False Killer Whale

False killer whales are large marine predators. They are the fourth-largest extant species of oceanic dolphin, exceeded in size only by the orca and the two species of pilot whales. Males are about 10–15% larger than females: females reach a maximum size of 4.5–5 m (15–16 ft) in length and 1,200 kg (2,600 lb) in weight, and males 6 m (20 ft) long and 2,200 kg (4,900 lb). Newborns can be 1.5–2.1 m (5–7 ft) long. Coloration is black or dark gray, slightly lighter on the underside. The body is slender with an elongated, tapered head without a beak. The dorsal fin is sickle-shaped; the flippers are narrow, short, and pointed, with a distinctive bulge on the leading edge of the flipper. Body temperature ranges from 36–37.2 °C (96.8–99.0 °F), increasing during activity. The teeth are conical; there are 14–21 in the upper jaw and 16–24 in the lower.

The false killer whale appears to have a widespread presence in tropical and semitropical oceans. The species has been found in temperate waters, but these occurrences were possibly stray individuals, or associated with warm water events. It generally does not go beyond 50°N or below 50°S. It usually inhabits open ocean and deep-water areas, though it may frequent coastal areas near oceanic islands. Distinct populations inhabit the seas near the Hawaiian Islands and in the eastern North Pacific.

The false killer whale is thought to be common around the world, though no total estimate has been made. The population in the Eastern Pacific is probably in the low tens-of-thousands, and ~16,000 near China and Japan. The population around Hawaii has been declining.

The false killer whale has been known to interact non-aggressively with some dolphins: the common bottlenose dolphin, the Pacific white-sided dolphin (Lagenorhynchus obliquidens), the rough-toothed dolphin (Steno bredanensis), the pilot whales, the melon-headed whale, the pantropical spotted dolphin (Stenella attenuata), the pygmy killer whale, and Risso's dolphin. They have been shown to engage in depredation at fisheries with killer whales (Orcinus orca), though their diets differ with the killer whales and false killer whales preferring swordfish and smaller fish respectively.

The false killer whale is known to be much more adaptable in captivity than other dolphins, being easily trained and highly sociable with other species, and as such it has been kept in several public aquariums around the world, such as in Japan, the United States, the Netherlands, Hong Kong, and Australia. Individuals were mainly captured off California and Hawaii, and then in Japan and Taiwan after 1980. It has also been successfully bred in captivity. Chester, an orphaned calf that had been stranded near Tofino in 2014 and rescued by Vancouver Aquarium, probably died from a bacterial erysipelas infection in 2017 at the age of approximately three and a half.