Orca

For other uses, see Orca (disambiguation).

Orca Temporal range: Early Pliocene - Recent
Orcas near Unimak Island, eastern Aleutian Islands, Alaska
Size comparison against an average human
Conservation status
Conservation Dependent
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Superorder:	Cetartiodactyla
Order:	Cetacea
Suborder:	Odontoceti
Family:	Delphinidae
Genus:	Orcinus
Species:	O. orca
Binomial name
Orcinus orca Linnaeus, 1758
Orca range (in blue)

The Orca or Killer Whale (Orcinus orca) is the largest species of the oceanic dolphin family (Delphinidae). It is the second-most widely distributed mammal on Earth (after humans) and is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas. Orcas are highly social and generally travel in stable, matrilineal family groups.

Orcas are versatile predators, with some populations feeding mostly on fish and others on other marine mammals, including large whales. Wild orcas are usually not considered a threat to humans. There have, however, been isolated reports of captive orcas attacking their handlers at marine theme parks

Taxonomy and evolution

The orca is the sole species in the genus Orcinus. It is one of thirty-five species in the dolphin family. Like the Sperm Whale genus Physeter, Orcinus is a genus with a single, abundant species with no immediate relatives from a cladistic point of view, thus paleontologists believe that the orca is a prime candidate to have an anagenetic evolutionary history — that is the evolution of ancestral to descendant species without splitting of the lineage. If true, this would make the orca one of the oldest dolphin species, although it is unlikely to be as old as the family itself, which is known to date back at least five million years.

However, there are at least three types of orcas that are genetically distinct enough to be considered different subspecies or races. These classifications are based mostly on research performed off the west coast of Canada and the United States.

The three types are:

• Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. The resident orcas' diet consists primarily of fish and sometimes squid and they live in complex and cohesive family groups known as pods. Female residents characteristically have a rounded dorsal fin tip that terminates in a sharp corner. They are known to visit certain areas consistently.The resident orcas do travel but stay roughly in the same sector.
• Transient: The diet of these orcas consists almost exclusively of marine mammals. They do not eat fish. Transients generally travel in small groups, usually of two to six animals. Unlike residents, transients may not always stay together as a family unit. Female transients are characterized by dorsal fins that are more triangular and pointed than those of residents. Transients travel on extremely unpredictable routes ;they may be seen once in an area and never be seen after,or return 10 years later.
• Offshore: These orcas cruise the open oceans and feed primarily on fish, sharks and turtles. They have been seen traveling in groups of up to 60 animals. Currently there is little known about the habits of this population, but they can be distinguished genetically from the residents and transients. Female offshores are characterized by dorsal fin tips that are continuously rounded. Offshores also seem smaller than the 2 other types.

Transient and resident orcas live in the same areas but seem to avoid each other. The name "transient" originated from the belief that these whales, which are often seen in groups of three or four, were outcasts from larger resident pods. Researchers later discovered that transients are an entirely different community. Recent genetic research has found that the types have not interbred for up to 10,000 years.

The orca skull.

An additional two or three orca types have recently been documented in the Antarctic. Type A looks like a typical orca, living in open water and feeding mostly on minke whales. Type B and type C whales are smaller than type A. Both B and C types have grayish and light yellow skin in place of the usual black and white orca colouring; B and C types can also be distinguished from each other through variations in colour pattern. They live close to the Antarctic ice pack, with type B whales feeding mostly on seals, and type C on fish. But because the load of information is so poor and the searchers haven't really studied them,they are not officially considered as a orca type.

Physical characteristics

Dorsal fin and saddle patch of an orca in the northeast Pacific, most likely a resident female

Orcas are distinctively marked, with a black back, white chest and sides, and a white patch above and behind the eye. They have a heavy and stocky body and a large dorsal fin with a dark gray "saddle patch" at the fin's rear. Males can be up to 9.5 m long (31 ft) and weigh in excess of 6 tons; it has been reported that especially large males have reached nearer 8 tons. Females are smaller, reaching up to 8.5 m (28 ft) and a weight of about 5 tons. The longest orca ever recorded was a male from Washington state, measuring 9.8 m (32 ft). Calves at birth weigh about 180 kg and are about 2.4 m long (8 ft). The orca's large size and strength make them one of the fastest marine mammals, often reaching speeds in excess of 56 km/h (35mph).

