Orca

Name and taxonomy

Carl Linnaeus described the orca in 1758, in the tenth edition of Systema Naturae. Conrad Gessner wrote an earlier account in 1558, after a dead orca washed up in the Bay of Greifswald. The genus name Orcinus comes from the Latin orca, which meant a large-bellied pot. Some writers link the name to Orcus, a Roman god of the underworld, but the zoological code rejects that story. The Romans used orca for these animals, and probably borrowed a Greek word for whales. The orca is the only living species in its genus.

Old English names include blackfish and grampus, and the second is now rare. Since the 1960s the name orca has slowly replaced killer whale in everyday speech. Scientists have proposed splitting the species into several species or subspecies. A 2024 study named the fish-eating residents and mammal-eating transients of the North Pacific as separate species. The Society for Marine Mammalogy accepted them only as subspecies, pending a global review.

Evolution and relatives

The oceanic dolphin family, Delphinidae, holds 35 species and first appeared about 11 million years ago. The orca line probably branched off soon after the family arose. It resembles the false and pygmy killer whales and the pilot whales, but the resemblance misleads. One gene study placed its closest living relatives among the snubfin dolphins of the genus Orcaella. A 2018 study instead placed it beside a group that holds Lagenorhynchus and Cephalorhynchus dolphins. A 2019 study found that it sits apart from almost every other dolphin.

The orca also has several ecotypes that differ in prey, calls and body markings. Four types, A to D, live in Antarctic waters, and DNA suggests that types B and C deserve species rank. Type D orcas from sub-Antarctic seas may be a species of their own.

Appearance

The orca is mostly black with sharply edged white areas. The lower jaw and the belly are white, and the white runs back to two lobes on the flanks. An oval white patch sits behind and above each eye. A grey saddle patch lies behind the dorsal fin. Newborn calves show yellow or orange where adults show white. Some Antarctic orcas look brown or yellow because diatoms coat their skin.

Males typically measure 6 to 8 metres and weigh over 6 tonnes. Females measure 5 to 7 metres and weigh about 3 to 4 tonnes. The tallest male dorsal fin stands about 1.8 metres high, more than twice the height of a female's fin. A male's fin is a tall triangle, while a female's fin curves backward. The flippers are broad, rounded paddles, and the snout is blunt with no beak. The jaw carries 10 to 14 pairs of large conical teeth that interlock when the mouth shuts. A blubber layer 7.6 to 10 centimetres thick keeps the body warm. Researchers identify individuals from nicks on the dorsal fin and the shape of the saddle patch.

Habitat and range

Orcas live in all oceans and most seas, which makes them the most widespread cetacean. They prefer cool water at high latitudes and stay near coasts more than in the open ocean. The densest populations swim off Norway, along the Aleutian Islands, in the Gulf of Alaska and around Antarctica. They are also common off British Columbia, Washington, Oregon, Iceland and the Faroe Islands. GBIF holds occurrence records from 111 countries.

In the Antarctic they push right up to the pack ice and swim into open leads inside it. In the Arctic they are summer visitors, and they now travel deep into Hudson Strait as the sea ice shrinks. They normally hunt at depths of 20 to 60 metres but can dive to 300 metres for food. A few orcas have swum 160 kilometres up the Columbia River, and others entered the Fraser and Horikawa rivers. Migration is poorly understood, and the same residents return to British Columbia each summer. Where those animals spend the winter remains unknown after decades of study.

Diet and hunting

The orca is an apex predator, and no wild animal hunts an adult. Across its range it eats over 140 species, including fish, squid, seals, whales, seabirds and turtles. A single orca eats about 227 kilograms of food a day. Each population specialises, and the choice of prey shapes its whole way of life. Fish-eating residents of the northeast Pacific take salmon for 96% of their diet, and Chinook make up 65% of that. Norwegian orcas herd herring into a tight ball with bubbles and flashes of their white bellies. They then slap the ball with their tails and stun up to 15 fish at a time.

Mammal-eating transients chase dolphins and porpoises until they tire, then ram them or leap onto them. Off Argentina and the Crozet Islands, orcas slide onto beaches to seize sea lions and elephant seals. Antarctic type B orcas swim together to make a wave that washes a seal off its ice floe. In New Zealand they hunt rays and sharks, and elsewhere they flip great white sharks to reach the liver. Pods also attack grey, humpback, sperm and minke whales, and mostly target calves. In 2019 orcas killed blue whales off Western Australia on three occasions. Resident orcas sometimes kill porpoises and seals without eating them.

Behaviour and social life

Orcas spend their days foraging, travelling, resting and socialising. They breach, slap their tails and spy-hop, which means holding the head above the water to look around. These displays may serve courtship, communication, play or the removal of parasites. They can reach 56 kilometres per hour in a burst, and a pod may travel 160 km in a day. Some orcas have been seen carrying a dead salmon on the head like a hat.

Only elephants and the higher primates live in societies as complex as an orca pod. A resident matriline is a mother, all her children, and her daughters' children in turn. The average matriline holds 5.5 animals, and up to six generations can travel together. Members separate for only a few hours, to mate or to hunt. One to four related matrilines form a pod, and pods with a shared dialect form a clan. Transient groups are smaller, often a female with one or two of her offspring. Some transient males rove alone and join groups only when a female is ready to mate.

Orcas teach their young, and a Crozet mother pushes her calf onto the beach and pulls it back when needed. Alaskan pods learned to strip fish from longlines and beat every trick the fishermen tried. In 2025 a Salish Sea orca rolled strands of bull kelp along its body, the first recorded tool use in the species. Researchers describe the dialects and hunting methods that pass from mother to calf as animal culture.

