Orca
Encyclopedia
The killer whale commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale
belonging to the oceanic dolphin
family. Killer whales are found in all oceans, from the frigid Arctic
and Antarctic regions to tropical seas. Killer whales as a species have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammal
s such as sea lion
s, seals
, walrus
es and even large whale
s. Killer whales are regarded as apex predator
s, lacking natural predators and preying on even large sharks.
Killer whales are highly social
; some populations are composed of matrilineal family groups which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been described as manifestations of culture
.
The IUCN currently assesses the orca's conservation status
as data deficient
because of the likelihood that one 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 fisheries
. In late 2005, the killer whales known as the "southern resident killer whales
" were placed on the U.S. Endangered Species list.
Wild killer whales are not considered a threat to humans, although there have been cases of captives 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.
in 1758 in Systema Naturae
. Konrad Gessner wrote the first scientific description of a killer whale in his "Fish book" of 1558, based on examination of a dead stranded
animal in the Bay of Greifswald
that had attracted a great deal of local interest.
The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The killer whale lineage probably branched off shortly thereafter. Although it has morphological
similarities with the pygmy killer whale
, the false killer whale
and the pilot whale
s, a study of cytochrome b
gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins
of the genus Orcaella.
."
Ancient Romans
originally applied orca (plural orcae) to these animals, possibly borrowing it from the Greek , which referred (among other things) to a whale species. Since the 1960s, orca has steadily grown in popularity; both names are now used. The term orca is preferred by some to avoid the negative connotations of "killer", and because, being part of the family Delphinidae, the species is more closely related to other dolphins than to whales.
They are sometimes referred to as blackfish, a name used for some whale species as well. Grampus is a former name for the species, but is now seldom used. This meaning of grampus should not be confused with the Grampus genus, whose only member is Risso's Dolphin
.
, subspecies
, or possibly even species
. The IUCN reported in 2008, "The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years." In the 1970s and 1980s, research off the west coast of Canada and the United States identified the following three types:
Transients and residents live in the same areas, but avoid each other. The name "transient" originated from the belief that these killer whales were outcasts from larger resident pods. Researchers later discovered transients are not born into resident pods or vice-versa. The evolutionary split between the two groups is believed to have begun two million years ago. Genetic data indicates that the types have not interbred for up to 10,000 years.
Other populations have not been as well studied, although specialized fish-eating and mammal-eating killer whales have been distinguished elsewhere. Separate populations of fish-eating and mammal-eating killer whales have been identified around the United Kingdom. Fish-eating killer whales in Alaska
and Norway
have resident-like social structures, while mammal-eating killer whales in Argentina
and the Crozet Islands
behave more like transients.
Three types have been documented in the Antarctic
. Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers are skeptical about their status, and it is difficult to link these directly to the types described below.
Types B and C live close to the ice pack, and diatoms in these waters may be responsible for the yellowish coloring of both types. Mitochondrial DNA
sequences support the theory that these are separate species that have recently diverged. More recently, complete mitochondrial sequencing indicates that the two Antarctic groups that eat seals and fish should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.
Research is ongoing into the genetic relationships among killer whale types, and whether the types that have been identified represent deep evolutionary trends. For example, it was long thought that mammal-eating killer whales were likely to be closely related to other mammal-eating killer whales from different regions, but genetic testing refuted this hypothesis.
Killer whales distinctively bear a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. Killer whales have a heavy and robust body with a large dorsal fin up to 2 metres (6.6 ft) tall. Behind the fin, they have a dark grey "saddle patch" across the back. Antarctic killer whales may have pale grey to nearly white backs. Adult killer whales are very distinctive and are not usually confused with any other sea creature. When seen from a distance, juveniles can be confused with other cetacean species such as the false killer whale
or Risso's dolphin
. The killer whale's teeth are very strong and covered in enamel
. Its jaws are a powerful gripping apparatus, as the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The front teeth are inclined slightly forward and outward, thus allowing the killer whale to withstand powerful jerking movements from its prey while the middle and back teeth hold it firmly in place.
Killer whales are the largest extant members of the dolphin family. Males typically range from 6 to 8 m (19.7 to 26.2 ) long and weigh in excess of 6 tonnes (5.9 LT). Females are smaller, generally ranging from 5 to 7 m (16.4 to 23 ) and weighing about 3 to 4 t (3 to 3.9 ). The largest male killer whale on record was 9.8 metres (32.2 ft), weighing over 10 tonnes (9.8 LT), while the largest female was 8.5 metres (27.9 ft), weighing 7.5 tonnes (7.4 LT). Calves at birth weigh about 180 kilograms (396.8 lb) and are about 2.4 metres (7.9 ft) long. The killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (58.8 km/h). The skeleton of the killer whale is of the typical delphinid structure but is more robust in all respects. The killer whale's integument, unlike that of most other dolphin species, is characterised by a well-developed dermal layer with a dense network of fascicle
s of collagen
fibers.
Killer whale pectoral fins are large and rounded, resembling paddles. Males have significantly larger pectoral fins than females. At about 1.8 metres (5.9 ft) the male's dorsal fin is more than twice the size of the female's and is more of a triangular shape—a tall, elongated isosceles triangle—whereas hers is shorter and more curved. Males and females also have different patterns of black and white skin in the genital area. Sexual dimorphism
is also apparent in the skull; adult males have a longer lower jaw than females, and have a larger occipital crest.
Individual killer whales can often be identified from the dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals. Photo identification has enabled the local population of killer whales to be counted each year rather than estimated and has enabled great insight into lifecycles and social structures.
White killer whales occur sporadically among normal killer whales, but are rare. They have been spotted in the northern Bering Sea
and around St. Lawrence Island
, and near the Russia
n coast. In February 2008, a white killer whale was photographed 2 miles (3.2 km) off Kanaga
Volcano.
Killer whales have good eyesight above and below the water, excellent hearing, and a good sense of touch. They have exceptionally sophisticated echolocation
abilities, detecting the location and characteristics of prey and other objects in their environment by emitting clicks and listening for echoes.
Female killer whales mature at around age 15. They then have periods of polyestrous cycling with non-cycling periods of between 3 and 16 months. Gestation
varies from 15 to 18 months. Mothers calve, with usually a single offspring, about once every 5 years. In resident pods, birth occurs at any time of year, although winter is the most popular. Mortality is extremely high during the first six to seven months of life, when 37–50% of all calves die. Weaning
begins at about 12 months and completes by the age of two. According to observations in several regions, all male and female killer whale pod members participate in the care of the young. Killer Whales and Pilot whales are the only species in which the females go through menopause and live for decades after they have finished breeding. Killer whales are unique among cetaceans, as their heads become shorter as they age.
Females breed until age 40, meaning that on average they raise five offspring. The lifespan of wild females averages 50 years, with a maximum of 80–90 years. Males sexually mature at the age of 15 but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of 50–60 years. One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales
, Australia. This would have made him up to 90 years old. Examination of his teeth indicated he died around age 35, but this method of age determination is now believed to be inaccurate for older animals. One male well known to researchers in the Pacific Northwest
called Ruffles (J1) was estimated to have been born in 1951, making him 59 years old when he died in 2010. Captive killer whale lifespans are typically significantly shorter, usually less than 25 years; however, numerous individuals are alive in their thirties, and a few have reached their 40s. In many instances, the lifespans of killer whales depend on the will of the animal.
Killer whales are found in all oceans and most seas. Due to their enormous range, numbers and density, distributional estimates are difficult to compare, but they clearly prefer higher latitudes and coastal areas over pelagic
environments.
Systematic surveys indicate the highest densities of killer whales (>0.40 individuals per 100 km²) in the northeast Atlantic around the Norwegian
coast, in the north Pacific along the Aleutian Islands, the Gulf of Alaska
and in the Southern Ocean
off much of the coast of Antarctica. They are considered "common" (0.20–0.40 individuals per 100 km²) in the eastern Pacific along the coasts of British Columbia
, Washington and Oregon
, in the North Atlantic Ocean around Iceland
and the Faroe Islands
. High densities have also been reported but not quantified in the western North Pacific around the Sea of Japan
, Sea of Okhotsk
, Kuril Islands
, Kamchatka and the Commander Islands and in the southern hemisphere off the coasts of South Australia
, Patagonia
, off the coast of southern Brazil
and the tip of southern Africa
. They are reported as seasonally common in the Canadian Arctic, including Baffin Bay
between Greenland
and Nunavut
, and around Tasmania
and Macquarie Island
. Information for offshore regions and tropical waters is more scarce, but widespread, if not frequent, sightings indicate that the killer whale can survive in most water temperatures. There have been sightings, for example, in the Mediterranean
, the Arabian
Sea, the Gulf of Mexico
and the Indian Ocean
around the Seychelles
.
Probably the largest population lives in Antarctic waters, where they range up to the edge of the pack ice and are believed to venture into the denser pack ice, finding open leads
much like beluga whales in the Arctic. In contrast, killer whales are seasonal summer visitors to Arctic waters, where they do not approach the ice pack. With the rapid Arctic sea ice decline in the Hudson Strait
, their range now extends deep into the northwest Atlantic.
Migration patterns are poorly understood. Each summer, the same individuals appear off the coasts of British Columbia and Washington State. Despite decades of research, where these animals go for the rest of the year remains unknown. Transient pods have been sighted from southern Alaska to central California. Resident killer whales sometimes travel as much as 160 kilometres (99.4 mi) in a day, but may be seen in a general area for a month or more. Resident killer whale pod ranges vary from 320 to 1300 km (198.8 to 807.8 ).
Occasionally, killer whales swim into freshwater rivers. They have been documented 100 miles (160.9 km) up the Columbia River
in the United States. They have also been found in the Fraser River
in Canada and the Horikawa River
in Japan.