Unlike most dolphins, the pectoral fin of an orca is large and rounded — more of a paddle than other dolphin species. Males have significantly larger pectoral fins than females. At about 1.8 m (6 ft), the dorsal fin of the male is more than twice the size of the female's, and is more of a triangle shape — a tall, elongated isosceles triangle, whereas the dorsal fin of the female is shorter and generally more curved.

Adult male orcas are very distinctive and are unlikely to be confused with any other sea creature. When seen from a distance in temperate waters, females and juveniles can be confused with various other species, such as the false killer whale or Risso's dolphin.

A female and her calf

Most life history data about orcas has been obtained from long-term surveys of the population off the coasts of British Columbia and Washington and by monitoring captive orcas. In the 1970's, researchers discovered that individual orcas could be identified from a good photograph of the animal's dorsal fin and saddle patch when it surfaces. Orcas are distinguished through variations such as nicks, scratches, and tears on the dorsal fin, and by the pattern of white or grey in the saddle patch. Photo-identification has enabled the local population of orcas to be counted each year rather than estimated, and has enabled great insight into orca lifecycles and social structures. Due to the completeness of the study and highly structured nature of the pods in this population, the information is detailed and accurate; however, transient groups and groups in other oceans may have slightly different characteristics.

Additionally, orcas are well known for their mental capabilities. Studies have indicated that an orca has an outstanding memory, perhaps even photographic. In tests conducted with orcas in captivity, they recalled testing patterns up to 25 years after they were initially conducted.

Lifecycle

Females become sexually mature at around 15 years of age. From then they have periods of polyestrous cycling with non-cycling periods of between three and sixteen months. The gestation period varies from fifteen to eighteen months. Mothers calve, with a single offspring, about once every five years. In analysed resident pods, birth occurs at any time of year, with the most popular months being those in winter. Newborn mortality is very high — one survey suggested that nearly half of all calves fail to reach the age of six months. Calves nurse for up to two years, but will start to take solid food at about twelve months. Cows breed until the age of 40, meaning that on average they raise five offspring. Typically, females live to the age of fifty, but may survive well into their eighties or nineties in exceptional cases. Males become sexually mature at the age of 15, but do not typically reproduce until age 21. Males live to about 45 on average, and close to 90 in exceptional cases.

Range

Orcas are found in all oceans and most seas, including (unusually for cetaceans) the Mediterranean and Arabian seas. However, they prefer cooler temperate and polar regions. Although sometimes spotted in deep water, coastal areas are generally preferred to pelagic environments.

The orca is particularly highly concentrated in the northeast Pacific Basin, where Canada curves into Alaska, off the coast of Iceland and off the coast of northern Norway. They are regularly sighted in Antarctic waters right up to the ice-pack and are believed to venture under the pack and survive breathing in air pockets like the beluga does. In the Arctic, however, the species is rarely seen in winter, as it does not approach the ice pack. It does visit these waters during summer.

Information for off-shore regions and tropical waters is more scarce but widespread, if not frequent, sightings indicate that the orca can survive in most water temperatures. Sightings are rare in Indonesian and Philippine waters. No estimate for the total worldwide population exists. Local estimates include 70-80,000 in the Antarctic, 8,000 in the tropical Pacific (although tropical waters are not the orca's preferred environment, the sheer size of this area — 19 million square kilometres — means there are thousands of orcas), up to 2,000 off Japan, 1,500 off the cooler northeast Pacific and 1,500 off Norway. Adding very rough estimates for unsurveyed areas, the total population could be around 100,000.

Diet

Resident (fish-eating) orcas

The orca is an apex predator, and the array of species on which orcas prey is extremely diverse. Specific populations show a high degree of specialization on particular prey species. For example, some populations in the Norwegian and Greenland sea specialise in herring and follow that fish's migratory path to the Norwegian coast each autumn. Other populations in the area prey on seals. On average, an orca eats 500 lbs. (227 kg) of food each day.

