Orcinus orca

Killer whales live in all the oceans between the Arctic and Antarctic ice packs. Given this enormous range and their predatory lifestyle, it is not surprising that they are adaptable, with excellent memory, intelligence, and a capacity for social complexity. They tend to live in pods of fewer than 10 animals, built around a stable core of 2-3 generations of related females - mothers, daughters, sisters, and aunts. This is shown by genetic studies of pods living in the same area. Adult females without calves, and adult males, may help care for and train younger whales to hunt, especially when a reproducing female is rearing more than one offspring. Cooperation extends to hunting, and these animals are known to attack and drown larger whales by swarming them from all sides. Orcas may even beach themselves temporarily to snatch seals, or knock them off ice floes by ramming the ice. Their prey includes larger marine mammals, fish, birds, and cephalopods.

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account

Orcas are the top predator in the sea and have an extremely broad diet, including fish, gulls, penguins, turtles, squid and marine mammals, even including large whales such as grey and blue whales (2). They spend their life in stable groups, called pods (2), which hunt co-operatively (6). Long-term studies off Canada have shown that orcas occur as 'transient', 'resident' or 'offshore' populations, which have different hunting styles and social organisation (4). Orcas are extremely active and acrobatic; they are one of the fastest animals in the sea and often breach (clear the water), lobtail (slap the tail flukes on the surface of the water), and spy-hop (bring the head out of the water) (4). Females become sexually mature in their teens and produce a single calf every three years until they reach around 40 years of age (6). After the gestation period of up to 17 months, calves are suckled for about a year (6). Killer whales live to between 50 and 100 years of age (6).

The orca, once also known as the killer whale, is in fact the largest of the dolphins (2). They are easily identified by the black and white colouration; the underside is white and there are white patches behind the eyes, and a greyish white area called a 'saddle-patch' behind the dorsal fin (2). The shape of the saddle is unique in each animal, and can help to identify individuals (4). The dorsal fin is also used to recognise individuals (4). Male orcas have the tallest dorsal fin known in the animal kingdom (4), measuring up to six feet high in mature males (2), it can be as tall as a man (4). Females have shorter, more curved dorsal fins (4).

Orcinus orca is found living in all oceans of the world. They have been spotted from as far north as the Artic Ocean near pack ice to as far south as the Antarctic Ocean. Although Orcinus orca seems to prefer colder waters, they have also been observed in tropical waters. There seems to be no or very little migration due to weather and water temperature, but killer whales will move to other areas when food becomes scarce.

Biogeographic Regions: arctic ocean ; indian ocean; atlantic ocean ; pacific ocean

Other Geographic Terms: cosmopolitan

Antarctica/Southern Ocean; East Pacific; Eastern Atlantic Ocean; Indo-West Pacific; Western Atlantic Ocean

cosmopolitan

Red Sea.

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Throughout the world's oceans and seas, from high latitudes to the equator; most common in cooler coastal waters of both hemispheres, with the greatest abundance within 800 km from continental coasts.

Historic Range:
Southern Resident DPS, which consists of whales from the J, K, and L pods, wherever they are found in the wild.

Cosmopolitan; found in all oceans.

Cosmopolitan; found in all oceans.

Found in every ocean, the orca is one of the most widely distributed animals known (2). In the UK, it occurs most often around northern and western Scotland, and closer to shore between May and October (3).

Killer whales have streamlined, black and white bodies. They are black on the dorsal surface, white extends from the bottom of the chin to just beyond the anus on the ventral surface. There is also a white spot above the eye. In both sexes there is a "saddle spot" which is a grey spot behind the dorsal fin on the back. In calves, their black is somewhat grey up to a year old. Also, the white on the calf's underside has a yellow tint to it until they reach 1 year old. The average length for a male adult is 8 m, with the maximum length at 9.75 m. The average length in females is 7 m with a maximum length of 8.5 m. Newborn calves are from 2 to 2.4 m long and weigh about 136 kg at birth. The average weight for a male killer whale is 7200 kg. Female average body size and weight is slightly smaller than that of males. In males, the erect dorsal fin can reach up to 1.8 m high; in females and immature males this dorsal fin is only about 0.9 m high. This fin curves over either to the right or left side.