Killer whales hunt varied prey; however, different populations/species tend to specialize and some can have a dramatic impact on certain preyed species. For example, some populations in the Norwegian
and Greenland
sea specialize in herring
and follow that fish's autumnal migration to the Norwegian coast. Other populations prey on seals. Salmon
account for 96% of northeast Pacific residents' diet. 65% of them are large, fatty Chinook
. Chum salmon are also eaten, but smaller sockeye and pink salmon are not a significant food item. Depletion of specific prey species in an area is therefore cause for concern for local populations, despite the high diversity of prey. On average, a killer whale eats 227 kilograms (500.4 lb) each day.
Because some killer whales prey on large whales and shark
s, they are considered to be apex predator
s. They are sometimes called the wolves of the sea, because they hunt in groups like wolf packs.
. In New Zealand
, rays
are killer whales' most frequent prey, and they have also been observed hunting shark
s (particularly makos, threshers
and smooth hammerhead
s). Squid and sea turtles are also taken.
While salmon are usually hunted by an individual or a small group of individuals, herring are often caught using carousel feeding
: the killer whales force the herring into a tight ball by releasing bursts of bubbles or flashing their white undersides. They then slap the ball with their tail flukes, either stunning or killing up to 10–15 at a time. The herring are then eaten one at a time. Carousel feeding has only been documented in the Norwegian killer whale population and with some oceanic dolphin species.
Killer whales can induce tonic immobility
in sharks and rays by holding them upside down, rendering them helpless and incapable of injuring the whale. Some sharks suffocate within about 15 minutes while the whale holds them still, because these sharks need to move to breathe. In one incident filmed near the Farallon Islands
, a female killed a 3 – long great white shark
, apparently after swimming with it upside-down in her mouth and inducing tonic immobility in it. She and another pod member ate the shark's liver and allowed the rest of the carcass to sink.
In July 1992, two killer whales attacked, killed and fed on an 8 metres (26.2 ft) long whale shark
, Rhincodon typus, in the waters off Bahia de los Angeles in Baja California
.
Killer whales are very sophisticated and effective predators. Twenty-two cetacean species have been recorded as killer whale prey, from examining either stomach
contents, scar
ring on the prey's body, or feeding activity. Groups even attack larger cetaceans such as minke whale
s, gray whale
s, and rarely sperm whale
s or blue whale
s.
Hunting large whales usually takes several hours. Killer whales generally choose to attack young or weak animals instead. However, a group of five or more may attack a healthy adult. When hunting a young whale, a group chases it and its mother until they wear out. Eventually they separate the pair and surround the calf, preventing it from surfacing to breathe, drowning it. Pods of female sperm whales sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using them to repel the attackers. Rarely, large killer whale pods can overwhelm even adult female sperm whales. Adult bull sperm whales, which are large, powerful and aggressive when threatened, and fully-grown adult blue whales, who are possibly too large to overwhelm, are not believed to be predated by killer whales.
Other marine mammal prey species include most species of seal
, sea lion
and fur seal
. Walrus
es and sea otter
s are less frequently taken. Often, to avoid injury, killer whales 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. Sea lions are killed by head-butting or after a stunning blow from a tail fluke. In the Aleutian Islands, a decline in sea otter
populations in the 1990s was controversially attributed by some scientists to killer whale predation, although there is no direct evidence of this. The decline of sea otters followed a decline in harbour seal and Steller sea lion populations, the killer whale's preferred prey, which in turn may be substitutes for their original prey, now decimated by industrial whaling.
In steeply banked beaches off Península Valdés, Argentina, and the Crozet Islands
, killer whales feed on South American sea lion
s and southern elephant seal
s in shallow water, even beaching
temporarily to grab prey before wriggling back to the sea. Beaching, usually fatal to cetaceans, is not an instinctive behavior, and can require years of practice for the young.
"Wave-hunting" killer whales spy-hop to locate Weddell seal
s, Ross seals
, crabeater seal
s and leopard seal
s resting on ice floes and then swim in groups to create waves that wash over the floe. This washes the seal into the water where other killer whales lie in wait.
Killer whales have also been observed preying on terrestrial
mammals, such as deer
and moose
swimming between islands off the northwest coast of North America. Killer whale cannibalism
has also been reported based on analysis of stomach contents, but this is likely to be the result of scavenging remains dumped by whalers. One killer whale was also attacked by its companions after being shot. Although resident killer whales have never been observed to eat other marine mammals, they occasionally harass and kill porpoise
s and seals
for no apparent reason.
s, cormorant
s and gull
s. A captive killer whale at MarineLand
discovered that it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Four other killer whales then learned to copy the behavior.
Day-to-day killer whale behavior generally consists of foraging, travelling, resting and socializing. Killer whales are frequently active at the surface, engaging in acrobatic behaviors such as breaching, spyhopping, and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging parasites, or play. Spyhopping, a behaviour in which a whale holds its head above water, helps the animal view its surroundings.
Resident killer whales swim with porpoise
s, other dolphin
s, seals
, and sea lion
s, which are common prey for transient killer whales.
s and higher primate
s, such as humans, live in comparably complex social structures. Due to orcas' complex social bonds and society, many marine experts have concerns about how humane it is to keep these animals in captive situations. Resident killer whales in the eastern North Pacific have a particularly complex and stable social grouping system. Unlike any other mammal species whose social structure is known, residents live with their mothers for their entire lives. These societies are based on matrilines consisting of the matriarch and her descendants who form part of the line, as do their descendants. The average size of a matriline is 5.5 animals.
Because females can reach age 90, as many as four generations travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. With one exception, the killer whale named Luna
, no permanent separation of an individual from a resident matriline has been recorded.
Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may separate for weeks or months at a time. DNA
testing indicates that resident males nearly always mate with females from other pods.
Clans are the next level of resident social structure, and are composed of pods with similar dialects and common but older maternal heritage. Clan ranges overlap, mingling pods from different clans.
The final association layer, perhaps more arbitrarily defined than the familial groupings, is called the community and is defined as a set of clans that regularly commingle. Clans within a community do not share vocal patterns.
Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mothers than females. These bonds can extend well into adulthood. Unlike residents, extended or permanent separation of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become “rovers” and do not form long-term associations, occasionally joining groups that contain reproductive females. As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted.
Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters. Residents feed primarily on salmon
, whose hearing is too poor to detect killer whale calls at any relevant distance. Residents make sounds to identify themselves when they approach another marine mammal
.
Transient are typically silent probably to avoid alerting their mammalian prey, all of whom have excellent underwater hearing. They sometimes use a single click (called a cryptic click) rather than the long train of clicks observed in other populations.
All members of a resident pod use similar calls, known collectively as a dialect. Dialects are composed of specific numbers and types of discrete, repetitive calls. They are complex and stable over time. Call patterns and structure are distinctive within matrilines. Newborns produce calls similar to their mothers, but have a more limited repertoire. Individuals likely learn their dialect through contact with their mother and other pod members. For instance, family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them. Dialects are probably an important means of maintaining group identity and cohesiveness. Similarity in dialects likely reflects the degree of relatedness between pods, with variation building over time.
Researchers have not determined whether calls have particular meanings or are associated with specific types of activity. Resident dialects contain 7–17 (mean = 11) distinctive call types. Transient dialects are much different, having only 4–6 discrete calls, none of which they share with residents. All members of the North American west coast transient community express the same basic dialect, although minor regional variation in call types is evident. Preliminary research indicates that offshore killer whales have group-specific dialects that are unlike those of residents and transients.
in captivity and are often described as intelligent, although defining and measuring "intelligence" is difficult in a species whose environment and behavioral strategies are very different from those of humans.
Killer whales imitate others, and seem to deliberately teach skills to their kin. This is most strikingly seen when killer whales deliberately beach
themselves to catch seals. Off Península Valdés, adults sometimes pull seals off the shoreline and then release them again near juvenile whales, allowing the younger whales to practice the difficult capture technique on the now-weakened prey. Off the Crozet Islands
, mothers push their calves onto the beach, waiting to pull the youngster back if needed.
People who have interacted closely with killer whales offer numerous anecdotes
demonstrating the whales' curiosity, playfulness, and ability to solve problems. For example, Alaskan killer whales have not only learned how to steal fish from longlines, but have overcome a variety of techniques designed to stop them, such as the use of unbaited lines as decoys. Once, fishermen placed their boats several miles apart, taking turns retrieving small amounts of their catch, in the hope that the whales would not have enough time to move between boats to steal fish as it was being retrieved. A researcher described what happened next:
In other anecdotes, researchers describe incidents in which wild killer whales playfully tease humans by repeatedly moving objects that the humans are trying to reach, or suddenly start to toss around a chunk of ice after a human throws a snowball.
The killer whale's use of dialects and the passing of other learned behaviours from generation to generation have been described as a form of culture
.
from conservation dependent
to data deficient
, recognizing that one or more killer whale types may actually be separate, endangered species
. Depletion of prey species, pollution, large-scale oil spill
s, and habitat disturbance caused by noise and conflicts with boats are currently the most significant worldwide threats.
Like other animals at the highest trophic level
s, the killer whale is particularly at risk of poisoning from accumulation of toxins, including polychlorinated biphenyl
s (PCBs). European Harbour seals have problems in reproductive and immune functions associated with high levels of PCBs and related contaminants, and a survey off the Washington coast found that PCB levels in killer whales were higher than levels that had caused health problems in harbour seals. Blubber samples in the Norwegian
Arctic
show higher levels of PCBs, pesticides and brominated flame-retardant
s than in polar bear
s. When food is scarce, killer whales metabolize blubber
for energy, which increases pollutant concentrations.