Fish and other cold-blooded prey

Fish-eating orcas prey on 30 species of fish, particularly salmon (including Chinook and Coho), herring, and tuna. Basking sharks, oceanic whitetip sharks, and occasionally even great white sharks are taken for their nutrient-rich livers. In New Zealand killer whales have been observed hunting stingrays as well. Cephalopods, such as octopuses and a wide range of squids, are also targets.

While salmon are usually hunted by a single orca or a small group of individuals, herring are often caught using carousel feeding: the orcas force the herring into a tight ball by releasing bursts of bubbles or flashing their white undersides. The orcas then slap the ball with their tail flukes, either stunning or killing up to 10-15 herring with a successful slap. The herring are then eaten one at a time. Carousel feeding has only been documented in the Norwegian orca population and with some oceanic dolphin species.

Warm-blooded prey

The orca is the only cetacean species to regularly prey on other cetaceans. Twenty-two species have been recorded as preyed on, either through an examination of stomach contents, examining scarring on the prey's body, or from observing the orcas' feeding activity. Groups of orcas will even prey on larger cetaceans such as minke whales, gray whales, and very occasionally sperm whales or blue whales. A group of orcas take a young whale by chasing it and its mother through the sea, wearing them out. Eventually the orcas manage to separate the pair and surround the young whale, preventing it from returning to the sea's surface to breathe. Whales are typically drowned in this manner. Pods of female sperm whales can sometimes protect themselves against a group of orcas by forming a protective circle around their calves with their flukes facing outwards. This formation allows them to use their powerful flukes to repel the orcas. Hunting large whales,however takes a lot of time, usually several hours.

Other marine mammals, including most species of seal and sea lion, are preyed upon by Orcas. Sea lions are killed by head-butting or by being slapped and stunned by a tail fluke. Walrus and sea otters are hunted less frequently. Several species of bird are also preyed upon, including penguins, cormorants and sea gulls.

A captive orca in Friendship Cove discovered that it could regurgitate fish onto the surface, attract sea gulls, and eat them. Other orcas then learned the behavior by example. Orcas at Sea World California have also been observed hunting birds.

There has also been one recorded case of probable orca cannibalism. A study in the South Pacific in 1975 recorded two male orcas whose stomachs contained the remains of other orcas. Of the 30 orcas captured and examined in this survey, 11 had empty stomachs — an unusually high percentage which indicates the orcas were forced to cannibalism through a lack of food.

Orcas use complex hunting strategies to find and subdue their prey. They will occasionally throw seals through the air in order to stun and kill them. Often, to avoid injury, they will disable their prey before killing and eating it. This may involve throwing it in the air, slapping it with their tails, ramming it, or breaching and landing on it.

More specialized feeding techniques are used by various populations around the world. In Patagonia, and the Iles Crozet in the Indian Ocean, orcas feed on South American sea lion and elephant seal pups in shallow water; even to the extent of purposely stranding themselves (temporarily). Orcas will spy-hop to locate seals resting on ice floes, and then create a waves, known as wave-hunting, by swimming together in groups to wash over the floe, causing the seal to be thrown into the water where a second orca waits to kill it. This behavior has only been recorded a few times and it is not known how often it occurs. The most recent recorded instance in April 2006 ended with the group of orcas actually returning the seal to the ice floe once they had shown the younger animals how to properly perform the technique.

Behavior

File:Peeking Orca.jpg

Orcas often raise their body out of the water in a behaviour called spyhopping.

The day-to-day behaviour of orcas is generally divided into four activities: foraging, travelling, resting and socializing. Orcas are generally enthusiastic in their socializing, engaging in behaviours such as breaching, spyhopping, and tail-slapping. All-male groups often interact with erect penises. Whether this interaction is part of homoerotic play or a display of dominance is not known.

