False killer whale
Pseudorca crassidens
By: Nicole Le Boeuf
Edited by: Poul Vendel
The name:
The false killer whale is named as such for the tendency of fishermen to
confuse them with the 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 for "false" and the Latin
word orca for "some kind of whale". Crassidens is
formed from two Latin words, crassus which translates to "thick" or
"stout" and dens meaning "tooth". The false killer whale is one of several species
of toothed-whales that are called "blackfish" by fishermen.
The look:
False killer whales 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 its back. Their bodies are mostly black with some
grey regions on the head and
chest. The flippers are significant in that they have a hump midway down the
leading edge.
The size:
Adult false killer whales reach lengths around 5-6 m with males
being slightly larger than females. The false killer whale's maximum weight has been recorded at
tons.
At birth, Pseudorcas are usually around 1.5-2 m in length.
The location in Africa:
The false killer whale 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.
Interesting facts:
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. The false killer whale 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.
Human impacts:
Although occasional capture of false killer whales 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.
Status:
Insufficiently known.
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