Orca or Killer Whale – Orcinus orca
Habitat: Wide variety, common in cold, nearshore waters but also reported from polar ice pack to tropical oceanic islands. Individuals often develop feeding specialisations which restrict distribution.
Description: Powerfully built, robust torpedo-shaped body with conical head and indistinct beak. Colouration is striking black above, white below, with white patch above eye, white patch extending from belly to flanks, and less distinct grey saddle behind dorsal fin. Dorsal fin is all, triangular or sickle-shaped, centrally placed. Flippers broad and rounded. Teeth large and pointed.
Size: Females 5.6 – 5.7 m, males 9.4 – 9.5 m.
Weight: Females 2500 – 3000 kg, males 4000 – 5000 kg.
Lifespan: 60 – 90 years, females tend to live longer.
Distribution: Worldwide, from tropical to polar seas. In north-east Atlantic, most numerous around Iceland, Faroes, localised regions off west Norway. Widely distributed in small numbers around British Isles, mainly Atlantic seaboard and North Sea. Recorded in British waters year round but most commonly in coastal waters May – September, and offshore between Shetland and Norway and in north North Sea, November – March.
Diet & Feeding: Varied, including fish, squid, marine mammals, turtles, birds, although individuals or social groups usually specialise. Often uses tidal rips to capture fish such as salmon, cooperatively herding them into clusters. Cooperatively feeds on grey seal, with mature male making kill and allowing other pod members to feed. Intentional stranding to capture seals suggests large degree of social learning. Cooperative feeding on schooling herring well documented in Norway. Echolocation can detect schools of fish within a few km. Males tend to dive deeper than females.
Breeding: Births occur mainly in late autumn and winter. Mating probably peaks around October – November. Gestation period around 12 months, possibly up to 16; lactation period unknown, at least 12 months; calving interval at least 3, perhaps up to 9 years. Age at sexual maturity 15 – 16 years in male, 8 – 10 in female.
Conservation Status & Population: Listed by IUCN as lower risk, conservation dependent. Population estimates incomplete. 1987 survey of north Atlantic estimated 6618 animals. Has been hunted opportunistically in eastern Canadian Arctic, west Greenland, Faroes. Commercial captures primarily by Norway took 2455 whales between 1938 – 1981. Live capture off Iceland sporadically since 1975 for dolphinaria. May be affected by pollutants, oil slicks, acoustic threats from whale watching.
Striking black and white colouration, tall fin, sightings around British Isles mainly single individuals or small groups < 15.
Vocalisations: Includes variety of whistles of variable duration, mainly 6 – 12 kHz. High frequency 680 Hz 3.1 s call recorded in Iceland but never Norway. Underwater tail slaps produce broadband, multi-pulsed sounds which can be heard by other whales 3 – 4 km away. Mammal-eating orca often hunt silently. Suggested to be one of the few animals capable of vocal learning.