Resident orcas can also be seen swimming with porpoises, other dolphins, seals, and sea lions, which are common prey for transient orcas. Resident orcas are continually on the move, sometimes traveling as much as 100 miles (160 km) in a day, but may be seen in a general area for a month or more. Range for resident orca pods may be as much as 800 miles (1300 km) or as little as 200 miles (320 km). Unlike residents, transients often travel and hunt in silence. In seas where both residents and transients inhabit, seals and sea lions can detect by their sounds if orcas are residents or transients, and this is very useful, because if it's a resident, they won't have to panic, but they will surely do if it's a transient. That's probably the reason why transients keep silent while hunting. A resident will identify itself that it is approaching the other mammal(s) by making a sound. A transient stays silent.

Social structure of resident orca communities

Fish-eating orcas in the North Pacific have a complex system of social grouping. Unlike any other mammal population whose social structure is known, resident orcas of both genders live with their mothers for their entire lives. The basic unit is the matriline, which consists of a single female (the matriarch) and her descendants. The sons and daughters of the matriarch form part of the line, as do the sons and daughters of those daughters (the sons and daughters of the sons join the matriline of their mates) and so on down the family tree.

Because females can live for up to ninety years, it is not uncommon for four or even five generations to travel together. These matrilineal groups are highly stable over many years. Individuals will only split off from their matrilineal group for up to a few hours at a time in order to mate or forage. No permanent casting out of an individual from a matriline has ever been recorded. The average matriline size as recorded in northeast Pacific waters is nine animals.

Matrilines form loose aggregations called pods, consisting on average of about 18 animals. Members of a pod all have the same dialect (see the section on vocal behaviour below) and consist of closely related matriline fragments. Unlike matrilines, pods will split apart for days or weeks at a time in order to carry out foraging before joining back together. The largest recorded pod is 49 animals. Orcas within a pod do not interbreed; mating occurs only between members of different pods.

Resident pods are generally larger than the transient and offshore pods, having up to 50 or more members. Several pods occasionally join to form what are referred to as superpods, sometimes numbering in excess of 150 animals.

The next level of grouping is the clan. A clan consists of those pods which have a similar dialect. Again the relationship between pods appears to be genealogical, consisting of fragments of families with a common heritage on the maternal side. Different clans can occupy the same geographical area; pods from different clans are often recorded traveling together. When resident pods come together to travel as a clan, they greet each other by forming two parallel lines akin to a face-off before mingling with each other.

The final layer of association, perhaps more arbitrary and devised by humans rather than the other very natural divisions, is called the community and is loosely defined as the set of clans that are regularly seen mixing with each other. Communities do not follow discernible familial or vocal patterns.

In the northeast Pacific, three communities of fish-eating orcas have been identified:

• The southern community (1 clan, 3 pods, 90 orcas as of 2006)
• The northern community (3 clans, 16 pods, 214 orcas as of 2000)
• The south Alaskan community (2 clans, 11 pods, 211 orcas as of 2000)

It should be emphasized that these hierarchies are valid for resident groups only. Transient groups are generally smaller because, although they too are based on matrilines, some male and female offspring eventually disperse from the maternal group. However, transient groups still have a loose connection defined by their dialect.

A summation of all these behavioral characteristics has been presented as an all-encompassing theory of cultural capabilities in the paper Culture in Whales and Dolphins (http://www.bbsonline.org/Preprints/Rendell/), which states: "The complex and stable vocal and behavioural cultures of sympatric groups of killer whales (Orcinus orca) appear to have no parallel outside humans and represent an independent evolution of cultural faculties."

As was alluded in the Diet secton above, orcas have highly adaptive and strategically successful hunting tactics. Furthermore, these tactics are learned behaviors rather than evolved characteristics. Orcas learn from one another readily, which supports the idea that orcas possess reasoning and problem solving abilities.

Vocal behavior

Orcas, like this one spotted near Alaska, commonly breach, often lifting their entire body out of the water.

See also: Whale song

As with other dolphins, orcas are very vocal animals. They produce a variety of clicks and whistles that are used for communication and echolocation. The vocalization types vary with activity. While resting they are much quieter, merely emitting an occasional call that is distinct from those heard when engaging in more active behaviour.

