The orca or killer whale (Orcinus orca) is a toothed whale belonging to
the oceanic dolphin family, of which it is the largest member. Killer
whales have a diverse diet, although individual populations often
specialize in particular types of prey. Some feed exclusively on fish,
while others hunt marine mammals such as seals and other species of
dolphin. Killer whales are apex predators, as no animal preys on them.
They can be found in each of the world's oceans in a variety of marine
environments (from Arctic and Antarctic regions to tropical seas). Killer
whales are highly social; some populations are composed of matrilineal
family groups (pods) which are the most stable of any animal species.
Their sophisticated hunting techniques and vocal behaviours, often
specific to a particular group and passed across generations, have been
described as manifestations of animal culture. The International Union for
Conservation of Nature assesses the orca's conservation status as data
deficient because of the likelihood that two or more killer whale types
are separate species. Some local populations are considered threatened or
endangered due to prey depletion, habitat loss, pollution (by PCBs),
capture for marine mammal parks, and conflicts with human fisheries. In
late 2005, the southern resident killer whales, which swim in British
Columbia and Washington state waters, were placed on the U.S. Endangered
Species list. Wild killer whales are not considered a threat to humans and
no fatal attack on humans has ever been documented, but there have been
cases of captive orcas killing or injuring their handlers at marine theme
parks. Killer whales feature strongly in the mythologies of indigenous
cultures, and their reputation in different cultures ranges from being the
souls of humans to merciless killers.