In the Pacific Northwest, wild salmon stocks, a main resident food source, have declined dramatically in recent years. On the west coast of Alaska and the Aleutian Islands, seal and sea lion populations have also substantially declined.
In 2005, the United States government listed the southern resident
community as an endangered population under the Endangered Species Act
. The southern resident community comprises three pods which live mostly in the Georgia
and Haro Straits and Puget Sound
in British Columbia
and Washington. They do not breed outside of their community, which was once estimated at around 200 animals and later shrank to around 90. In October 2008, the annual survey revealed that seven were missing and presumed dead, reducing the count to 83. This is potentially the largest decline in the population in the past ten years. These deaths can be attributed to declines in chinook salmon
.
Noise from shipping, drilling, and other human activities is a significant concern in some key killer whale habitats, including Johnstone Strait
and Haro Strait
. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Killer whales also avoided the surrounding waters. High-intensity sonar used by the Navy
disturbs killer whales along with other marine mammals. Killer whales are popular with whale watchers
, which may stress the whales and alter their behavior, particularly if boats approach too closely or block their line of travel.
The Exxon Valdez oil spill
adversely affected killer whales in Prince William Sound
and Alaska's Kenai Fjords region. Eleven members (about half) of one resident pod disappeared in the following year. The spill damaged salmon and other prey populations, which in turn damaged local killer whales. By 2009, scientists estimated the AT1 transient population (considered part of a larger population of 346 transients), numbered only 7 individuals and had not reproduced since the spill. This population is expected to die out.
The indigenous peoples of the Pacific Northwest Coast
feature killer whales throughout their history, art, spirituality and religion. The Haida regarded killer whales as the most powerful animals in the ocean, and their mythology tells of killer whales living in houses and towns under the sea. According to these myths, killer whales took on human form when submerged, and humans who drowned went to live with them. For the Kwakwaka'wakw
, the killer whale was regarded as the ruler of the undersea world, with sea lion
s for slaves and dolphins for warriors. In Kwakwaka'wakw and Nuu-chah-nulth mythology, killer whales may embody the souls of deceased chiefs. The Tlingit of southeastern Alaska regarded the killer whale as custodian of the sea and a benefactor of humans.
The Maritime Archaic
people of Newfoundland also had great respect for killer whales, as evidenced by stone carvings found in a 4,000-year-old burial site at the Port au Choix
National Historic Site.
In the tales and beliefs of the Siberian Yupik
people, killer whales are said to appear as wolves in winter, and wolves as killer whales in summer. Killer whales are believed to assist their hunters in driving walrus. Reverence is expressed in several forms: the boat represents the animal, and a wooden carving hung from the hunter's belt. Small sacrifice
s such as tobacco are strewn into the sea for them. Killer whales were believed to have helped the hunters even when in wolf guise, by forcing reindeer to allow themselves to be killed.
s, killer whales were historically feared as dangerous, savage predators. The first written description of a killer whale was given by Pliny the Elder
in circa AD 70, who wrote, "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."
There have been very few confirmed attacks on humans by wild killer whales, none of which has been fatal. In one instance, killer whales tried to tip ice floes on which a dog team and photographer of the Terra Nova Expedition
was standing. There is speculation that the sled dogs' barking may have sounded enough like seal calls to trigger the killer whale's hunting curiosity. In the 1970s, a surfer in California was bitten, and in 2005 a boy in Alaska who was splashing in a region frequented by harbor seals was bumped by a killer whale that apparently misidentified him as prey. Unlike wild killer whales, captive killer whales are reported to have made nearly two dozen attacks on humans
since the 1970s, some of which have been fatal.
Competition with fishermen also led to killer whales being regarded as pests. In the waters of the Pacific Northwest
and Iceland
, the shooting of killer whales was accepted and even encouraged by governments. As an indication of the intensity of shooting that occurred until fairly recently, about 25% of the killer whales captured in Puget Sound
for aquaria through 1970 bore bullet scars. The U.S. Navy claimed to have deliberately killed hundreds of killer whales in Icelandic waters in 1956.
, a resident that had been harpooned off Saturna Island
in 1964. So little was known at the time that it was nearly two months before the whale's keepers discovered what food (fish) it was willing to eat. To the surprise of those who saw him, Moby Doll was a docile, non-aggressive whale that made no attempts to attack humans.
Between 1964 and 1976, 50 killer whales from the Pacific Northwest were captured for display in aquaria
, and public interest in the animals grew. Millions of people became interested in killer whales after viewing them in captivity. In the 1970s, research pioneered by Michael Bigg
led to the discovery of the species' complex social structure, its use of vocal communication, and its extraordinarily stable mother-offspring bonds. Through photo-identification
techniques, individuals were named and tracked over decades.
Bigg's techniques also revealed that the Pacific Northwest population was small—in the low hundreds rather than the thousands that had been previously assumed. The Southern Resident community alone had lost 48 of its members to captivity; by 1976, only 80 remained. In the Pacific Northwest, the species that had unthinkingly been targeted became a cultural icon within a few decades.
The public's growing appreciation also led to growing opposition to whale–keeping in aquaria. Only one whale has been taken in North American waters since 1976. In recent years, the extent of the public's interest in killer whales has manifested itself in several high-profile efforts surrounding individuals. Following the success of the 1993 film Free Willy
, the movie's captive star Keiko was returned to the coast of his native Iceland
. In 2002, the orphan Springer
was discovered in Puget Sound
, Washington. She became the first whale to be successfully reintegrated into a wild pod after human intervention, crystallizing decades of research into the vocal behavior and social structure of the region's killer whales. The saving of Springer raised hopes that another young killer whale named Luna
who had become separated from his pod could be returned to it. However, his case was marked by controversy about whether and how to intervene, and in 2006 Luna was killed by a boat propeller.
industry caught immense numbers of baleen
and sperm whales, but largely ignored killer whales because of their limited amounts of recoverable oil, their smaller populations, and the difficulty of taking them. Once the stocks of larger species were depleted, killer whales were targeted by commercial whalers in the mid-20th century. Between 1954 and 1997, Japan
took 1,178 killer whales and Norway
took 987. Over 3,000 killer whales were taken by Soviet whalers, including an Antarctic
catch of 916 in 1979-80 alone, prompting the International Whaling Commission
to recommend a ban on commercial hunting of the species pending further research. Today, no country carries out a substantial hunt, although Indonesia
and Greenland
permit small subsistence hunts.
Killer whales have helped humans hunting other whales. One well-known example was in Eden, Australia
, including the male known as Old Tom. Whalers more often considered them a nuisance, however, as they would gather to scavenge meat from the whalers' catch. Some populations, such as in Alaska's Prince William Sound
, may have been reduced significantly by whalers shooting them in retaliation.
The killer whale's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquariums and aquatic theme parks. From 1976 to 1997, 55 whales were taken from the wild in Iceland, 19 from Japan, and three from Argentina. These figures exclude animals that died during capture. Live captures fell dramatically in the 1990s, and by 1999, about 40% of the 48 animals on display in the world were captive–born.
Organizations such as the World Society for the Protection of Animals
and the Whale and Dolphin Conservation Society
campaign against the practice of keeping them in captivity. In captivity they often develop pathologies, such as the dorsal fin
collapse seen in 60–90% of captive males. Captives have vastly reduced life expectancies, on average only living into their 20s. In the wild, females who survive infancy live 50 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 30 years on average, and up to 50–60 years. Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild. Critics claim that captive life is stressful due to these factors and the requirement to perform circus tricks that are not part of wild killer whale behavior. Wild killer whales travel up to 160 kilometres (99.4 mi) each day, and critics say that the animals are too big and intelligent to be suitable for captivity.
Captives occasionally act aggressively towards themselves, their tankmates, or humans, which critics say is a result of stress
. Tilikum
, a captive killer whale born in the wild, has been involved in three fatalities including one in which he grabbed a trainer and pulled her underwater, eventually drowning her. Experts are divided as to whether the injuries and deaths caused by captive killer whales have been accidents or deliberate attempts to cause harm.
Toothed whale
The toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.-Anatomy:Toothed whales have a single blowhole on the top of the head...
belonging to the oceanic dolphin
Oceanic dolphin
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
family. Killer whales are found in all oceans, from the frigid Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
and Antarctic regions to tropical seas. Killer whales as a species have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
s such as sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
s, seals
Earless seal
The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, Pinnipedia. All true seals are members of the family Phocidae . They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae...
, walrus
Walrus
The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...
es and even large whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s. Killer whales are regarded as apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
s, lacking natural predators and preying on even large sharks.
Killer whales are highly social
Social animal
A social animal is a loosely defined term for an organism that is highly interactive with other members of its species to the point of having a recognizable and distinct society.All mammals are social to the extent that mothers and offspring bond...
; some populations are composed of matrilineal family groups which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been described as manifestations of culture
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...
.
The IUCN currently assesses the orca's conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
as data deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
because of the likelihood that one or more killer whale types are separate species. Some local populations are considered threatened
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
or endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
due to prey depletion, habitat loss, pollution (by PCBs
Polychlorinated biphenyl
Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...
), capture for marine mammal parks, and conflicts with fisheries
Fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
. In late 2005, the killer whales known as the "southern resident killer whales
Southern Resident Killer Whales
The Southern Resident Killer Whales represent the smallest of four resident communities within the eastern North Pacific Ocean. It is the only Killer Whale population listed as endangered by the U.S. Fish & Wildlife Service...
" were placed on the U.S. Endangered Species list.
Wild killer whales are not considered a threat to humans, although there have been cases of captives killing or injuring their handlers at marine theme parks
Marine mammal park
A marine mammal park is a commercial theme park or aquarium where marine mammals such as dolphins, beluga whales and sea lions are kept within water tanks and displayed to the public in special shows. A marine mammal park is more elaborate than a dolphinarium, because it also features other marine...
. Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers.
Taxonomy and evolution
Orcinus orca is the only recognized extant species in the genus Orcinus, one of many animal species originally described by LinnaeusCarolus Linnaeus
Carl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in 1758 in Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
. Konrad Gessner wrote the first scientific description of a killer whale in his "Fish book" of 1558, based on examination of a dead stranded
Beached whale
A beached whale is a whale that has stranded itself on land, usually on a beach. Beached whales often die due to dehydration, the body collapsing under its own weight, or drowning when high tide covers the blowhole.-Species:...
animal in the Bay of Greifswald
Bay of Greifswald
The Bay of Greifswald is a basin in the southwestern Baltic Sea, off the shores of Germany in the state of Mecklenburg-Vorpommern. With an area of 514 km², it is the largest Bodden of the German Baltic coast....
that had attracted a great deal of local interest.
The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The killer whale lineage probably branched off shortly thereafter. Although it has morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similarities with the pygmy killer whale
Pygmy Killer Whale
The pygmy killer whale is a small, rarely seen cetacean of the oceanic dolphin family . It derives its common name from sharing some physical characteristics with the orca It is the smallest species that has "whale" in its common name. In fact, "killer" may be more apt in the case of the pygmy...
, the false killer whale
False Killer Whale
The False Killer Whale is a cetacean, and the third largest member of the oceanic dolphin family . It lives in temperate and tropical waters throughout the world. As its name implies, the False Killer Whale shares characteristics, such as appearance, with the more widely known Orca...
and the pilot whale
Pilot whale
Pilot whales are cetaceans belonging to the genus Globicephala. There are two extant species, the long-finned pilot whale and the short-finned pilot whale . The two are not readily distinguished at sea and analysis of the skulls is the best way to tell the difference between them...
s, a study of cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins
Orcaella
The snubfin dolphins are a genus of dolphins containing two members: the Irrawaddy Dolphin and Australian Snubfin Dolphin. The genus was long believed to be monotypic with the only species being the Irrawaddy Dolphin; however, in 2005, genetic analysis showed that the Australian Snubfin Dolphin is...
of the genus Orcaella.
Common names
English-speaking scientists most often use the term killer whale, although the term orca is increasingly used. Killer whale advocates point out that it has a long heritage. Indeed, the genus name Orcinus means "of the kingdom of the dead", or "belonging to OrcusOrcus
Orcus was a Roman god of the underworld.Orcus can also refer to:* Orcus , a demon prince in the Dungeons & Dragons role-playing game*90482 Orcus, a Trans-Neptunian object* Orcus , a genus of ladybird...
."
Ancient Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
originally applied orca (plural orcae) to these animals, possibly borrowing it from the Greek , which referred (among other things) to a whale species. Since the 1960s, orca has steadily grown in popularity; both names are now used. The term orca is preferred by some to avoid the negative connotations of "killer", and because, being part of the family Delphinidae, the species is more closely related to other dolphins than to whales.
They are sometimes referred to as blackfish, a name used for some whale species as well. Grampus is a former name for the species, but is now seldom used. This meaning of grampus should not be confused with the Grampus genus, whose only member is Risso's Dolphin
Risso's Dolphin
Risso's dolphin is the only species of dolphin in the genus Grampus.-Taxonomy:Risso's dolphin is named after Antoine Risso, whose description formed the basis of the first public description of the animal, by Georges Cuvier, in 1812...
.
Types
There are three to five types of killer whales that may be distinct enough to be considered different racesRace (biology)
In biology, races are distinct genetically divergent populations within the same species with relatively small morphological and genetic differences. The populations can be described as ecological races if they arise from adaptation to different local habitats or geographic races when they are...
, subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, or possibly even species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. The IUCN reported in 2008, "The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years." In the 1970s and 1980s, research off the west coast of Canada and the United States identified the following three types:
- Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. Residents' diet consists primarily of fish and sometimes squidSquidSquid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
, and they live in complex and cohesive family groups called pods. Female residents characteristically have a rounded dorsal fin tip that terminates in a sharp corner. They visit the same areas consistently. British ColumbiaBritish ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
and Washington resident populations are amongst the most-intensively studied marine mammals. Researchers have identified and named over 300 killer whales over the past 30 years. - Transient: The diet of these whales consists almost exclusively of marine mammals; they do not eat fish. Transients generally travel in small groups, usually of two to six animals, and have less persistent family bonds than residents. Transients vocalize in less variable and less complex dialects. Female transients are characterized by more triangular and pointed dorsal fins than those of residents. The gray or white area around the dorsal fin, known as the "saddle patch", often contains some black colouring in residents. However, the saddle patches of transients are solid and uniformly gray. Transients roam widely along the coast; some individuals have been sighted in both southern Alaska and California.
- Offshore: A third population of killer whales in the northeast Pacific was discovered in 1988, when a humpback whale researcher observed them in open water. As their name suggests, they travel far from shore and feed primarily on schoolingShoaling and schoolingIn biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
fish. However, because of the large, scarred and nicked dorsal fins resembling those of mammal-hunting transients, they may also eat mammals and sharks. They have mostly been encountered off the west coast of Vancouver IslandVancouver IslandVancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
and near the Queen Charlotte IslandsQueen Charlotte IslandsHaida Gwaii , formerly the Queen Charlotte Islands, is an archipelago on the North Coast of British Columbia, Canada. Haida Gwaii consists of two main islands: Graham Island in the north, and Moresby Island in the south, along with approximately 150 smaller islands with a total landmass of...
. Offshores typically congregate in groups of 20–75, with occasional sightings of larger groups of up to 200. Currently, little is known about their habits, but they are genetically distinct from residents and transients. Offshores appear to be smaller than the others, and females are characterized by dorsal finDorsal finA dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
tips that are continuously rounded.
Other populations have not been as well studied, although specialized fish-eating and mammal-eating killer whales have been distinguished elsewhere. Separate populations of fish-eating and mammal-eating killer whales have been identified around the United Kingdom. Fish-eating killer whales in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
have resident-like social structures, while mammal-eating killer whales in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
and the Crozet Islands
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
behave more like transients.
Three types have been documented in the Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
. Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers are skeptical about their status, and it is difficult to link these directly to the types described below.
- Type A looks like a "typical" killer whale, a large, black and white form with a medium-sized white eye patch, living in open water and feeding mostly on minke whaleMinke WhaleMinke whale , or lesser rorqual, is a name given to two species of marine mammal belonging to a clade within the suborder of baleen whales. The minke whale was given its official designation by Lacepède in 1804, who described a dwarf form of Balænoptera acuto-rostrata...
s. - Type B is smaller than Type A. It has a large white eye patch. Most of the dark parts of its body are medium gray instead of black, although it has a dark gray patch called a "dorsal cape" stretching back from its forehead to just behind its dorsal fin. The white areas are stained slightly yellow. It feeds mostly on sealsPinnipedPinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
. - Type C is the smallest type and lives in larger groups than the others. Its eye patch is distinctively slanted forwards, rather than parallel to the body axis. Like Type B, it is primarily white and medium gray, with a dark gray dorsal cape and yellow-tinged patches. Its only observed prey is the Antarctic CodAntarctic codThe Antarctic cod, or Antarctic toothfish, of the fish family Nototheniidae, is famous for producing antifreeze glycoprotein that allows it to survive in the ice-laden waters of the Southern Ocean surrounding Antarctica...
. - Type D was identified based on photographs of a 1955 mass stranding in New Zealand and six at-sea sightings since 2004. Immediately recognizable by its extremely small white eye patch, shorter than usual dorsal fin, and bulbous head (similar to a pilot whale). Its geographic range appears to be circumglobal in subantarctic waters between latitudes 40°S and 60°S. And although nothing is known about the Type D diet, it is suspected to include fish because groups have been photographed around longline vessels where they reportedly depredate Patagonian toothfish (Dissostichus eleginoides).
Types B and C live close to the ice pack, and diatoms in these waters may be responsible for the yellowish coloring of both types. Mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
sequences support the theory that these are separate species that have recently diverged. More recently, complete mitochondrial sequencing indicates that the two Antarctic groups that eat seals and fish should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.
Research is ongoing into the genetic relationships among killer whale types, and whether the types that have been identified represent deep evolutionary trends. For example, it was long thought that mammal-eating killer whales were likely to be closely related to other mammal-eating killer whales from different regions, but genetic testing refuted this hypothesis.
Description
False Killer Whale
The False Killer Whale is a cetacean, and the third largest member of the oceanic dolphin family . It lives in temperate and tropical waters throughout the world. As its name implies, the False Killer Whale shares characteristics, such as appearance, with the more widely known Orca...
or Risso's dolphin
Risso's Dolphin
Risso's dolphin is the only species of dolphin in the genus Grampus.-Taxonomy:Risso's dolphin is named after Antoine Risso, whose description formed the basis of the first public description of the animal, by Georges Cuvier, in 1812...
. The killer whale's teeth are very strong and covered in enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
. Its jaws are a powerful gripping apparatus, as the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The front teeth are inclined slightly forward and outward, thus allowing the killer whale to withstand powerful jerking movements from its prey while the middle and back teeth hold it firmly in place.