Fish-eating resident groups of orcas in the Northeast Pacific tend to be much more vocal than transient groups living in the same waters. Resident orcas feed on fish, particularly Pacific salmon, a prey with poor underwater hearing that cannot detect orca calls at any significant distance. Transient orcas on the other hand feed mainly on marine mammals and occasionally on seabirds. Because all marine mammals have excellent underwater hearing, transients probably remain silent for much of the time to avoid detection by their acoustically-sensitive prey. They sometimes use a single click (called a cryptic click) rather than the long train of clicks observed in other populations.

Resident pods have group-specific dialects. Each pod has its own vocal repertoire or set of particular stereotyped underwater calls (call types). Every member of the pod seems to know all the call types of the pod, so it is not possible to identify a single animal using voice alone. A particular call type might be used by only one group or shared among several.

The number of call types shared by two groups appears to be a function of their genealogical relatedness rather than their geographical distance. Two groups that share a common set of ancestors but have grown apart in distance are likely to have a similar set of call types, indicating that calls are a learned behaviour.

Furthermore, orca mothers have been observed training their young in the pod's dialect. The mother uses a simplified version of the pod's dialect when training a calf; a sort of baby-talk. This suggests that orca vocalization is about as instinctual as human linguistics.

Conservation

Environmental degradation, conflicts with fishing activities, and habitat degradation are currently the most significant threats to orcas worldwide.

Like other animals at the highest Trophic levels of the food chain, the orca is particularly susceptible to poisoning via accumulation of Polychlorinated biphenyls (PCBs) in the body. A survey of animals off the Washington coast found that PCB levels in orcas were higher than those in harbour seals in Europe that have been sickened by the chemical. Samples from the blubber of orcas in the Norwegian Arctic show higher levels of PCBs, pesticides and brominated flame-retardants than in Polar Bears. However, no direct evidence of sickness in orcas has been found. The most likely effect, if any, would be a reduced rate of reproduction or decreased ability to fight off disease (immunodepression).

Noise from shipping, drilling, and other human activities can interfere with the acoustic communication and echolocation of orcas. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Orcas subsequently avoided the surrounding waters. Orcas are popular with whale watchers, which may change orca behavior and stress orcas, particularly if boats approach orcas too closely or block their line of travel.

In 2005, the United States government listed the Southern Resident community of orcas as an endangered population under the Endangered Species Act. The Southern Resident community comprises three pods which spend most of the year in the Georgia and Haro Straits and Puget Sound in British Columbia and Washington state. These orcas do not breed outside of their community, which was previously estimated at around 200 animals and had shrunk to around 90.

The Exxon Valdez oil spill had an adverse effect on orcas in Prince William Sound and the Kenai Fjords region of Alaska. One resident pod was caught in the spill; though the pod successfully swam to clear water, eleven members of the pod (about half) disappeared in the following year. The spill had a long-term effect in reducing the amount of available prey, such as salmon, and has thus been responsible for a local population decline. In December 2004, scientists at the North Gulf Oceanic Society said that the AT1 transient population of orcas, now only numbering 7 individuals, has failed to reproduce at all since the spill. This population is expected to become extinct.

Orcas and humans

Although only scientifically identified as a species in 1758, the orca has been known to humans since prehistoric times.

The first written description of an orca is given in Pliny the Elder's Natural History (written circa 70 AD). The aura of invincibility around the all-consuming orca was well-established by this time. Having observed the public slaughter of a whale stranded at a harbor near Rome, Pliny writes, "Orcas, (the appearance of which no image can express, other than an enormous mass of savage flesh with teeth), are the enemy of [other whales]... they charge and pierce them like warships ramming."

Whaling

A male orca with its characteristic tall dorsal fin swims in the waters near Tysfjord, Norway

Orcas were targeted in commercial whaling for the middle part of the twentieth century once stocks of larger species had been depleted. Commercial hunting of orcas came to an abrupt halt in 1981 with the introduction of a moratorium on all whaling. (Although from a taxonomic point of view an orca is a dolphin rather than a whale, it is sufficiently large to come under the purview of the International Whaling Commission.)

