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Brief Summary

    Killer whale: Brief Summary
    provided by wikipedia
    "Orca" redirects here. For other uses, see Orca (disambiguation). For The Avengers episode, see Killer Whale (The Avengers).

    The largest living species of dolphin

    The killer whale or orca (Orcinus orca) is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as seals and dolphins. They have been known to attack baleen whale calves, and even adult whales. Killer whales are apex predators, as no animal preys on them. A cosmopolitan species, they can be found in each of the world's oceans in a variety of marine environments, from Arctic and Antarctic regions to tropical seas, absent only from the Baltic and Black seas, and some areas of the Arctic Ocean.

    Killer whales are highly social; some populations are composed of matrilineal family groups (pods) which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviours, which are often specific to a particular group and passed across generations, have been described as manifestations of animal culture.

    The International Union for Conservation of Nature assesses the orca's conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with human fisheries. In late 2005, the southern resident killer whales, which swim in British Columbia and Washington state waters, were placed on the U.S. Endangered Species list.

    Wild killer whales are not considered a threat to humans, but there have been cases of captive orcas killing or injuring their handlers at marine theme parks. Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers.

    MammalMAP: Orcas
    provided by EOL authors

    The wordOrcinusis derived fromOrcus– the mythological Roman god of the netherworld.This is probably due to its fierce reputation as the ‘wolves of the sea’ as they are known to hunt other ocean mammals.

    Orcas hunt in family groups, calledpods, of up to 40 members using cooperative hunting strategies.Different pods target different prey.Resident pods tend to prefer fish while transient pods tend to target marine mammals.Polar bears, birds, squids, even a moose has been recorded by analysing the stomach contents of orcas.

    There are 3 recognised categories ofvocalizationsused by killer whales: clicks, whistles and discrete calls.While clicks seem to be used solely for echolocation, whistles and discrete call are used when communicating within and among pods.Each pod has their own dialect that sounds different from other pods.This dialect tends to stay the same in a pod for up tosix generations.

    TheIUCN Red listclassifies orcas as a data deficit species – as further study is needed to determine whether there are more than one species of orca.

    For more information on MammalMAP, visit the MammalMAPvirtual museumorblog.

    Orca
    provided by EOL authors
    Although Orcas are known as fierce predators of the sea, it is also known that some Orcas are non mammal eating predators, and have also been seen swimming with dolphin packs.
    Brief Summary
    provided by Ecomare
    Orcas, also called killer whales, are the largest member of the dolphin family. They often hunt in groups, driving a school of fish together and chasing them to the surface. They sometimes patrol along shores, for example when hunting seals. They will even throw themselves onto the shore in order to grab their prey. That is a risky business for orcas: if they beach too far, there is a possibility that they can't get back into the water. A group of orcas lives in the northern part of the North Sea, around the Shetland and Orkney Islands.
    Brief Summary
    provided by FAO species catalogs
    Studies in the eastern North Pacific, from Washington State to Alaska, have distinguished 2 types of killer whales, referred to as residents and transients. Although differentiated by ecological differences, there are also differences in coloration and external morphology. In Washington and British Columbia, at least, residents are primarily fish eaters and transients eat mostly marine mammals. Some studies in other parts of the world suggest that this pattern may be universal. Pods of resident killer whales in British Columbia and Washington represent one of the most stable societies known among non-human mammals; individuals stay in their natal pod throughout life. Differences in dialects among sympatric groups appear to help maintain pod discreteness. Most pods contain 1 up to 55 whales and resident pods tend to be larger than those of transients. In the Pacific Northwest, calving occurs in non-summer months, from October to March. Similarly, in the northeast Atlantic, it occurs from late autumn to mid-winter.

    Though best known for their habits of preying on warm-blooded animals (killer whales are known to have attacked marine mammals of all groups, from sea otters to blue whales, except river dolphins and manatees), killer whales often eat various species of fish and cephalopods. Killer whales also occasionally eat seabirds and marine turtles.

Comprehensive Description

Distribution

    Distribution
    provided by World Register of Marine Species
    cosmopolitan
    Distribution
    provided by World Register of Marine Species
    Antarctica/Southern Ocean; East Pacific; Eastern Atlantic Ocean; Indo-West Pacific; Western Atlantic Ocean
    Distribution in Egypt
    provided by Bibliotheca Alexandrina LifeDesk

    Red Sea.

