Orcas

Orcinus orca · also called the killer whale

Orcas are found in every ocean on the planet, from the pack ice of both poles to the tropics. They are the largest members of the dolphin family, and among the most socially complex animals in the sea.

What sets them apart is not size or speed but culture. Different orca populations hunt different prey, speak different dialects, and behave so differently from one another that they do not interbreed even where their ranges overlap.

Length: Up to 26 ft (8 m)
Weight: Up to 11 tons
Lifespan: 50–90 years; some females longer
Range: Every ocean
Diet: Varies by population — fish, seals, other whales

Conservation status

US Endangered Species Act: Southern Resident population listed Endangered (2005)
IUCN Red List: Data Deficient

The IUCN lists orcas as Data Deficient globally — not because they are doing well, but because scientists increasingly suspect that what we call one species may in fact be several. Individual populations are assessed separately, and some are in serious trouble.

Families that never separate

In resident orca populations, calves of both sexes stay with their mother for their entire lives. A pod is a matriline — a grandmother, her children, and her daughters' children, travelling together for decades.

Orcas are also one of only a handful of mammals known to go through menopause. Females stop reproducing in their thirties or forties but can live for decades afterward, and those older females often lead the group, particularly when food is scarce. The knowledge of where to find prey in a difficult year appears to sit with them.

Different orcas, different worlds

In the north-eastern Pacific alone, scientists recognise several distinct ecotypes. Residents eat fish and almost nothing else. Bigg's orcas — often called transients — hunt marine mammals such as seals and porpoises. Offshore orcas range far from the coast and appear to specialise in sharks.

These groups share the same waters but live entirely separate lives. They do not travel together, do not hunt together, and do not interbreed. Their calls are different, their body markings differ subtly, and genetic work suggests they have been diverging for a very long time.

Dialects

Each pod has its own set of calls, learned rather than inherited, and passed from one generation to the next. Related pods share parts of a repertoire the way neighbouring towns might share an accent. Researchers can identify which family a group belongs to from sound alone.

Because these calls are learned, they qualify as culture in the scientific sense — behaviour transmitted socially rather than genetically. Orcas are one of the clearest examples of animal culture we know of.

The Southern Residents

The best-studied orcas in the world are the Southern Residents, a single extended family that ranges the inland waters of Washington State and British Columbia. They have been listed as endangered in the United States since 2005.

The 2026 census put them at roughly 76 whales. Every individual is known, named and catalogued. Their decline is driven by three linked problems: a shortage of the Chinook salmon they depend on almost exclusively, underwater noise from vessel traffic that interferes with the echolocation they hunt by, and industrial contaminants that accumulate in their fat and pass from mother to calf in milk.

The three threats compound one another. A hungry whale burns its own fat reserves, which releases the contaminants stored there into its bloodstream.

Sources

Population figures and listing statuses change. These were checked in August 2026 — follow the links above for the current position.