The greatest hunter of orcas was Norway, which took an average of 56 animals per year from 1938 to 1981. Japan took an average of 43 animals from 1946 to 1981. (War year figures are not available but are likely to be fewer). The Soviet Union took a few animals each year in the Antarctic, with the extraordinary exception of the 1980 season when it took 916.

Today, no country carries out a substantial hunt. Japan usually takes a few individuals each year as part of its controversial program of scientific research as specified in IWC constitution. A similarly small level of subsistence whaling is carried out by Indonesia and Greenland. As well as being hunted for their meat, orcas have also been killed because of competition with fishermen. In the 1950s the United States Air Force, at the request of the Government of Iceland, used bombers and riflemen to slaughter orcas in Icelandic waters because they competed with humans for fish. The operation was considered a great success at the time by fishermen and the Icelandic government. However, many were unconvinced that orcas were responsible for the drop in fish stocks, blaming overfishing by humans instead. This debate has led to repeated studies of North Atlantic fish stocks, with neither side in the whaling debate giving ground since that time.

Orcas have been known to co-operate with humans in the hunting of other whales. One well-known example occurred near the port of Eden in South-Eastern Australia in the 1920s. A pod of orcas, led by a dominant male called Old Tom, would assist whalers in hunting baleen whales. The orcas would find the target whales, shepherd them into Twofold Bay and then alert the whalers to their presence and often help to kill the whales. After being speared, some of the whales would even grab the ropes in their teeth and haul the whales in along with the human. The skeleton of Old Tom is on display at the Eden Killer Whale Museum, and significant wear marks still exist on his teeth from repeatedly grabbing fast moving ropes. In return for their help, the whalers allowed the orcas to eat the tongue and lips of the whale before hauling it ashore. The orcas would then also feed on the many fish and birds that would show up to pick at the smaller scraps and runoff from the fishing. Fear of orcas has dissipated in recent years due to better education about the species, including the appearance of orcas in aquariums.

Captivity

See also: List of marine parks with Orcas

The orca's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquariums and aquatic theme parks. The first orca capture and display occurred in Vancouver in 1964. Over the next 15 years around 60 or 70 orcas were taken from Pacific waters for this purpose. In the late 1970s and the first half of the 1980s, orcas were generally taken from Icelandic waters (50 in the five years to 1985). Since that time, orcas have been successfully bred in captivity and wild specimens are considerably rarer.

The practice of keeping orcas in captivity is controversial, and organisations such as the World Society for the Protection of Animals and the Whale and Dolphin Conservation Society campaign against the captivity of orcas.

Shamu (played by Orkid) posing at Seaworld, San Diego

Orcas in captivity may develop physical pathologies such as dorsal fin collapse, seen in 60-90% of captive males. Captive orcas have vastly reduced life expectancies, on average only living into their 20s. In the wild, females may live into their 90s. The captive environment usually bears little resemblance to their wild habitat, and the social groups that the orcas are put into are completely foreign to those found in the wild [1]. Critics claim that captive life is stressful due to small tanks, false social groupings and chemically-altered water. Captive orcas have occasionally acted aggressively towards themselves, other orcas, or humans, which critics say is a result of stress.

Dorsal fin collapse

Several theories exists as to why the dorsal fin of male orcas collapses. One theory is that the collagen, or compressed lipid cells, which holds the tall dorsal fin erect is not strong enough when the orca is placed in captivity. The collagen normally hardens in late adolescence, in which the orca spends much time in deep ocean waters, and it is theorized that the pressure the water exerts on the fin allows it to remain supported while the collagen hardens. In captivity, however, shallow tanks lack sufficient water pressure to produce this effect, and the fin collapses before the collagen solidifies . Another theory states that the whale is almost always in a state of turning in a tank, since it is not large enough to allow swimming in one direction for any normal duration. The constant turning exerts pressure on the dorsal fin, which in turn causes it to collapse .

