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Pseudorca crassidensfalse killer whale

By Kevin Hatton

Geographic Range

Pseudorca crassidens is found throughout the Atlantic, Pacific, and Indian Oceans. It is nearly cosmopolitan, occurring at latitudes as far north as 50 degrees north and as far south as 52 degrees south.

This species has been observed as far south as New Zealand, Peru, Argentina, South Africa, and the north Indian Ocean. They also range from Australia, the Indo-Malayan Archipelago, Philippines, and north to the Yellow Sea. They have been observed in the Sea of Japan, coastal British Columbia, coastal Maryland (USA), the Bay of Biscay, and have been discovered in the Red and Mediterranean Seas. Many pods live near the Gulf of Mexico and surrounding the Hawaiian Islands. (Shirihai and Jarrett, 2006)

Habitat

False killer whales are common in tropical or temperate seas. They visit coastal waters but prefer to remain in deeper waters. They are known to dive as deep as 2000 meters. (Watson, 1981; Shirihai and Jarrett, 2006; Watson, 1981; Shirihai and Jarrett, 2006; Watson, 1981; Shirihai and Jarrett, 2006; Watson, 1981)

  • Range depth
    0 to 2000 m
    0.00 to 6561.68 ft
  • Average depth
    500 m
    1640.42 ft

Physical Description

False killer whales are black or dark gray with a white blaze on their ventral side. Some have a paler gray coloring on their head and sides. Their heads are rounded and often described as blunt and conical with a melon-shaped forehead. Their bodies are elongated. The dorsal fin is sickle-shaped and protrudes from the middle of their back, the pectoral flippers are pointed. They have a slight overbite--the upper jaw extends beyond the lower jaw. This gives them a slight beaked look to their rostrum. No subspecies have been described.

Adult males range from 3.7 to 6.1 m in length, while adult females range from 3.5 to 5 m. Adults may weigh 917 to 1842 kg. Newborns range from 1.5 to 1.9 m in length and weigh about 80 kg. The dorsal fin can grow to be 18 to 40 cm high. This species has a more slender build compared to other dolphins and they have tapering heads and flippers. Their flippers average about one-tenth of the head and body length and have a distinct hump on the leading margin of the fin. There is a definite median notch on their flukes and they are very thin with pointed tips. False killer whales also have 8 to 11 teeth on each side of their jaw.

The skulls of females range in length from 55 to 59 cm, while males are 58 to 65 cm. They have 47 to 52 vertebrae: 7 cervical, 10 thoracic, 11 lumbar, and 20 to 23 caudal vertebrae. They have 10 pairs of ribs. Their manus consists of 6 carpals, 5 metacarpals, and 14 phalanges.

This species is often mistaken for bottlenose dolphins (Tursiops truncatus), short-finned pilot whales (Globicephala macrorhynchus), or long-finned pilot whales (Globicephala melas) as they inhabit the same regions. To distinguish these species, bottlenose dolphins have beaks, and pilot whales are larger with obvious dorsal fin differences. ("Review on Small Cetaceans: Distribution, Behaviour, Migration and Threats", 2005; Liebig, et al., 2007; Minasian, et al., 1984; Nowak, 1999; Shirihai and Jarrett, 2006)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently
  • Range mass
    916.26 to 1841.59 kg
    2018.19 to 4056.37 lb
  • Range length
    3.5 to 6.1 m
    11.48 to 20.01 ft

Reproduction

Although false killer whales breed year-round, their breeding peaks in late winter to early spring. Studies suggest they are polygynandrous. (Nowak, 1999; Shirihai and Jarrett, 2006)

False killer whales will only have one calf per pregnancy and she carries that calf for 11 to 15.5 months. The calf stays with the mother for 18 to 24 months. Between 18 and 24 months old, the calf is gradually weaned. Sexual maturity occurs in females between 8 and 11 years of age and in males at 8 to 10 years.

In this species and a few others in the family Didelphinidae, if the female doesn't conceive after the first ovulation, she will keep ovulating until she does conceive. After giving birth, the female will not breed again for an average of 6.9 years. (Perrin, et al., 2002; Shirihai and Jarrett, 2006; Slijper, 1962)

  • Breeding interval
    Females give birth every 6.9 years, on average.
  • Breeding season
    Breeding occurs year-round, but peaks December to January and again in March.
  • Range number of offspring
    1 (high)
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    11 to 15.5 months
  • Range weaning age
    18 to 24 months
  • Range age at sexual or reproductive maturity (female)
    8 to 11 years
  • Range age at sexual or reproductive maturity (male)
    8 to 10 years

After false killer whales calves are born, they are cared for and nursed by their mother for up to 24 months. Young are capable of swimming on their own shortly after birth. Young are likely to remain in the same social group with their mother beyond weaning. (Nowak, 1999; Slijper, 1962)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents
  • extended period of juvenile learning

Lifespan/Longevity

Researchers estimate that males live an average of 57.5 years and females live an average of 62.5 years in the wild. No known age-dependent mortality rate has been discovered. Because few false killer whales are kept in captivity, captive lifespans are unknown. (Shirihai and Jarrett, 2006; Stacey, et al., 1994)

Behavior

False killer whales are found in groups ranging from just a few individuals to hundreds of individuals. In these large groups they are sometimes separated into smaller groups or pods, which average about 18 members (typically 10 to 30). Pods consist of all ages and both sexes.

False killer whales often "strand" themselves in large numbers. Large strandings have been reported on beaches in Scotland, Ceylon, Zanzibar and along the coasts of Britain. It is thought that stranded groups might have been chasing groups of seals or sea lions into the shallower waters and became stuck.

