False Killer Whale


Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus: Pseudorca
Species: crassidens
Common names: False killer whale; Pseudorca; Blackfish
Irish Name: An chráin dhubh bhréige

Key Identification Features

Maximum body length: 6m (19ft 9in)
Average body length: 5.5m (18ft)
Head Shape: Slender head that tapers.
Beak: Rounded snout that overhangs the lower jaw. Above the mouth-line a crease trails below the eye to the top of the head.
Dorsal fin: Tall curved dorsal fin, can be found halfway along the rounded body.
Pectoral fin: Different to many other whales in that they have a unique elbow like that of the long finned pilot whale. This is identified by a broad hump on the leading edge, which resembles a shoulder
Colouration: Dark body colour, predominantly black, save for the odd faint grey marks on the head and throat and sometimes on the underside.
Markings: They quite often have scars on various parts of their bodies

Field Identification

The false killer whale is smaller than the killer whale and larger than other dolphin species. They have a streamlined body, small head with a large rounded beak. They have a dark coloration and a prominent dorsal fin. They are fast and active swimmers, preferring deep waters. The False killer whale is the only “Blackfish” to bow ride and swim rapidly at the surface.

Species Similar in Appearance

Can be confused with pilot and killer whales.


Little is known about them in the wild, due to their scarcity. Mass stranding of this species do occur and one documented case sites a mass stranding of over 800 individuals. Like killer whales, false killers are inquisitive, often approaching boats. They are known to bow-ride or wake ride.

A fast swimming species, they are quick and agile and execute high leaps and make rapid turns and sudden stops when feeding. They often lift their heads and much of their bodies out of the water when they surface, sometimes with the mouths open displaying rows of teeth. The following behaviours are common:

  • Breaching: Leaping completely out of the water · Lob tailing: Lying at the surface, slapping flukes up and down in the water
  • Bow riding: Swimming alongside fast moving boats

Status and Distribution

“The false killer whale was first known from a skeleton from Lincolnshire, England, where it was named Phocaena crassidens. A mass stranding in 1860 proved its continued existence, which had been in doubt. After examining the mammal a Danish zoologist Johannes Reinhardt changed the classification to Pseudorca crassidens. He referred to this cetacean's resemblance to the killer whale. The specific name crassidens, means ‘thick-tooth' as a reference to this species' robust teeth.”

Although widely distributed, they are not abundant anywhere. They seem to prefer deep, offshore, warm or temperate waters in either semi-enclosed seas or open-ocean. The false killer whale is considered “threatened”. In 1992 the IWC scientific committee were unable to determine their status due to lack of information on stock identification.

Where and When Best Seen in Ireland

This species is best seen at sea or in open water. An unconfirmed sighting in Galway Bay was made in 1971, but last summer (2001) the first confirmed sighting was made off the west coast on the SIAR survey. This is a species which may be seen more frequently in the future.

Food and Feeding

Much of the excited activity associated with this species is related to their feeding habits. They prefer squid and a large variety of fish found in deep offshore waters. False killer whales have a reputation for taking fish from fisherman's long lines, and have even been know to attack dolphins escaping tuna nets in the eastern tropical Pacific.

Reproduction and Life Cycle

Max life expectancy:63 years
Male longevity: 58 years
Female sexual maturity: Females have a significant post reproductive lifetime.
Reproduction rate: Low productive rate, with a 7 year interval between births.

Social Structure

False killer whales live in tight pods, and a typical extended family unit may contain 10-50 individuals, comprising males and females of all ages. However, due to their complex social nature, gatherings of groups containing several hundred can occur. False killer whales have been known to socialise with bottlenose dolphins.

Conservation Issues

Localised drive fisheries in Japan. Live capture for the display industry, to which they seem to be well adapted. Interactions with fisheries and fishing gear.

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