Average mass: 7200 kg.

Range length: 9.75 (high) m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Average mass: 3.9875e+06 g.

Length: 9100 cm

Killer whales live in aquatic marine habitats. They are found in all oceans of the world. Normally prefering depths of 20 to 60 m, killer whales also visit shallow waters along coastlines or dive to 300 m in search of food. Killer whales generally occupy the same home range year round.

Range depth: 20 to 300 m.

Average depth: 60 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: pelagic ; coastal

inshore and offshore

Depth range based on 1405 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1093 samples.

Environmental ranges
  Depth range (m): 0 - 2450
  Temperature range (°C): -1.693 - 29.197
  Nitrate (umol/L): 0.042 - 30.376
  Salinity (PPS): 27.525 - 36.842
  Oxygen (ml/l): 4.513 - 8.967
  Phosphate (umol/l): 0.053 - 2.135
  Silicate (umol/l): 0.787 - 83.019

Graphical representation

Depth range (m): 0 - 2450

Temperature range (°C): -1.693 - 29.197

Nitrate (umol/L): 0.042 - 30.376

Salinity (PPS): 27.525 - 36.842

Oxygen (ml/l): 4.513 - 8.967

Phosphate (umol/l): 0.053 - 2.135

Silicate (umol/l): 0.787 - 83.019
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Marine

Comments: Mainly in coastal waters, but may occur anywhere in all oceans and major seas at any time of year.

Cold and warm marine waters worldwide.

The orca inhabits both coastal and offshore waters (5). It has also been known to venture into estuaries (5).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Migratory in some regions, nonmigratory in other regions. Migrations apparently are related to movements of prey species.

The longest known movement involved three individuals photographed in Glacier Bay, Alaska, on 6 August 1989, and subsequently observed attacking gray whales in Monterey Bay, California, on 2 May 1992 (Goley and Straley 1994); whether this movement was transitory or migratory is unknown.

Killer whales are exceptionally successful predators. Orcinus orca diet is difficult to study and is most frequently assessed through looking at stomach contents. They eat a wide variety of large prey including: seals, sea lions, smaller whales and dolphins, fish, sharks, squid, octopi, sea turtles, sea birds, sea otters, river otters, and other animals.  Killer whales eat on average 45 kg of food a day, but they can eat much more than that. They swallow small prey whole, but tend to tear up larger prey before consumption. Killer whales are social hunters, as are wolves and lions. They often hunt in packs and use coordinated social behavior and communication to hunt prey larger than themselves, such as larger whales.

Animal Foods: birds; mammals; reptiles; fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Molluscivore )

Comments: Opportunistic; diet differs seasonally and geographically. Eats marine mammals (seals, dolphins, occasionally baleen whales), birds, fishes, and squid. May hunt cooperatively. Off Washington, British Columbia, and Alaska, "transients" feed mainly on pinnipeds, "residents" feed primarily on salmon (Baird et al. 1992).

Killer whales are top predators in most marine ecosystems and impact the populations of common prey, such as seals and sea lions in breeding areas. Killer whales are host to some endoparasites and ectoparasites. They are host to killer whale lice (Cyamus orcini), trematodes (Fasciola skiranini), cestodes (Trigonocotyle spasskyi), and nematodes (Anasakis simplex).

A disease that affects killer whales and is often studied is toxoplasmosis (Toxoplasma gondii). While this parasite is often benign, it can have serious and fatal effects.

Commensal/Parasitic Species:

• killer whale lice (Cyamus orcini)
• trematodes (Fasciola skirabini)
• cestodes (Trigonocotyle fasciola)
• nematodes (Anasakis simplex)

Killer whales have no natural predators, although young killer whales may be attacked by other killer whales or large sharks. They are at the top of the marine food chain. Humans sometimes prey on killer whales, but not in great numbers.

Orcinus orca preys on:
Boreogadus saida
Vertebrata
Phoca groenlandica
Phoca
Phoca hispida
Oncorhynchus tshawytscha
Lagenorhynchus cruciger
Mesoplodon europaeus
Mesoplodon layardii
Balaena mysticetus
Eubalaena glacialis
Enhydra lutris
Zalophus californianus
Callorhinus ursinus
Arctocephalus australis
Arctocephalus philippii
Phoca largha
Mirounga angustirostris

Based on studies in:
Arctic (Marine)

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: No exact figures.