    Distribution
    provided by Animal Diversity Web

    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

Morphology

    Morphology
    provided by Animal Diversity Web

    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.

Size

Diagnostic Description

    Diagnostic Description
    provided by FAO species catalogs
    Killer whales are among the most distinctive, and therefore easily identified, of all cetaceans. The tall erect dorsal fin is nearly as distinctive as the colour pattern. It may reach 0.9 m in females and 1.8 m in males. Adult males tend to have dorsal fins that are triangular or that may even cant forward to varying degrees. Killer whales have blunt snouts, with only very short and poorly defined beaks. The flippers are large and oval, and grow to lengths of up to 2 m in bulls.

    The black-and-white colour pattern is unmistakable. The lower jaw, undersides of the flukes, and ventral surface from the tip of the lower jaw to the urogenital area is white. White lobes extend up the sides behind the dorsal fin, and there is a white oval patch above and behind each eye. The rest of the body is black, except for a light-grey "saddle patch" behind the dorsal fin. In some populations, the dorsal coloration includes a narrow black cape, below which the dark areas are more nearly charcoal grey.

    There are 10 to 12 large, recurved teeth in each half of both jaws, which are oval in cross-section. In older animals, they are often worn and damaged by abscesses.

    Can be confused with: Killer whales are easily recognizable to almost anyone who has spent time on the water or along the coast in areas they frequent. The great size of the dorsal fin (especially of adult males) and unique black and white colour pattern are diagnostic. At a distance, groups without adult males can be confused with Risso's dolphins and false killer whales.

Habitat

    Habitat
    provided by World Register of Marine Species
    inshore and offshore
    Habitat
    provided by Animal Diversity Web

    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

Trophic Strategy

    Trophic Strategy
    provided by Animal Diversity Web

    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 )

Associations

    Associations
    provided by Animal Diversity Web

    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)
    Associations
    provided by Animal Diversity Web

    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.

Behavior

    Diet
    provided by World Register of Marine Species
    Numerous fish, squid, and marine mammal species, including blue whales; even gulls, penguins and turtles.
    Behavior
    provided by Animal Diversity Web

    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 ; tactile ; acoustic ; echolocation ; chemical

Life Expectancy

    Lifespan, longevity, and ageing
    provided by AnAge articles
    Maximum longevity: 90 years (wild) Observations: Reproductive senescence has been reported in this species and no female over the age of 48 has been observed to give birth. Maximum longevity in the wild has been estimated to be around 90 years and the MRDT was calculated to be about 14 for females (Foote 2008). Anecdotal evidence, which could be true, suggests these animals may live up to 100 years. In captivity, one wild born animal was still alive at about 37 years of age (Richard Weigl 2005).
    Life Expectancy
    provided by Animal Diversity Web

    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.

Reproduction

    Reproduction
    provided by Animal Diversity Web

    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.

    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); sexual ; 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

Evolution

    Evolution
    provided by EOL authors
    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.

Conservation Status

    Status in Egypt
    provided by Bibliotheca Alexandrina LifeDesk

    Accidental?

    Conservation Status
    provided by Animal Diversity Web

    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

Benefits

    Benefits
    provided by Animal Diversity Web

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

    Benefits
    provided by Animal Diversity Web

    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

    Benefits
    provided by FAO species catalogs
    Conservation Status : Pelagic whaling activities have rarely directed their attention towards killer whales, but whaling fleets have taken a few in most years. Very small numbers of killer whales were taken in the North Pacific by now-defunct shore whaling stations. Fishermen in many areas see killer whales as competitors, and shooting of whales is known to occur. This problem is especially serious in Alaska, where conflicts with longlines fisheries occur. Small numbers are taken incidentally in fisheries in many areas. Live captures for public display have been banned in most areas of the eastern North Pacific. Subsequently, live capture activities shifted to Iceland, but in 1991, the Icelandic government announced that once current permits for live capture expire, no new ones will be issued. IUCN:

    Insufficiently known.

Risks

    IUCN Red List Category
    provided by World Register of Marine Species
    Data Deficient (DD)

Citizen Science links

Other Articles

    Untitled
    provided by Animal Diversity Web

    The fossil history of killer whales dates to the Pliocene epoch, about 5 million years ago. The fossil history is not rich, but some finds link Orcinus orca to its early ancestors. Teeth, partial skulls, jaw bones, and periotic bones (found in a mammal's ear) have been found and identified in many countries of the world, including: Japan, Hungary, Italy, and South Africa.