Pygmy Killer Whale

Pygmy Killer Whale
Size comparison against an average human
Conservation status
Data deficient (IUCN)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti Family: Delphinidae Genus: Feresa Species: F. attenuata
Binomial name
Feresa attenuata Gray, 1875
Pygmy Killer Whale range

The Pygmy Killer Whale (Feresa attenuata) is a small, rarely-seen cetacean of the oceanic dolphin family (Delphinidae). It derives its common name from the fact that it shares some physical characteristics with the orca ("killer whale"). In fact, "killer" may be a more apt name in the case of the Pygmy Killer Whale than its larger genetic cousin. When a number of Pygmy Killers were brought into captivity in Hawaii and South Africa they were extremely aggressive—even killing one another. A third herd captured in Japan did not display such aggression. Until the early 1950s the Pygmy Killer Whale was only known from two skulls kept at the British Museum. The first description was recorded by John Gray in 1874. In 1954 Japanese cetologist Muneasto Yamada published accounts of a "rare porpoise" discovered by whale hunters working from Honshū in 1952. He wrote that the individuals he examined had skulls matching those in the Museum but that also the body had similar features to the Killer Whale, and proposed the common name Lesser (or Pygmy) Killer Whale. The scientific species descriptor attentuata is Latin for 'tapering' and refers to the gradual narrowing from the head to the tail fin of the dolphin.

Description

The Pygmy Killer is of average size amongst dolphins (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-coloured. The cape is particularly dark in tone. The head is rounded with no 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 is an uncooperative animal. It is usually difficult to approach. Some spy-hopping, breaching and other active behaviour has been recorded but it is not an acrobatic animal. These dolphins always move in groups, usually about 10 to 30 in size but occasionally substantially larger. They have been observed attacking, killing and eating other cetacean species such as the Common Dolphin. Further information on maturation on longevity is unavailable due to a paucity of data. Data from strandings, which seem to be common in the species, indicates a diet of cephalopods and small fish.

Population and distribution

The species appears to be naturally rare. The only population estimate is of 38,900 individuals in the eastern tropical Pacific Ocean (see reference [4]). However the species has a wide distribution in tropical and sub-tropical waters world-wide. Sightings are reported regularly off Hawaii and Japan. Accidental fishing catches 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.

Beaching

In August, 2007, three Pygmy Killer Whales beached themselves at North Myrtle Beach, South Carolina. After unsuccessful attempts to return them to the water they were determined to be too weak to survive and were euthanized.

References

• Cetacean Specialist Group (1996). Feresa attenuata. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes justification for why this species is listed as data deficient

1. National Audubon Society: Guide to Marine Mammals of the World ISBN 0-375-41141-0
2. Article Pygmy Killer Whale Meghan Donahue and Wayne Perryman pps 1009-1010 in Encyclopedia of Marine Mammals (1998) ISBN 0-12-551340-2
3. Whales, Dolphins and Porpoises, Mark Carwardine (1995) ISBN 0-7513-2781-6
4. 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

External links

• Whale and Dolphin Conservation Society