killer whale

killer whale

killer whale or grampus, a large, rapacious marine mammal, Orcinus orca, of the dolphin family. Male killer whales may reach a length of 30 ft (9 m) and females half that length. The killer whale is black above, with a sharply contrasting white oval patch around each eye; its belly is white with white markings projecting up along the animal's sides. It has a high, triangular dorsal fin midway between head and tail, and broad, paddle-shaped flippers. The killer whale is worldwide in distribution. It is a swift and ferocious animal, armed with more than four dozen sharp teeth, and is the only cetacean (see whale) that feeds regularly on birds or mammals. Killer whales eat seals, sea birds, and fish, and in packs they will even attack larger whales. The female gives birth to a single calf, up to 7 ft (2.1 m) long, following a gestation period of approximately one year. Females mature in 6 to 7 years, males in 12. They are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Cetacea, family Delphinidae.
or orca

Killer whale (Orcinus orca).

A species (Orcinus orca) of toothed whale found in all seas from the Arctic to the Antarctic. Largest of the dolphins, the male may be 30 ft (9 m) long and weigh over 10,000 lbs (4,500 kg). The killer whale is black, with white on the underparts, above each eye, and on each flank. The snout is blunt, and the strong jaws have 40–50 large, sharp, conical teeth. Killer whales live in groups of a few to about 50 individuals. They feed on fishes, cephalopods, penguins, and marine mammals; though they are fierce predators of seals and even other whales, there is no recorded instance of a killer whale attacking a human. They are often kept in captivity and trained as performers in marine shows.

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The False Killer Whale (Pseudorca crassidens) is a cetacean and one of the larger members of the oceanic dolphin family (Delphinidae). It lives in temperate and tropical waters throughout the world. As its name implies, the False Killer Whale shares characteristics with the more widely known Orca ("killer whale"). The two species look somewhat similar and, like the orca, the False Killer Whale attacks and kills other cetaceans. However, the two dolphin species are not closely related.

The False Killer Whale has not been extensively studied in the wild by scientists; much of the data about the dolphin has been derived by examining stranded animals.

The species is the only member of the Pseudorca genus.

Description and behavior

This dolphin has a slender body with a dorsal fin that may be a foot high. One of the species' distinguishing characteristics is a bend and bulge (usually called the "elbow") half-way along each of the flippers. The tips of the tail fin are pointed and the middle of the tail has a distinct notch. The False Killer is uniformly coloured a dark grey to black. It grows to about 6 m long, may weigh 1,500 kg and lives for about 60 years.

The False Killer Whale is a social animal, living in groups of 10–50. It is a fast and very active swimmer. It may breach or jump clear of the water and will often land on its side with a big splash. On other occasions the dive may be very graceful, leaving very little wake at all. It will readily approach boats and bow- and wake-ride. It may also emerge from the water head held high upwards and with the mouth open, revealing some of its 44 teeth.

Population and distribution

Although not often seen at sea, the False Killer Whale appears to have a widespread, if rare, distribution in temperate and tropical oceanic waters. They have been sighted in fairly shallow waters such as the Mediterranean Sea and Red Sea as well as the Atlantic Ocean (from Scotland to Argentina), the Indian Ocean (in coastal regions and around the Lakshwadweep islands) and the Pacific Ocean (from the Sea of Japan to New Zealand and the tropical area of the eastern side).

The total population is unknown. The eastern Pacific was estimated to have in excess of 40,000 individuals and is probably the home of the largest grouping.

The false killer whale and a dolphin have mated in captivity and produced a fertile child.. This is apparently the first mating between two different species that has produced fertile offspring, i.e., without postzygotic barriers. This offspring is called a 'Wolphin'.

Human interaction

The False Killer Whale has been hunted, but not extensively, in the West Indies and Indonesia. In Japan, a small number of these cetaceans are killed every year.

False Killers have long caused anger amongst fishermen fishing for tuna and yellowtail. The dolphins take the fish from the longlines used by the fishermen. This led to a concerted effort from Japanese fisherman working from Iki Island to deplete the species in the area - 900 individuals were killed for this purpose between 1965 and 1990.

On 2 June 2005 up to 140 (estimates vary) False Killers were beached at Geographe Bay, Western Australia. The main pod, which had been split into four separate strandings along the length of the coast, was successfully moved back to sea with only one death after the intervention of 1,500 volunteers coordinated by the Department of Conservation and Land Management.

Several public aquariums in the world have False Killer Whales on display.

References

  • National Audubon Society: Guide to Marine Mammals of the World ISBN 0-375-41141-0
  • Encyclopedia of Marine Mammals ISBN 0-12-551340-2
  • BBC News: Beached whales saved in Australia (http://news.bbc.co.uk/1/hi/world/asia-pacific/4602429.stm)
  • MSNBC: Whale-dolphin hybrid has baby wholphin (http://www.msnbc.msn.com/id/7508288/)

External links

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