Communication and senses

Like all cetaceans, orcas rely on sound to find their way, to hunt and to talk. They make three kinds of sound: clicks, whistles and pulsed calls. Clicks serve echolocation, so an orca can find and judge prey in dark water. Every pod has a dialect of discrete calls, and residents use seven to 17 call types. A dialect stays stable for generations, and a calf learns it from its mother. Newborns produce calls like their mother's, but with fewer types.

Residents call often, because salmon cannot hear them well. Transients stay quiet on the hunt, because seals and porpoises hear whale calls clearly. The eyesight is good above and below the surface, and the hearing is excellent. Sound enters through the lower jaw and travels to an ear-bone complex, as in other toothed whales. The ear openings are tiny holes behind the eyes with no outer flap. The brain is the second heaviest among marine mammals, after the sperm whale.

Reproduction and life cycle

Females mature at about 10 to 13 years and are most fertile around 20. Males mature at 15 but seldom father a calf before 21. A male seeks mates in other pods, so inbreeding stays rare. Gestation lasts 15 to 18 months, one of the longest of any mammal. A mother has one calf about every five years, and twins are almost unknown.

A newborn calf is about 2.4 metres long and weighs about 180 kilograms. The first months are dangerous, and 37 to 50% of calves die before seven months. Weaning starts at about 12 months and ends by the age of two. Every pod member helps to care for a calf. Females stop breeding at about 40 and can live for decades afterward, a menopause rare among animals.

Wild females that survive infancy live about 46 years on average, and males about 31. The oldest females reach 90 years. One southern resident, Granny, was claimed to be 105, though a biopsy suggested 65 to 80. Infanticide was first seen in the wild in 2016, when a male and his mother killed a calf off British Columbia.

Predators and threats

An adult orca has no natural predator. A young orca may be attacked by large sharks or by other orcas. A 2026 study found that transient orcas eat resident orcas, which researchers treat as predation between species. The threats that matter come from people.

Prey depletion is the greatest danger, and Pacific salmon stocks have fallen sharply. Orcas sit at the top of the food chain, so PCBs and other poisons build up in their blubber. A 2018 study in Science warned that this pollution could cut many populations dramatically. Norwegian Arctic orcas carry more PCBs, pesticides and flame retardants than polar bears. Ship noise, naval sonar, oil spills and boat traffic all disturb them. After the Exxon Valdez spill, about half of one resident pod vanished, and the AT1 transients stopped breeding. In 2020 an orca found dead in England had a large piece of plastic in its stomach.

Population and conservation

The world population is at least 50,000, and the true number is probably higher. About 25,000 live in Antarctic waters and 8,500 in the tropical Pacific. Norway holds 500 to 1,500, and the seas around Japan about 2,321. The IUCN moved the orca from Conservation Dependent to Data Deficient in 2008. It did so because some types may prove to be separate, endangered species. The species sits on Appendix II of CITES, which regulates trade.

The southern resident community of Washington and British Columbia was listed as endangered in the United States in 2005. It once held about 200 animals, lost 48 to aquarium captures, and fell to around 75 by 2019. Canada set a 200-metre approach limit for boats in 2017, up from 100 metres. The AT1 transients of Prince William Sound numbered only seven by 2009 and will likely die out. Fewer than 50 orcas survive near the Strait of Gibraltar, where bluefin tuna stocks have fallen.

Relationship with humans

No wild orca has ever killed a person. A surfer in California was bitten in the 1970s, and a boy in Alaska was bumped in 2005. Captive orcas have attacked people nearly two dozen times since the 1970s, and some attacks killed. Tilikum, a male at SeaWorld, was involved in three deaths between 1991 and 2010. The 2013 film Blackfish told his story and turned public opinion against orca shows.

Whalers mostly ignored orcas until the larger whales ran out. Between 1954 and 1997 Japan took 1,178 orcas and Norway took 987. Fishermen shot them as pests, and 25% of orcas captured in Puget Sound before 1970 carried bullet scars. Between 1964 and 1976, 50 orcas were captured in the Pacific Northwest for display. Only one capture has happened in North American waters after 1976. The orcas of Eden, Australia, once helped whalers by herding baleen whales into the bay.

Since 2020, orcas off Spain and Portugal have rammed sailing boats and torn off rudders. As many as 500 vessels were damaged between 2020 and 2023, and a few sank. Whale watching is now a large industry, but too many boats stress the animals.

In culture and myth

The peoples of the Pacific Northwest Coast carve the orca into totem poles, masks and canoes. In Haida tradition, orcas live in towns beneath the sea and take human form when they dive. Haida stories say that a drowned person goes to live with them. The Kwakwaka'wakw saw the orca as the king below the waves, and said it kept sea lions as slaves and dolphins as soldiers. In Nuu-chah-nulth belief an orca may carry the soul of a dead chief. The Lummi word for orcas, qwe'lhol'mechen, translates as our relations beneath the waves.

The Tlingit of Alaska regard the orca as the sea's guardian and a friend to people. A 4,000-year-old burial at Port au Choix, Newfoundland, held a stone carving of an orca. Siberian Yupik tales say that orcas become wolves in winter, and hunters throw tobacco into the sea for them. The Ainu of Hokkaido called the orca Repun Kamuy, a sea god who drove whales to the shore. In Inuit folklore the akhlut is an orca that walks on land as a wolf.

Western writers feared it, and Pliny the Elder around AD 70 described a savage mass of flesh with teeth. Moby Doll, captured in 1964, proved docile and changed scientific opinion. The 1993 film Free Willy made a captive named Keiko famous, and he was released off Iceland in 2002.