Travels in well-defined social groups (pods), usually of fewer than 40 (averaging less than 10); sometimes forms aggregations exceeding 100. Studies in Puget Sound indicate strong social bonds and stable group structure. Typical pod contains mature females and their young (1-3 juveniles per female) and variable proportions of of males and/or post-reproductive females.

There are 3 categories of vocalizations used by killer whales: whistles, discrete calls, and clicks. Vocalizations are used both for communication and navigation. They use discrete calls and whistles when communicating within and among pods. Each pod has their a discrete dialect that sounds slightly different from that of other pods. This dialect has been shown to stay the same in a pod for up to six generations. Clicks seem to be used only for echolocation. Killer whales do have good vision, but in dark water their vision is not helpful in catching prey or navigating. As in other toothed whales, killer whales use sonar to perceive their aquatic environment.

The whale's ears are very small openings behind the eyes, which have no outer flap. The killer whale hears the whistles and clicks through an auditory bulla (earbone complex) in its lower jaw. The sound waves enter through the jaw where they then enter into the earbone complex. In this auditory bulla, there are bones that are like the bones found in the human ear. They waves travel trough these bones, then enter into the brain via an auditory nerve.

Communication Channels: visual ; acoustic

Perception Channels: visual ; acoustic ; echolocation

Comments: Active day and night.

Killer whale mortality rate varies with the age of the animal. Neonatal mortality is very high, in captivity neonatal mortality is between 37% and 50%. The reason for these high mortality rates is unknown, but predation is not considered a primary threat during this time. After six months, mortality rates steadily decline as killer whales learn how to protect and nourish themselves. Mortality rates are said to be the lowest around 12 to 13 years in males and 20 years in females.  The average lifespan for a female in the wild is around 63 years, with a maximum of 80 to 90 years. Male life expectancy is a bit shorter, with the average lifespan being around 36 years, with a maximum of 50 to 60 years.

Range lifespan
Status: wild: 90 (females) 60 (males) (high) years.

Typical lifespan
Status: wild: 63 (females) 36 (males) (high) years.

Killer whales are polygynandrous; both males and females have multiple mates throughout a season or a lifetime.

Mating System: polygynandrous (promiscuous) ; cooperative breeder

While killer whales are difficult to study in the wild some of their reproductive habits have been recorded and studied in captive whales. Killer whales can reproduce whenever females enter estrus, which can occur mutiple times a year. However, most breeding happens in the summer, and killer whales are typically born in the fall. Females reach sexual maturity between 6 and 10 years of age. Males reach sexual maturity between 10 and 13 years old. Female killer whales begin to mate between 14 and 15 years of age. The youngest female whale on record to give birth was 11 years old. Females have a calf every 6 to 10 years and they stop breeding around the age of 40. The result is 4 to 6 offspring over a 25 year span.

Gestation takes about 14 months, although a gestation length in captivity was recorded at 539 days. Killer whales have a single calf at a time, twins have only been recorded once. Newborn calves nurse for about a year before weaning. Some studies show that almost half of all newborn calves die before their first birthday.

Breeding interval: Females breed every 3 to 10 years.

Breeding season: Breeding can occur at any time of the year, most often in the summer.

Range number of offspring: 1 (low) .

Average number of offspring: 1.

Range gestation period: 12 to 18 months.

Average birth mass: 181 kg.

Range weaning age: 12 to 24 months.

Range age at sexual or reproductive maturity (female): 6 to 10 years.

Range age at sexual or reproductive maturity (male): 10 to 13 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 180000 g.

Average number of offspring: 1.

Killer whale females invest a lot of energy in raising their offspring. They carry the calf for almost a year and a half, then give birth and nurse for another 12 months. During that time, mothers teach their calves to hunt and include their offspring in the social network of their pods. Because these animals are not monogamous, it is assumed that the fathers exhibit no parental involvement after mating. When a killer whale calf is born into a pod, it relies on its mother for nutrition and support. Calves remain in their natal pod after independence.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning

Mating occurs late fall to midwinter in the northeastern Atlantic. Gestation lasts about 17 months (IUCN 1991). Litter size is 1. Calf may be dependent for at least 2 years, closely associated with mother for much of juvenile period. Calving interval has been estimated at 3-8 years (higher estimates may be more typical). Sexually mature at 10-18 years. Females become reproductively senescent at 35-45 years. Estimated maximum age 80-90 years in females, 50-60 years in males.

