmy killer is an average-sized dolphin (a little larger and heavier than a grown man) and may easily be confused at sea with other species, in particular the melon-headed whale. The body is robust and dark-colored. The cape is particularly dark. The head is rounded without a beak. The sides are lighter and the belly is often white. Several individuals have been seen with a white lining around the mouth and chin. The dorsal fin is tall and slightly falcate.
The pygmy avoids human contact. Some spy-hopping, breaching and other active behavior has been recorded but it is not an acrobatic animal.
These dolphins always move in groups, usually of 10 to 30, but occasionally much, much larger.
Data from strandings, which seem to be common in the species, indicates a diet of cephalopods and small fish. They have been observed attacking, killing and eating other cetacean species such as the Common Dolphin.
Population and distribution
The only population estimate is of 38,900 individuals in the eastern tropical Pacific Ocean. However the species has a wide distribution in tropical and sub-tropical waters world-wide. They are sighted regularly off Hawaii and Japan. Appearance in bycatch suggest a year-round presence in the Indian Ocean near Sri Lanka and the Lesser Antilles. In the Atlantic individuals have been observed as far north as South Carolina on the west coast and Senegal on the east. The species is purely oceanic.
The pygmy killer whale is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). The species is further included in the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU)
- Whales, Dolphins and Porpoises, Mark Carwardine (1995) ISBN 0-7513-2781-6
- Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. (2008). Feresa attenuata. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 24 March 2009. Database entry includes justification for why this species is listed as data deficient
- National Audubon Society: Guide to Marine Mammals of the World ISBN 0-375-41141-0
- Article Pygmy Killer Whale Meghan Donahue and Wayne Perryman pps 1009-1010 in Encyclopedia of Marine Mammals (1998) ISBN 0-12-551340-2
- Estimates of cetacean abundance and distribution in the eastern tropical Pacific P.R. Wade and T. Gerrodette (1993) Rep. Int. Whal. Comm. 43, 477-493
- Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
- Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
- Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region