Killer whales are the largest extant members of the dolphin family. Males typically range from 6 to 8 m (19.7 to 26.2 ) long and weigh in excess of 6 tonnes (5.9 LT). Females are smaller, generally ranging from 5 to 7 m (16.4 to 23 ) and weighing about 3 to 4 t (3 to 3.9 ). The largest male killer whale on record was 9.8 metres (32.2 ft), weighing over 10 tonnes (9.8 LT), while the largest female was 8.5 metres (27.9 ft), weighing 7.5 tonnes (7.4 LT). Calves at birth weigh about 180 kilograms (396.8 lb) and are about 2.4 metres (7.9 ft) long. The killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (58.8 km/h). The skeleton of the killer whale is of the typical delphinid structure but is more robust in all respects. The killer whale's integument, unlike that of most other dolphin species, is characterised by a well-developed dermal layer with a dense network of fascicle
Muscle fascicle
In anatomy, a fascicle is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue.Specialized muscle fibers in the heart that transmit electrical impulses from the Atrioventricular Node to the Purkinje Fibers are fascicles, also referred to as bundle branches...
s of collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
fibers.
Killer whale pectoral fins are large and rounded, resembling paddles. Males have significantly larger pectoral fins than females. At about 1.8 metres (5.9 ft) the male's dorsal fin is more than twice the size of the female's and is more of a triangular shape—a tall, elongated isosceles triangle—whereas hers is shorter and more curved. Males and females also have different patterns of black and white skin in the genital area. Sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
is also apparent in the skull; adult males have a longer lower jaw than females, and have a larger occipital crest.
Individual killer whales can often be identified from the dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals. Photo identification has enabled the local population of killer whales to be counted each year rather than estimated and has enabled great insight into lifecycles and social structures.
White killer whales occur sporadically among normal killer whales, but are rare. They have been spotted in the northern Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
and around St. Lawrence Island
St. Lawrence Island
St. Lawrence Island is located west of mainland Alaska in the Bering Sea, just south of the Bering Strait, at about 63°30' North 173°20' West. The village of Gambell is located on the northwest cape, from the Chukchi Peninsula in the Russian Far East. The island is part of Alaska, but closer to...
, and near the Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n coast. In February 2008, a white killer whale was photographed 2 miles (3.2 km) off Kanaga
Kanaga Island
Kanaga Island is a part of the Andreanof Islands group of the Aleutian Islands in Alaska. The island measures roughly 30 miles long and between 4 and 8 miles wide with an area of 142 sq mi , making it the 42nd largest island in the United States...
Volcano.
Killer whales have good eyesight above and below the water, excellent hearing, and a good sense of touch. They have exceptionally sophisticated echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
abilities, detecting the location and characteristics of prey and other objects in their environment by emitting clicks and listening for echoes.
Life cycle
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
varies from 15 to 18 months. Mothers calve, with usually a single offspring, about once every 5 years. In resident pods, birth occurs at any time of year, although winter is the most popular. Mortality is extremely high during the first six to seven months of life, when 37–50% of all calves die. Weaning
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...
begins at about 12 months and completes by the age of two. According to observations in several regions, all male and female killer whale pod members participate in the care of the young. Killer Whales and Pilot whales are the only species in which the females go through menopause and live for decades after they have finished breeding. Killer whales are unique among cetaceans, as their heads become shorter as they age.
Females breed until age 40, meaning that on average they raise five offspring. The lifespan of wild females averages 50 years, with a maximum of 80–90 years. Males sexually mature at the age of 15 but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of 50–60 years. One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia. This would have made him up to 90 years old. Examination of his teeth indicated he died around age 35, but this method of age determination is now believed to be inaccurate for older animals. One male well known to researchers in the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
called Ruffles (J1) was estimated to have been born in 1951, making him 59 years old when he died in 2010. Captive killer whale lifespans are typically significantly shorter, usually less than 25 years; however, numerous individuals are alive in their thirties, and a few have reached their 40s. In many instances, the lifespans of killer whales depend on the will of the animal.
Range and habitat
Pelagic zone
Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...
environments.
Systematic surveys indicate the highest densities of killer whales (>0.40 individuals per 100 km²) in the northeast Atlantic around the Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
coast, in the north Pacific along the Aleutian Islands, the Gulf of Alaska
Gulf of Alaska
The Gulf of Alaska is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the east, where Glacier Bay and the Inside Passage are found.The entire shoreline of the Gulf is...
and in the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
off much of the coast of Antarctica. They are considered "common" (0.20–0.40 individuals per 100 km²) in the eastern Pacific along the coasts of British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, Washington and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, in the North Atlantic Ocean around Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and the Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
. High densities have also been reported but not quantified in the western North Pacific around the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
, Sea of Okhotsk
Sea of Okhotsk
The Sea of Okhotsk is a marginal sea of the western Pacific Ocean, lying between the Kamchatka Peninsula on the east, the Kuril Islands on the southeast, the island of Hokkaidō to the far south, the island of Sakhalin along the west, and a long stretch of eastern Siberian coast along the west and...
, Kuril Islands
Kuril Islands
The Kuril Islands , in Russia's Sakhalin Oblast region, form a volcanic archipelago that stretches approximately northeast from Hokkaidō, Japan, to Kamchatka, Russia, separating the Sea of Okhotsk from the North Pacific Ocean. There are 56 islands and many more minor rocks. It consists of Greater...
, Kamchatka and the Commander Islands and in the southern hemisphere off the coasts of South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
, Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
, off the coast of southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
and the tip of southern Africa
Southern Africa
Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...
. They are reported as seasonally common in the Canadian Arctic, including Baffin Bay
Baffin Bay
Baffin Bay , located between Baffin Island and the southwest coast of Greenland, is a marginal sea of the North Atlantic Ocean. It is connected to the Atlantic via Davis Strait and the Labrador Sea...
between Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
and Nunavut
Nunavut
Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999, via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...
, and around Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
and Macquarie Island
Macquarie Island
Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage...
. Information for offshore regions and tropical waters is more scarce, but widespread, if not frequent, sightings indicate that the killer whale can survive in most water temperatures. There have been sightings, for example, in the Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
, the Arabian
Arabian Sea
The Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by the Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui in northeastern Somalia and Kanyakumari in India...
Sea, the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
and the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
around the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....
.
Probably the largest population lives in Antarctic waters, where they range up to the edge of the pack ice and are believed to venture into the denser pack ice, finding open leads
Lead (sea ice)
Leads are stretches of open water within fields of sea ice. Leads are caused by movements of the ice due to wind, or to currents in the underlying water, and may open and close again within a brief period; alternatively they may remain open more or less permanently...
much like beluga whales in the Arctic. In contrast, killer whales are seasonal summer visitors to Arctic waters, where they do not approach the ice pack. With the rapid Arctic sea ice decline in the Hudson Strait
Hudson Strait
Hudson Strait links the Atlantic Ocean to Hudson Bay in Canada. It lies between Baffin Island and the northern coast of Quebec, its eastern entrance marked by Cape Chidley and Resolution Island. It is long...
, their range now extends deep into the northwest Atlantic.
Migration patterns are poorly understood. Each summer, the same individuals appear off the coasts of British Columbia and Washington State. Despite decades of research, where these animals go for the rest of the year remains unknown. Transient pods have been sighted from southern Alaska to central California. Resident killer whales sometimes travel as much as 160 kilometres (99.4 mi) in a day, but may be seen in a general area for a month or more. Resident killer whale pod ranges vary from 320 to 1300 km (198.8 to 807.8 ).
Occasionally, killer whales swim into freshwater rivers. They have been documented 100 miles (160.9 km) up the Columbia River
Columbia River
The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...
in the United States. They have also been found in the Fraser River
Fraser River
The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Mount Robson in the Rocky Mountains and flowing for , into the Strait of Georgia at the city of Vancouver. It is the tenth longest river in Canada...
in Canada and the Horikawa River
Horikawa River
The flows north to south through Nagoya, Aichi Prefecture, Japan, and is part of the Shōnai River system.-History:The river is a man-made canal excavated in 1610 by order of Fukushima Masanori to allow ships to bring goods to the city...
in Japan.
Population
Worldwide population estimates are uncertain, but recent consensus suggest an absolute minimum of 50,000. Local estimates include roughly 25,000 in the Antarctic, 8,500 in the tropical Pacific, 2,250–2,700 off the cooler northeast Pacific and 500–1,500 off Norway. Japan's Fisheries Agency estimated there were 2,321 killer whales in the seas around Japan.Feeding
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
sea specialize in herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
and follow that fish's autumnal migration to the Norwegian coast. Other populations prey on seals. Salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
account for 96% of northeast Pacific residents' diet. 65% of them are large, fatty Chinook
Chinook salmon
The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon...
. Chum salmon are also eaten, but smaller sockeye and pink salmon are not a significant food item. Depletion of specific prey species in an area is therefore cause for concern for local populations, despite the high diversity of prey. On average, a killer whale eats 227 kilograms (500.4 lb) each day.
Because some killer whales prey on large whales and shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, they are considered to be apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
s. They are sometimes called the wolves of the sea, because they hunt in groups like wolf packs.
Fish and other cold-blooded prey
Fish-eating killer whales prey on around 30 species of fish, particularly Chinook, salmon, herring, and tunaTuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...
. In New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, rays
Rajiformes
Rajiformes is one of the four orders of batoids, flattened cartilaginous fishes related to sharks.Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion...
are killer whales' most frequent prey, and they have also been observed hunting shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s (particularly makos, threshers
Thresher shark
Thresher sharks are large lamniform sharks of the family Alopiidae. Found in all temperate and tropical oceans of the world, the family contains three species all within the genus Alopias.-Taxonomy:...
and smooth hammerhead
Smooth hammerhead
The smooth hammerhead is a species of hammerhead shark, family Sphyrnidae, so named because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape , without an indentation in the middle of the front margin...
s). Squid and sea turtles are also taken.
Carousel feeding
Carousel feeding refers to the hunting technique commonly employed by orcas. An individual or small group of orcas will release bursts of bubble or flash their white undersides to round prey such as salmon or herring into a tight defensive ball close to the surface. The orcas then slap the ball...