Recent genetic evidence suggests that there may in fact be three different species instead of a single Orcinus orca. These three species correspond to ecotypes, which had already been recognized as having differences in size and color pattern, behavior, prey preference, and social organization.

Researchers sequenced mitochondrial genomes of 143 orcas and three outgroup species (false killer whale, long-finned pilot whale and short-finned pilot whale). They found 66 orca hapolotypes which clustered geographically and by ecotype. They estimate that the clades diverged between 150,000 and 700,000 years ago, with two Pacific clades splitting first and then an Atlantic clade more recently.

According to the IUCN red list there is insufficient data about killer whale populations to assess their status. The data on the endangered species act list states that killer whales are endangered. They are on Appendix II of the CITES site, which means they are not threatened by extinction, but conservation efforts must be employed to help keep them from moving closer to extinction. Killer whales have not been as directly impacted by human exploitation as other whale species. They are occasionally hunted but management of harvests seems to have been effective.

US Federal List: endangered

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: data deficient

Accidental?

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Cosmopolitan in oceans; abundance and trends are not well known.

There is no longer a fishery devoted solely to Killer whales, but they are still hunted commercially in some areas. Listed in CITES Appendix II. Protected since 1980 by IWC moratorium against factory ship whaling.

There is no longer a fishery devoted solely to Killer whales, but they are still hunted commercially in some areas. Listed in CITES Appendix II. Protected since 1980 by IWC moratorium against factory ship whaling.

Classified as Data Deficient (DD) on the IUCN Red List (1). Listed on Annex IV of the EC Habitats Directive; eastern North Atlantic populations and eastern North Pacific populations of orca are listed under Appendix II of the Bonn Convention (also known as the Convention on Migratory Species, or CMS) and Appendix II of the Bern Convention (7). All cetaceans (whales and dolphins) are listed on Annex A of EU Council Regulation 338/97; they are therefore treated by the EU as if they are included in CITES Appendix I, so that commercial trade is prohibited. In the UK all cetaceans are fully protected under the Wildlife and Countryside Act, 1981 and the Wildlife (Northern Ireland) Order, 1985 (3).

Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses

The orca is threatened by hunting, prey depletion, and exposure to human activities such as disturbance from boats including whale-watching crafts, particularly when they venture closer to shore (3). As it is the top predator it is particularly vulnerable to contaminants, which build up in the tissues of prey species and subsequently affect the predator (6). Furthermore, the captivity industry has posed a threat, taking live individuals for the aquarium trade (2).

Biological Research Needs: Worldwide taxonomic review to determine subspecific status.

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Populations occur in "protected" waters of Washington, British Columbia, and Alaska; also protected by the Marine Mammals Protection Act. See IUCN (1991) for a brief discussion of international and national protection regulations.

Needs: Worldwide ban on hunting.

The orca is a UK Biodiversity Action Plan priority species (3). It is protected in UK waters by the Wildlife and Countryside Act 1981 and the Wildlife (Northern Ireland) Orders 1985; it is illegal to intentionally kill, injure, or harass any cetacean (whale or dolphin) species in UK waters (3). The Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas (ASCOBANS) has been signed by seven European countries, including the UK. Provision is made under this agreement to set up protected areas, promote research and monitoring, pollution control and increase public awareness (3).

There are no known adverse effects of Orcinus orca on humans.

Killer whales are hunted and used for a number of things. In various parts of the world, they are used for oil and meat. Meat is sold for human consumption or used for fertilizer or bait.

Positive Impacts: food ; body parts are source of valuable material

Comments: Current primary use: public display in marine aquaria, where generally long-lived and popular. Taken in local cetacean fisheries in various parts of the range; used for human food, animal food, and as source of oil (IUCN 1991). In some areas, regarded by fishermen as a nuisance due to destruction of fishes and fishing gear (see examples in IUCN 1991).

Data Deficient (DD)