by: Nicole Le Boeuf
The false killer whale is named as such for the tendency of fishermen to mistake them for killer whales as well as for its habit of using cooperative feeding techniques as it preys on smaller species of marine mammals. The word pseudorca is derived from the Greek word pseudos meaning "false" and the Latin word orca which means "some kind of whale". Crassidens is formed from two Latin words, crassus which translates to "thick" or "stout" and dens for "tooth". It is one of several species of toothed-whales that are called "blackfish" by fishermen.
They have long, slender bodies with rounded, but narrow foreheads with no beak. The dorsal fin is tall and falcate and is located midway down the animal's back. Their bodies are mostly black with some gray regions on the head and chest. The flippers are significant in that they have a hump midway down the leading edge.
Adult false killer whales reach lengths of approximately 5-6 m with males being slightly larger than females. Maximum weight has been recorded at 2000 kg. At birth, Pseudorcas are usually about 1.5-2 m long.
This species ranges from tropical to warm temperate waters, usually not found past 50 degrees either north or south. In African waters, there are records of this species offshore of the southern tip of South Africa, in the Mediterranean Sea, and throughout the Indian Ocean although observations are scattered.
False killer whales are one of the species of cetaceans that are frequently involved in mass strandings. In their case, the gregarious nature of this cetacean is believed to be a contributing factor. This species is known to not only feed on fish and squid, but to hunt cooperatively on other species of marine mammals such as smaller dolphins and the occasional humpback whale. Pseudorca have often been observed opportunistically attacking injured and confused dolphins escaping from purse seine nets in the Eastern Tropical Pacific tuna fisheries.
Although occasional capture of this animal occurs in nets and the long-line fisheries, direct kills occur in Japan and in its surrounding islands such as the notorious Iki Island where entire groups of these dolphins are driven to shore and killed. These events stem from the perception that the Japanese fishermen are in direct competition with the false killer whales for already depleted stocks of fish.
Insufficiently known.
VanWaerebeek, K. and W.M.A. DeSmet. 1996. A second confirmed record of the false killer whale Pseudorca crassidens (Owen, 1846) (Cetacea, Delphinidae) from West Africa. Mammalia, v60 i2 pp 319-322 (4).
Jefferson, T.A., Curry, B.E., Leatherwood, S. and J.A. Powell. 1997. Dolphins and porpoises of West Africa: A review of records (Cetacea: Delphinidae, Phocoenidae). Mammalia, v61 i1 pp 87-108 (22).
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