Attacks on humans

Aside from a boy who was charged (but not grabbed) while swimming in a bay in Alaska, there have been no confirmed attacks on humans in the wild. However, there have been several instances of captive orcas attacking their trainers or intruders. ABC News has reported that orcas have attacked nearly two dozen people since the 1970s.

• On April 20, 1971; SeaWorld secretary Annette Eckis was riding on Shamu at the park in San Diego, California. Ms. Eckis slid off and Shamu grabbed her leg in its mouth. After a few minutes, Shamu was coaxed into letting Ms. Eckis let go, and she was taken away from the tank on a stretcher, and required 100 stitches on her leg. Ms. Eckis was wearing a bikini and this could have made Shamu curious as other orca trainers usually wear wet suits. [2]

• On February 20, 1991, a group of 3 orcas (Haida, Nootka, and Tillikum) killed a trainer named Keltie Byrne at Sealand in Victoria, British Columbia (where employees were not allowed in the water with orcas). After this, and due to Tilikum being bullied by the two females in the tank, Tilly (as he is nicknamed) was relocated to SeaWorld of Orlando, Florida, where he remains. He is currently the largest orca in captivity.

• On July 26, 1999, at the SeaWorld park in Orlando, Florida, a man with a history of mental illness hid at Sea World after hours and climbed into the orca tank with Tilikum, the park's huge bull. The next morning, the nude man was found dead, draped across Tilikum's back. Although some claimed that Tilikum killed the man, an autopsy revealed that the cause of death was hypothermia.

• In late July 2004, during a show at the SeaWorld park in San Antonio, Texas, an orca pushed its trainer of ten years underwater and barred the way to the rim of the pool; the trainer could only be rescued from the animal after several minutes.

• On November 29, 2006, Kasatka at SeaWorld twice grabbed its trainer by the foot (breaking it in the process) and pulled him underwater. Trainers from the SeaWorld parks met to try and figure out why that happened.[3]

Other incidents

One of the more infamous incidents involving orca aggression took place in August 1989, when a dominant female orca, Kandu V, struck a newcomer orca, Corky II, with her mouth during a live show. Corky II had been imported from Marineland California just months prior to the incident. According to reports, a loud smack was heard across the stadium. Although trainers tried to keep the show rolling, the blow severed an artery near Kandu V's jaw, and she began spouting blood. The crowd was quickly ushered out, and after a 45-minute hemorrhage, Kandu V died. A photograph of Kandu V bleeding to death does exist, see external links section of this document. Opponents of these shows, such as PETA, see these incidents as supporting their criticism.

SeaWorld continued to be under criticism from the Born Free Foundation over its continued captivity of the orca Corky II, who they want returned to her family, the A5 Pod, a large pod of orcas in British Columbia, Canada [4].

The captive orca Namu developed a bacterial infection which damaged his nervous system, causing him to become non-responsive to people. During his illness he charged full speed into the wire mesh of his pen, thrashed violently for a few minutes and then died.[5] A semi-documentary was named after him.[6]

Cultural references

Mythologized orca and whales surround Thule on the Carta marina.

Indigenous peoples in the Pacific Northwest of North America such as the Kwakwaka'wakw, Coast Salish, Nuu-chah-nulth, Tlingit, Haida, and Tsimshian have featured the orca prominently in their culture through history, art, spirituality and religion.

Creatures by the name of orca or "orc" have appeared throughout the history of Western literature. In Ludovico Ariosto's epic poem Orlando Furioso, the orca (sometimes translated "orc") was a sea-monster from whom the damsel Angelica was rescued by Orlando. This Orca-like sea monster first appears in English in Michael Drayton's Polyolbion, an epic poem about Brutus the Trojan, the mythical founder of Great Britain]. It later appears in John Milton's epic poem Paradise Lost.

As late as the 1970s, orca were depicted negatively in fiction as ravenous predators whose behavior caused heroes to interfere to help a prey animal escape. The poorly-received film Orca features the story of a male orca going on a vengeful rampage after his pregnant mate is killed by humans. In Jaws (1975), the name of the boat used to hunt the shark is called the Orca, given the orca's status as a known enemy of the shark.