: the killer whales force the herring into a tight ball by releasing bursts of bubbles or flashing their white undersides. They then slap the ball with their tail flukes, either stunning or killing up to 10–15 at a time. The herring are then eaten one at a time. Carousel feeding has only been documented in the Norwegian killer whale population and with some oceanic dolphin species.
Killer whales can induce tonic immobility
Tonic immobility
Apparent death, colloquially known as playing dead or playing possum, is an antipredator behavior observed in a wide range of animals in which they take on the appearance of being dead to an observer...
in sharks and rays by holding them upside down, rendering them helpless and incapable of injuring the whale. Some sharks suffocate within about 15 minutes while the whale holds them still, because these sharks need to move to breathe. In one incident filmed near the Farallon Islands
Farallon Islands
The Farallon Islands, or Farallones , are a group of islands and sea stacks in the Gulf of the Farallones, off the coast of San Francisco, California, USA. They lie outside the Golden Gate and south of Point Reyes, and are visible from the mainland on clear days...
, a female killed a 3 – long great white shark
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...
, apparently after swimming with it upside-down in her mouth and inducing tonic immobility in it. She and another pod member ate the shark's liver and allowed the rest of the carcass to sink.
In July 1992, two killer whales attacked, killed and fed on an 8 metres (26.2 ft) long whale shark
Whale shark
The whale shark, Rhincodon typus, is a slow-moving filter feeding shark, the largest extant fish species. The largest confirmed individual had a length of and a weight of more than , but unconfirmed claims report considerably larger whale sharks...
, Rhincodon typus, in the waters off Bahia de los Angeles in Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
.
Mammal prey
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
contents, scar
Scar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
ring on the prey's body, or feeding activity. Groups even attack larger cetaceans such as minke whale
Minke Whale
Minke whale , or lesser rorqual, is a name given to two species of marine mammal belonging to a clade within the suborder of baleen whales. The minke whale was given its official designation by Lacepède in 1804, who described a dwarf form of Balænoptera acuto-rostrata...
s, gray whale
Gray Whale
The gray whale, Eschrichtius robustus, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of about , a weight of , and lives 50–70 years. The common name of the whale comes from the gray patches and white mottling on its dark skin. Gray whales were...
s, and rarely sperm whale
Sperm Whale
The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...
s or blue whale
Blue Whale
The blue whale is a marine mammal belonging to the suborder of baleen whales . At in length and or more in weight, it is the largest known animal to have ever existed....
s.
Hunting large whales usually takes several hours. Killer whales generally choose to attack young or weak animals instead. However, a group of five or more may attack a healthy adult. When hunting a young whale, a group chases it and its mother until they wear out. Eventually they separate the pair and surround the calf, preventing it from surfacing to breathe, drowning it. Pods of female sperm whales sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using them to repel the attackers. Rarely, large killer whale pods can overwhelm even adult female sperm whales. Adult bull sperm whales, which are large, powerful and aggressive when threatened, and fully-grown adult blue whales, who are possibly too large to overwhelm, are not believed to be predated by killer whales.
Other marine mammal prey species include most species of seal
Earless seal
The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, Pinnipedia. All true seals are members of the family Phocidae . They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae...
, sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
and fur seal
Fur seal
Fur seals are any of nine species of pinnipeds in the Otariidae family. One species, the northern fur seal inhabits the North Pacific, while seven species in the Arctocephalus genus are found primarily in the Southern hemisphere...
. Walrus
Walrus
The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...
es and sea otter
Sea Otter
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...
s are less frequently taken. Often, to avoid injury, killer whales 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. Sea lions are killed by head-butting or after a stunning blow from a tail fluke. In the Aleutian Islands, a decline in sea otter
Sea Otter
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...
populations in the 1990s was controversially attributed by some scientists to killer whale predation, although there is no direct evidence of this. The decline of sea otters followed a decline in harbour seal and Steller sea lion populations, the killer whale's preferred prey, which in turn may be substitutes for their original prey, now decimated by industrial whaling.
In steeply banked beaches off Península Valdés, Argentina, and the Crozet Islands
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
, killer whales feed on South American sea lion
South American Sea Lion
The South American sea lion , also called the southern sea lion and the Patagonian sea lion, is a sea lion found on the Chilean, Peruvian, Uruguayan, Argentine and Southern Brazilian coasts. It is the only member of the genus Otaria...
s and southern elephant seal
Southern Elephant Seal
The Southern Elephant Seal is one of the two extant species of elephant seal. It is both the most massive pinniped and member of the order Carnivora living today...
s in shallow water, even beaching
Beached whale
A beached whale is a whale that has stranded itself on land, usually on a beach. Beached whales often die due to dehydration, the body collapsing under its own weight, or drowning when high tide covers the blowhole.-Species:...
temporarily to grab prey before wriggling back to the sea. Beaching, usually fatal to cetaceans, is not an instinctive behavior, and can require years of practice for the young.
Weddell Seal
The Weddell seal , is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. Weddell seals have the most southerly distribution of any mammal, with a habitat that extends as far south as McMurdo Sound...
s, Ross seals
Ross Seal
The Ross seal is a true seal with a range confined entirely to the pack ice of Antarctica. It is the only species of the genus Ommatophoca. First described during James Clark Ross' British Antarctic Expedition in 1841, it is the smallest, least abundant and least well known of the Antarctic...
, crabeater seal
Crabeater Seal
The crabeater seal, Lobodon carcinophagus, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium to large-sized , relatively slender and pale-colored, found primarily on the free floating pack ice that extends seasonally out from the Antarctic coast, which...
s and leopard seal
Leopard Seal
The leopard seal , also referred to as the sea leopard, is the second largest species of seal in the Antarctic...
s resting on ice floes and then swim in groups to create waves that wash over the floe. This washes the seal into the water where other killer whales lie in wait.
Killer whales have also been observed preying on terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
mammals, such as deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
and moose
Moose
The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...
swimming between islands off the northwest coast of North America. Killer whale cannibalism
Cannibalism (zoology)
In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species...
has also been reported based on analysis of stomach contents, but this is likely to be the result of scavenging remains dumped by whalers. One killer whale was also attacked by its companions after being shot. Although resident killer whales have never been observed to eat other marine mammals, they occasionally harass and kill porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
s and seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
for no apparent reason.
Birds
Killer whales in many areas prey on several bird species, including penguinPenguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s, cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s and gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s. A captive killer whale at MarineLand
Marineland
Marineland can refer to multiple places:*Marineland of Florida, an oceanarium in Florida**Marineland, Florida, the community where the oceanarium is located*MarineLand, an oceanarium/amusement park in Niagara Falls, Ontario, Canada...
discovered that it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Four other killer whales then learned to copy the behavior.
Behavior
Resident killer whales swim with porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
s, other dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s, seals
Earless seal
The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, Pinnipedia. All true seals are members of the family Phocidae . They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae...
, and sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
s, which are common prey for transient killer whales.
Social structure
Killer whales are notable for their complex societies. Only elephantElephant
Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...
s and higher primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s, such as humans, live in comparably complex social structures. Due to orcas' complex social bonds and society, many marine experts have concerns about how humane it is to keep these animals in captive situations. Resident killer whales in the eastern North Pacific have a particularly complex and stable social grouping system. Unlike any other mammal species whose social structure is known, residents live with their mothers for their entire lives. These societies are based on matrilines consisting of the matriarch and her descendants who form part of the line, as do their descendants. The average size of a matriline is 5.5 animals.
Because females can reach age 90, as many as four generations travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. With one exception, the killer whale named Luna
Luna (Orca)
Luna also known as L98 or Tsuux'iit, was a killer whale born in Puget Sound. After being separated from his mother as a toddler, Luna spent five years in Nootka Sound, off the west coast of Vancouver Island.Although Luna was healthy and his presence in the area delighted tourists and drew a large...
, no permanent separation of an individual from a resident matriline has been recorded.
Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may separate for weeks or months at a time. DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
testing indicates that resident males nearly always mate with females from other pods.
The final association layer, perhaps more arbitrarily defined than the familial groupings, is called the community and is defined as a set of clans that regularly commingle. Clans within a community do not share vocal patterns.
Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mothers than females. These bonds can extend well into adulthood. Unlike residents, extended or permanent separation of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become “rovers” and do not form long-term associations, occasionally joining groups that contain reproductive females. As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted.
Vocalizations
Like all cetaceans, killer whales depend heavily on underwater sound for orientation, feeding, and communication. Killer whales produce three categories of sounds: clicks, whistles, and pulsed calls. Clicks are believed to be used primarily for navigation and discriminating prey and other objects in the surrounding environment, but are also commonly heard during social interactions.Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters. Residents feed primarily on salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
, whose hearing is too poor to detect killer whale calls at any relevant distance. Residents make sounds to identify themselves when they approach another marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
.
Transient are typically silent probably to avoid alerting their mammalian prey, all of whom have excellent underwater hearing. They sometimes use a single click (called a cryptic click) rather than the long train of clicks observed in other populations.
All members of a resident pod use similar calls, known collectively as a dialect. Dialects are composed of specific numbers and types of discrete, repetitive calls. They are complex and stable over time. Call patterns and structure are distinctive within matrilines. Newborns produce calls similar to their mothers, but have a more limited repertoire. Individuals likely learn their dialect through contact with their mother and other pod members. For instance, family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them. Dialects are probably an important means of maintaining group identity and cohesiveness. Similarity in dialects likely reflects the degree of relatedness between pods, with variation building over time.