It has been said that false killer whales are as social as pilot whales (Globicephala). They ride in the wakes and bow waves of ships. They prefer faster-moving ships, but will ride the bow waves on any vessel. They are one of the few large mammals that leap out of the water over the wake of the ship, which is a useful identification attribute. (Liebig, et al., 2007; Perrin, et al., 2002; Shirihai and Jarrett, 2006; Slijper, 1962; Watson, 1981)

Home Range

This species is not restricted to known home ranges.

Communication and Perception

Pseudorca crassidens use echolocation primarily in the frequency range of 20 yo 60 kHz. They also use higher frequencies of 100 to 130 kHz. False killer whales, like other toothed whales also use other sounds, such as whistles, squeals, or less distinct pulsating sounds. It has been noted that whenever researchers get close to a group of false killer whales, they have been able to detect the whales' piercing whistles from about 200 meters away. James Porter notes, "The noises were astonishingly diverse, much more varied than the sounds of human speech, both in pitch and intensity. Each whale seemed to be making different sounds. The cacophony gave the impression that whatever they were 'saying', they were not all 'saying' the same thing at the same time (Watson 1981)." (Perrin, et al., 2002; Watson, 1981)

Food Habits

False killer whales are carnivores, eating primarily fish and squid. They mainly eat squid (Loligo) but also opportunistically take fish and occasional marine mammals, such as seals (Phocidae) or sea lions (Otariidae). Some of the fish they eat include salmon (Oncorhynchus), squid (Loligo, Berryteuthis magister, or Gonatopsis borealis), sciaenid and carangid fishes, bonito (Sarda lineolata), mahi mahi (Coryphaena hippurus), yellowfin tuna (Thunnus albacares), yellowtail (Pseudosciana manchurica), and perch (Lateolabrax japonicus). On one occasion researchers found the remains of a humpback whale Megaptera noveangliae in the stomach of a false killer whale.

This species moves quickly in order to catch fish. They have been observed catching a fish in their mouth while completely breaching the waters' surface. They have also been seen shaking their prey until the head and entrails are shaken off. They then peel the fish using their teeth and discard all the skin before eating the remains. Some mothers will hold a fish in the mouth and allow their calf to feed on the fish. This food manipulation is rare in cetaceans. ("Review on Small Cetaceans: Distribution, Behaviour, Migration and Threats", 2005; Perrin, et al., 2002; Watson, 1981)

  • Animal Foods
  • mammals
  • fish
  • mollusks
  • other marine invertebrates

Predation

Due to their harmful effects on fisheries, humans kill false killer whales. In some regions in the eastern tropical Pacific, they are hunted for meat. (Nowak, 1999; Slijper, 1962)

Ecosystem Roles

False killer whales are predators of fish and squid (Uroteuthis duvauceli), and they also eat smaller delphinids and pinnipeds (e.g., seals [Phocidae], and sea lions [Otariidae]).

One protozoan that is found in false killer whales are the parasites Bolbosoma capitatum. They are also carriers of two types of whale lice: Lsocyamus delphini and Cyamus antarcticensis. (Perrin, et al., 2002)

Commensal/Parasitic Species
  • Lsocyamus delphini
  • Cyamus antarcticensis
  • Bolbosoma capitatum

Economic Importance for Humans: Positive

In the eastern tropical Pacific, Pseudorca crassidens is taken for food and also to limit their consumption of tuna Osteoglossiformes and inhibit their competition with commercial fisheries. (Nowak, 1999)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

These whales will eat fish off of fishing lines and out of nets of commercial fishing operations. (Nowak, 1999; Perrin, et al., 2002)

Conservation Status

Although false killer whales are hunted by humans and there are annual mass strandings, populations are considered stable. There are only a few countries that hunt them for food or remove them as threats to the fisheries industry. (Nowak, 1999)

Other Comments

This species was thought to be extinct until approximately 50 years ago, because only skulls and other bones washed ashore. (Shirihai and Jarrett, 2006)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Kevin Hatton (author), Radford University, Karen Powers (editor, instructor), Radford University.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

induced ovulation

ovulation is stimulated by the act of copulation (does not occur spontaneously)

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

Convention of Migratory Species. Review on Small Cetaceans: Distribution, Behaviour, Migration and Threats. None. Germany: Boris Michael Culik, Marco Barbieri. 2005. Accessed September 20, 2007 at http://www.cms.int/reports/small_cetaceans/data/P_crassidens/p_crassidens.htm.

Liebig, P., K. Flessa, T. Taylor. 2007. Taphonomic Variation Despite Catastrophic Mortality: Analysis of a Mass Stranding of False Killer Whales(Pseudorca crassidens), Gulf of California, Mexico. Palaios, Volume 22, Issue 4: 384-391.

Minasian, S., K. Balcomb, III, L. Foster. 1984. The World's Whales. New York and London: W.W. Norton & Company.

Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: The John Hopkins University Press.

Perrin, W., B. Würsig, J. Thewissen. 2002. Encyclopedia of Marine Mammals. United States of America: Academic Press.

Shirai, K., T. Saki. 1997. Haematological Findings in Captive Dolphins and Whales. Australian Veterinary Journal, 75/7: 512-514. Accessed October 18, 2007 at http://www.ava.com.au/avj/jul97/512.htm.

Shirihai, H., B. Jarrett. 2006. Whales, Dolphins and Other Marine Mammals of the World. Princeton and Oxford: Princeton University Press.

Slijper, E. 1962. Whales. New York: Basic Books Inc..

Stacey, P., S. Leatherwood, R. Baird. 1994. Pseudorca crassidens. Mammalian Species, 456: 1-6.

Watson, L. 1981. Sea Guide To Whales of the World. New York, NY: Elsevier-Duton Publishing Co Inc.

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