In recent years, increased research and the animal's popularity in public venues has brought about a dramatic rehabilitation of the orca's image, much as the North American Wolf's image has been changed.It is now widely seen as a respected predator that poses little actual threat to humans.

The film Free Willy (1993) focused on the quest for freedom for a captive orca. The orca starring in the movie, Keiko, was originally captured in Icelandic waters. After rehabilitation at the Oregon Coast Aquarium in Newport, Oregon, he was later returned to the waters of the Nordic countries, his native habitat, but continued to be dependent on humans until he died of pneumonia in December 2003. The film Happy Feet featured an attack on penguins, in which they demonstrated various documented behaviours, such as spyhopping, flinging their prey into the air (inspired by the images in the nature documentary The Blue Planet) and beaching themselves to attack.

Nomenclature

The name "orca" (plural "orcas") was originally given to these animals by the ancient Romans, possibly borrowed from the Greek word ὄρυξ which (among other things) referred to a species of whale. The term "orc" (or its variant "ork") has been used to describe a large fish, whale or sea-monster. It is now considered an obsolete equivalent for "orca."

The name "killer whale" is widely used in common English. However, since the 1960s, "orca" has steadily grown in popularity as the common name to identify the species, and both names are now used. The species is called orca in most other European languages, and, as there has been a steady increase in the amount of international research on the species, there has been a convergence in naming.

It is commonly thought that 18th-century Spanish sailors dubbed these creatures asesina-ballenas, or "whale killer" as orcas do attack large whales. However, this title was improperly translated into English as "killer whale". The term became so prevalent that Spanish speakers commonly used its retranslation of ballena asesina.

Supporters of the original name point out that the naming heritage is not limited to Spanish sailors. Indeed the genus name "Orcinus" means "from Hell" (see Orcus), and although the name "orca" (in use since antiquity) is probably not etymologically related, the assonance might have given some people the idea that it means "whale that brings death," or "demon from hell."

The name of this species is similarly intimidating in many other languages. In Finnish and in Dutch it is called miekkavalas and zwaardwalvis respectively, which means "sword whale". To the Haida people native to the islands of Haida Gwaii off the coast of British Columbia, the animal was known as skana or "killing demon". The Japanese call them shachi (鯱), whose kanji character combines the radicals for fish (魚) and tiger (虎). In Chinese it's called "虎鲸" (tiger whale) or "逆戟鲸" (reversed halbert whale).

They are sometimes referred to as blackfish, a group including pilot whales, pygmy and false killer whales, and melon-headed whales.

A former name for the species is grampus. This is now seldom used and should not be confused with the Grampus genus (containing Risso's Dolphin).

See also

• Famous orcas
• Cetacean intelligence

Notes and references

General references

• "Orcinus orca". Integrated Taxonomic Information System. 18 March. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• Orca: The Whale Called Killer, Erich Hoyt, Camden House Publishing, ISBN 0-920656-25-0
• Killer Whale, John K.B. Ford, pp669-675 in the Encyclopedia of Marine Mammals, Academic Press, ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell. Alfred A. Knopf. ISBN 0-375-41141-0
• Kharakter vzaimootnoshenii kasatok i drugikh kitoobraznykh in Morskie mlekopitayushchie (in Russian, transliterations vary). "The nature of interrelationships between Killer Whales and Other Cetaceans" I.V.Shevchenko, 1975 pp173-175. (The author describes his discovery of Orca cannibalism).
• Ellis, Graeme. Guardians of the Whales. Whitecap Books. ISBN 1-55110-034-7. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Ford, John K.B. Killer Whales. UBC Press. ISBN 0-7748-0469-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

• Orca-Live
• A captive orca photo database
• A database of wild orcas
• Killer whale images, Tysfjord, Norway
• Monterey Bay Whale Watch Photos: Killer Whales Attacking Gray Whales
• Predation Behavior of Transient Killer Whales in Monterey Bay, California
• Research project studying Killer whales in the Norwegian Arctic
• New Zealand, Papua New Guinea and Antarctic orca research
• Photograph of Kandu V bleeding to death at Sea World - WARNING: Disturbing Content