Researchers have not determined whether calls have particular meanings or are associated with specific types of activity. Resident dialects contain 7–17 (mean = 11) distinctive call types. Transient dialects are much different, having only 4–6 discrete calls, none of which they share with residents. All members of the North American west coast transient community express the same basic dialect, although minor regional variation in call types is evident. Preliminary research indicates that offshore killer whales have group-specific dialects that are unlike those of residents and transients.
Intelligence
Killer whales have the second-heaviest brains among marine mammals. They can be trainedAnimal training
Animal training refers to teaching animals specific responses to specific conditions or stimuli. Training may be for the purpose of companionship, detection, protection, entertainment or all of the above....
in captivity and are often described as intelligent, although defining and measuring "intelligence" is difficult in a species whose environment and behavioral strategies are very different from those of humans.
Killer whales imitate others, and seem to deliberately teach skills to their kin. This is most strikingly seen when killer whales deliberately beach
Beached whale
A beached whale is a whale that has stranded itself on land, usually on a beach. Beached whales often die due to dehydration, the body collapsing under its own weight, or drowning when high tide covers the blowhole.-Species:...
themselves to catch seals. Off Península Valdés, adults sometimes pull seals off the shoreline and then release them again near juvenile whales, allowing the younger whales to practice the difficult capture technique on the now-weakened prey. Off the Crozet Islands
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
, mothers push their calves onto the beach, waiting to pull the youngster back if needed.
People who have interacted closely with killer whales offer numerous anecdotes
Anecdotal evidence
The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....
demonstrating the whales' curiosity, playfulness, and ability to solve problems. For example, Alaskan killer whales have not only learned how to steal fish from longlines, but have overcome a variety of techniques designed to stop them, such as the use of unbaited lines as decoys. Once, fishermen placed their boats several miles apart, taking turns retrieving small amounts of their catch, in the hope that the whales would not have enough time to move between boats to steal fish as it was being retrieved. A researcher described what happened next:
In other anecdotes, researchers describe incidents in which wild killer whales playfully tease humans by repeatedly moving objects that the humans are trying to reach, or suddenly start to toss around a chunk of ice after a human throws a snowball.
The killer whale's use of dialects and the passing of other learned behaviours from generation to generation have been described as a form of culture
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...
.
Conservation
In 2008, the IUCN changed its assessment of the killer whale's conservation statusConservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
from conservation dependent
Conservation Dependent
Conservation Dependent was an IUCN category assigned to species or lower taxa which were dependent on conservation efforts to prevent the taxon becoming threatened with extinction...
to data deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
, recognizing that one or more killer whale types may actually be separate, endangered species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Depletion of prey species, pollution, large-scale oil spill
Oil spill
An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters...
s, and habitat disturbance caused by noise and conflicts with boats are currently the most significant worldwide threats.
Like other animals at the highest trophic level
Trophic level
The trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism...
s, the killer whale is particularly at risk of poisoning from accumulation of toxins, including polychlorinated biphenyl
Polychlorinated biphenyl
Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...
s (PCBs). European Harbour seals have problems in reproductive and immune functions associated with high levels of PCBs and related contaminants, and a survey off the Washington coast found that PCB levels in killer whales were higher than levels that had caused health problems in harbour seals. Blubber samples in the Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
show higher levels of PCBs, pesticides and brominated flame-retardant
Brominated flame-retardant
Brominated flame retardants are organobromide compounds that have an inhibitory effect on the ignition of combustible organic materials. Of the commercialized chemical flame retardants, the brominated variety are most widely used. They are very effective in plastics and textile applications, e.g....
s than in polar bear
Polar Bear
The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...
s. When food is scarce, killer whales metabolize blubber
Blubber
Blubber is a thick layer of vascularized adipose tissue found under the skin of all cetaceans, pinnipeds and sirenians.-Description:Lipid-rich, collagen fiber–laced blubber comprises the hypodermis and covers the whole body, except for parts of the appendages, strongly attached to the musculature...
for energy, which increases pollutant concentrations.
In the Pacific Northwest, wild salmon stocks, a main resident food source, have declined dramatically in recent years. On the west coast of Alaska and the Aleutian Islands, seal and sea lion populations have also substantially declined.
Southern Resident Killer Whales
The Southern Resident Killer Whales represent the smallest of four resident communities within the eastern North Pacific Ocean. It is the only Killer Whale population listed as endangered by the U.S. Fish & Wildlife Service...
community as an endangered population under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. The southern resident community comprises three pods which live mostly in the Georgia
Strait of Georgia
The Strait of Georgia or the Georgia Strait is a strait between Vancouver Island and the mainland coast of British Columbia, Canada. It is approximately long and varies in width from...
and Haro Straits and Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
and Washington. They do not breed outside of their community, which was once estimated at around 200 animals and later shrank to around 90. In October 2008, the annual survey revealed that seven were missing and presumed dead, reducing the count to 83. This is potentially the largest decline in the population in the past ten years. These deaths can be attributed to declines in chinook salmon
Chinook salmon
The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon...
.
Noise from shipping, drilling, and other human activities is a significant concern in some key killer whale habitats, including Johnstone Strait
Johnstone Strait
Johnstone Strait is a channel along the north east coast of Vancouver Island in British Columbia, Canada. Opposite the Vancouver Island coast, running north to south, are Hanson Island, West Cracroft Island, the mainland British Columbia Coast, Hardwick Island, West Thurlow Island and East...
and Haro Strait
Haro Strait
Haro Strait, often referred to as the Haro Straits because it is really a series of straits, is one of the main channels connecting the Strait of Georgia to the Strait of Juan de Fuca, separating Vancouver Island and the Gulf Islands in British Columbia, Canada from the San Juan Islands of...
. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Killer whales also avoided the surrounding waters. High-intensity sonar used by the Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
disturbs killer whales along with other marine mammals. Killer whales are popular with whale watchers
Whale watching
Whale watching is the practice of observing whales and other cetaceans in their natural habitat. Whales are watched most commonly for recreation but the activity can also serve scientific or educational purposes. A 2009 study, prepared for IFAW, estimated that 13 million people went whale watching...
, which may stress the whales and alter their behavior, particularly if boats approach too closely or block their line of travel.
The Exxon Valdez oil spill
Exxon Valdez oil spill
The Exxon Valdez oil spill occurred in Prince William Sound, Alaska, on March 24, 1989, when the Exxon Valdez, an oil tanker bound for Long Beach, California, struck Prince William Sound's Bligh Reef and spilled of crude oil. It is considered to be one of the most devastating human-caused...
adversely affected killer whales in Prince William Sound
Prince William Sound
Prince William Sound is a sound off the Gulf of Alaska on the south coast of the U.S. state of Alaska. It is located on the east side of the Kenai Peninsula. Its largest port is Valdez, at the southern terminus of the Trans-Alaska Pipeline System...
and Alaska's Kenai Fjords region. Eleven members (about half) of one resident pod disappeared in the following year. The spill damaged salmon and other prey populations, which in turn damaged local killer whales. By 2009, scientists estimated the AT1 transient population (considered part of a larger population of 346 transients), numbered only 7 individuals and had not reproduced since the spill. This population is expected to die out.
Indigenous cultures
Indigenous peoples of the Pacific Northwest Coast
The Indigenous peoples of the Pacific Northwest Coast are the pre-Columbian inhabitants of the Pacific Northwest Coast, their descendants, and many ethnic groups who identify with those historical peoples. They are now situated within the Canadian Province of British Columbia and the U.S...
feature killer whales throughout their history, art, spirituality and religion. The Haida regarded killer whales as the most powerful animals in the ocean, and their mythology tells of killer whales living in houses and towns under the sea. According to these myths, killer whales took on human form when submerged, and humans who drowned went to live with them. For the Kwakwaka'wakw
Kwakwaka'wakw
The Kwakwaka'wakw are an Indigenous group of First Nations peoples, numbering about 5,500, who live in British Columbia on northern Vancouver Island and the adjoining mainland and islands.Kwakwaka'wakw translates as "Those who speak Kwak'wala", describing the collective nations within the area that...
, the killer whale was regarded as the ruler of the undersea world, with sea lion
Sea Lion
Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...
s for slaves and dolphins for warriors. In Kwakwaka'wakw and Nuu-chah-nulth mythology, killer whales may embody the souls of deceased chiefs. The Tlingit of southeastern Alaska regarded the killer whale as custodian of the sea and a benefactor of humans.
The Maritime Archaic
Maritime Archaic
The Maritime Archaic is a North American cultural complex of the Late Archaic along the coast of Newfoundland, the Canadian Martimes and northern New England. The Maritime Archaic began in approximately 7000 BC and lasted into the 18th century. The culture consisted of sea-mammal hunters in the...
people of Newfoundland also had great respect for killer whales, as evidenced by stone carvings found in a 4,000-year-old burial site at the Port au Choix
Port au Choix
Port au Choix or Port aux Choix is a town in the Canadian province of Newfoundland and Labrador. The nearest airport is Port au Choix Airport, 2.8 km to the southeast.- History :...
National Historic Site.
In the tales and beliefs of the Siberian Yupik
Siberian Yupik
Siberian Yupiks, or Yuits, are indigenous people who reside along the coast of the Chukchi Peninsula in the far northeast of the Russian Federation and on St. Lawrence Island in Alaska. They speak Central Siberian Yupik , a Yupik language of the Eskimo–Aleut family of languages.They were also...
people, killer whales are said to appear as wolves in winter, and wolves as killer whales in summer. Killer whales are believed to assist their hunters in driving walrus. Reverence is expressed in several forms: the boat represents the animal, and a wooden carving hung from the hunter's belt. Small sacrifice
Sacrifice
Sacrifice is the offering of food, objects or the lives of animals or people to God or the gods as an act of propitiation or worship.While sacrifice often implies ritual killing, the term offering can be used for bloodless sacrifices of cereal food or artifacts...
s such as tobacco are strewn into the sea for them. Killer whales were believed to have helped the hunters even when in wolf guise, by forcing reindeer to allow themselves to be killed.
