Wednesday, 6 January 2010

Killer whales

The Killer Whale (Orcinus orca), commonly referred to as the Orca and, less commonly,Blackfish, is the largest species of the dolphin family. They are found in all of the world'soceans, from the frigid Arctic and Antarctic regions to tropical seas. Killer Whales as a species have a diverse diet, although populations often specialize in particular types of prey. Some feed exclusively on fish, particularly salmon, and other populations hunt marine mammals such assea lions, seals, walruses and even large whales. As they are known to be predators of large sharks, Killer Whales are regarded as the ocean's apex predator.

There are up to five distinct Killer Whale types distinguished by geographical range, preferred prey items and physical appearance. Some of these may be separate races, subspecies or even species. Killer whales are highly social; some populations are composed of matrilinealfamily groups, which are the most stable of any animal species. The sophisticated social behavior, hunting techniques, and vocal behavior of Killer Whales have been described as manifestations of culture.

Although the Killer Whale is not considered to be an internationally endangered species, some local populations are considered threatened or endangered due to depletion of prey species,habitat loss, pollution by PCBs, historic capture for marine mammal parks, and conflicts with fisheries. In late 2007, the Killer Whales known as the "southern resident killer whales" were placed on the U.S. Endangered Species list. Because it is unlikely that all Killer Whales belong to a single species, the IUCN currently assesses the conservation status of the Killer Whale as data deficient.

Wild Killer Whales are not considered a threat to humans] although there have been cases of captive Killer Whales attacking, and in at least one instance, killing their handlers at marine theme parks. The Killer Whale features strongly in the mythologies of indigenous cultures. In Western cultures, it has had a reputation for being a fearsome predator, but in recent decades better understanding has led to widespread appreciation of the species.

The most famous killer whale was Keiko.

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