Killer Whale

Killer Whale, the largest of the dolphin family, which probably has a larger range of world coverage than any other cetacean. Killer whales occur in all oceans, on the high sea, and close to shore. However, they are more common in the colder (more productive) waters of both hemispheres than in the tropics. Killer whales are mainly black or deep brown, with striking white patches from lower jaw to belly, above the eye, and a fainter grey-white saddle patch just under and behind the dorsal fin. They are sexually dimorphic in size, with females reaching 8.5 m (27.5 ft) and males to 9.8 m (31.9 ft) as fully grown adults. All killer whales have a large prominent dorsal fin midback, but that of the adult male continues to grow, until it is a triangular “sail” up to 1.8 m (5.9 ft) tall. The flippers are also distinctive; they are large and oval, and are unlike those of any other toothed whale.

Killer whales feed on fish, squid, marine birds including penguins, pinnipeds, and cetaceans. They have even been seen taking down a blue whale, a member of the largest species on Earth. In most areas, killer whales appear to specialize; in the Pacific Northwest of the United States and Canada, for example, resident populations feed mainly on salmon and other nearshore fishes while more transient populations take especially harbour seals and porpoises. Killer whales occur in group sizes of lone animals to well over 50. They tend to cooperate during hunting, especially when feeding on warm-blooded animals such as penguins, pinnipeds, and cetaceans. In several places in the southern hemisphere they habitually beach themselves briefly as they rush on to shore to take seals or sea lions in the turbulent surf zone. Residents may cover a several hundred square kilometre area; while transients often rapidly transect an area, moving well over 1,000 km (600 mi) along a shoreline in a matter of days.

The sexual dimorphism of killer whales hints at a polygynous mating society, with one male mating as “group master” with several females. However, killer whale groups that have been studied tend to be remarkably stable, with males and females staying in their natal groups (or pods) for life. It is likely that mating therefore does not occur within the pod as much as between pods when they meet, to keep inbreeding at a minimum. Killer whales echolocate by sending out from their heads high-frequency click sounds that bounce off prey and other objects and whose echoes allow the whales to “see” by sound. They communicate with rapid-fire clicks that sound like rasps and screams. When on the prowl for marine mammals (which all have acute hearing underwater), killer whales can be remarkably silent for hours.

Killer whales are an important object of mythology for many indigenous people, especially the Native Americans of the Pacific Northwest. They have not been hunted extensively by humans, although killer whales were taken by some shore whaling operations. They are perceived by many near-shore fishermen to be in competition with human fisheries resources. Killer whales have been taken as aquarium show animals from the Pacific Northwest and off Iceland.

Scientific classification: Killer whales are the largest member of the family Delphinidae of the suborder Odontoceti (the toothed whales) of the order Cetacea. It is classified as Orcinus orca.