"Killer" stereotype
In Western cultureWestern culture
Western culture, sometimes equated with Western civilization or European civilization, refers to cultures of European origin and is used very broadly to refer to a heritage of social norms, ethical values, traditional customs, religious beliefs, political systems, and specific artifacts and...
s, killer whales were historically feared as dangerous, savage predators. The first written description of a killer whale was given by Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
in circa AD 70, who wrote, "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."
There have been very few confirmed attacks on humans by wild killer whales, none of which has been fatal. In one instance, killer whales tried to tip ice floes on which a dog team and photographer of the Terra Nova Expedition
Terra Nova Expedition
The Terra Nova Expedition , officially the British Antarctic Expedition 1910, was led by Robert Falcon Scott with the objective of being the first to reach the geographical South Pole. Scott and four companions attained the pole on 17 January 1912, to find that a Norwegian team led by Roald...
was standing. There is speculation that the sled dogs' barking may have sounded enough like seal calls to trigger the killer whale's hunting curiosity. In the 1970s, a surfer in California was bitten, and in 2005 a boy in Alaska who was splashing in a region frequented by harbor seals was bumped by a killer whale that apparently misidentified him as prey. Unlike wild killer whales, captive killer whales are reported to have made nearly two dozen attacks on humans
Orca attacks on humans
Killer whales are powerful predators capable of dispatching prey much larger than humans, such as leopard seals and great white sharks. They have also been recorded preying on usually terrestrial species such as moose swimming between islands...
since the 1970s, some of which have been fatal.
Competition with fishermen also led to killer whales being regarded as pests. In the waters of the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
and Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
, the shooting of killer whales was accepted and even encouraged by governments. As an indication of the intensity of shooting that occurred until fairly recently, about 25% of the killer whales captured in Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
for aquaria through 1970 bore bullet scars. The U.S. Navy claimed to have deliberately killed hundreds of killer whales in Icelandic waters in 1956.
Modern Western attitudes
Western attitudes towards killer whales have changed dramatically in recent decades. In the mid 1960s and early 1970s, killer whales came to much greater public and scientific awareness, starting with the first live-capture and display of a killer whale known as Moby DollMoby Doll
Moby Doll was the first captive orca displayed in a public aquarium exhibit.The 15 foot long, 1-ton male was captured in 1964 near East Point, Saturna Island in British Columbia. A sculptor, Samuel Burich, had been commissioned by the Vancouver Aquarium to kill an orca in order to construct a...
, a resident that had been harpooned off Saturna Island
Saturna Island
Saturna Island is a mountainous island, about 31 km² in size, in the Southern Gulf Islands chain of British Columbia. It is situated approximately midway between the Lower Mainland of B.C. and Vancouver Island, and is the most easterly of the Gulf Islands. It is surrounded on three sides by...
in 1964. So little was known at the time that it was nearly two months before the whale's keepers discovered what food (fish) it was willing to eat. To the surprise of those who saw him, Moby Doll was a docile, non-aggressive whale that made no attempts to attack humans.
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
, and public interest in the animals grew. Millions of people became interested in killer whales after viewing them in captivity. In the 1970s, research pioneered by Michael Bigg
Michael Bigg
Michael Bigg was a Canadian marine biologist who is recognized as the founder of modern research on killer whales. With his colleagues, he developed new techniques for studying killer whales and conducted the first population census of the animals...
led to the discovery of the species' complex social structure, its use of vocal communication, and its extraordinarily stable mother-offspring bonds. Through photo-identification
Wildlife photo-identification
Photo-identification is a technique used into identify and track individuals of a wild animal study population over time. It relies on capturing photographs of distinctive characteristics such as skin patterns and scars from the animal...
techniques, individuals were named and tracked over decades.
Bigg's techniques also revealed that the Pacific Northwest population was small—in the low hundreds rather than the thousands that had been previously assumed. The Southern Resident community alone had lost 48 of its members to captivity; by 1976, only 80 remained. In the Pacific Northwest, the species that had unthinkingly been targeted became a cultural icon within a few decades.
The public's growing appreciation also led to growing opposition to whale–keeping in aquaria. Only one whale has been taken in North American waters since 1976. In recent years, the extent of the public's interest in killer whales has manifested itself in several high-profile efforts surrounding individuals. Following the success of the 1993 film Free Willy
Free Willy
Free Willy is a 1993 family film directed by Simon Wincer, and released by Warner Bros. under its Family Entertainment label. The film stars Jason James Richter as a young boy who befriends an orca whale, named "Willy."...
, the movie's captive star Keiko was returned to the coast of his native Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
. In 2002, the orphan Springer
Springer (orca)
Springer , officially named A73, is a wild killer whale from the Northern Resident Community of whales which every summer frequent the waters off the northern part of Vancouver Island, British Columbia...
was discovered in Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
, Washington. She became the first whale to be successfully reintegrated into a wild pod after human intervention, crystallizing decades of research into the vocal behavior and social structure of the region's killer whales. The saving of Springer raised hopes that another young killer whale named Luna
Luna (Orca)
Luna also known as L98 or Tsuux'iit, was a killer whale born in Puget Sound. After being separated from his mother as a toddler, Luna spent five years in Nootka Sound, off the west coast of Vancouver Island.Although Luna was healthy and his presence in the area delighted tourists and drew a large...
who had become separated from his pod could be returned to it. However, his case was marked by controversy about whether and how to intervene, and in 2006 Luna was killed by a boat propeller.
Whaling
The first records of commercial hunting of killer whales date to the 18th century in Japan. During the 19th and early 20th centuries, the global whalingWhaling
Whaling is the hunting of whales mainly for meat and oil. Its earliest forms date to at least 3000 BC. Various coastal communities have long histories of sustenance whaling and harvesting beached whales...
industry caught immense numbers of baleen
Baleen whale
The Baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea . Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans,...
and sperm whales, but largely ignored killer whales because of their limited amounts of recoverable oil, their smaller populations, and the difficulty of taking them. Once the stocks of larger species were depleted, killer whales were targeted by commercial whalers in the mid-20th century. Between 1954 and 1997, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
took 1,178 killer whales and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
took 987. Over 3,000 killer whales were taken by Soviet whalers, including an Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
catch of 916 in 1979-80 alone, prompting the International Whaling Commission
International Whaling Commission
The International Whaling Commission is an international body set up by the terms of the International Convention for the Regulation of Whaling , which was signed in Washington, D.C...
to recommend a ban on commercial hunting of the species pending further research. Today, no country carries out a substantial hunt, although Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
permit small subsistence hunts.
Killer whales have helped humans hunting other whales. One well-known example was in Eden, Australia
Killer whales of Eden, Australia
The killer whales of Eden, Australia were a group of killer whales known for their co-operation with human hunters of other whale species. They were seen near the port of Eden in southeastern Australia between 1840 and 1930. A pod of killer whales, which included amongst its members a distinctive...
, including the male known as Old Tom. Whalers more often considered them a nuisance, however, as they would gather to scavenge meat from the whalers' catch. Some populations, such as in Alaska's Prince William Sound
Prince William Sound
Prince William Sound is a sound off the Gulf of Alaska on the south coast of the U.S. state of Alaska. It is located on the east side of the Kenai Peninsula. Its largest port is Valdez, at the southern terminus of the Trans-Alaska Pipeline System...
, may have been reduced significantly by whalers shooting them in retaliation.
Captivity
Organizations such as the World Society for the Protection of Animals
World Society for the Protection of Animals
The World Society for the Protection of Animals is an international non-profit animal welfare organization and also a federation of such organisations and active in over 150 countries with more than 1000 member societies.- Organization :...
and the Whale and Dolphin Conservation Society
Whale and Dolphin Conservation Society
the Whale and Dolphin Conservation Society is a wildlife charity that is dedicated solely to the worldwide conservation and welfare of all whales, dolphins and porpoises...
campaign against the practice of keeping them in captivity. In captivity they often develop pathologies, such as the dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
collapse seen in 60–90% of captive males. Captives have vastly reduced life expectancies, on average only living into their 20s. In the wild, females who survive infancy live 50 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 30 years on average, and up to 50–60 years. Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild. Critics claim that captive life is stressful due to these factors and the requirement to perform circus tricks that are not part of wild killer whale behavior. Wild killer whales travel up to 160 kilometres (99.4 mi) each day, and critics say that the animals are too big and intelligent to be suitable for captivity.
Captives occasionally act aggressively towards themselves, their tankmates, or humans, which critics say is a result of stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
. Tilikum
Tilikum (orca)
Tilikum , sometimes misspelled Tillikum, is a bull orca who lives in captivity at SeaWorld Orlando. He has sired many offspring, and has been involved in the deaths of three people. Following a year long hiatus after his last incident, Tilikum returned to performing at SeaWorld Orlando on 30 March...
, a captive killer whale born in the wild, has been involved in three fatalities including one in which he grabbed a trainer and pulled her underwater, eventually drowning her. Experts are divided as to whether the injuries and deaths caused by captive killer whales have been accidents or deliberate attempts to cause harm.
Further reading
- Hoyt, Erich. 1998. Orca: The Whale Called Killer, Camden House Publishing, ISBN 978-0-920656-25-9
External links
- Orca-Live – Orcas in Johnstone Strait, British Columbia
- Salish Sea Hydrophone Network - Listen live to orcas in Washington State, U.S.
- Video:Orca Attack Seal with Waves (YouTube)
- Video of Type C Killer whales in the Antarctic
- Keep Whales Wild
- Marine Wildlife Guidelines for Boaters, Paddlers and Viewers
- Killer whale devours great white shark