From the webpages of NPCA.

http://www.npca.org/marine_and_coastal/marine_wildlife/orca.html

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Orcas  

Orcas (also called "killer whales") are one of the most recognizable cetacean species because of their distinctive black and white markings. They're also known for their large dorsal fin, which can reach more than five feet in an adult male and about three feet in females. Variations in dorsal fin size and shape, and in so-called saddle marks the gray patch behind the dorsal fin, are used by those studying orcas to tell them apart.

Full Article: http://www.hsus.org/marine_mammals/a_closer_look_at_marine_mammals/orcas.html

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Distribution:

Orcas are among the most widely-distributed mammals on Earth. In many areas they are not particularly common, but they are found in all the oceans of the world. Some of the best places to see them are: Vancouver Island, Canada; the San Juan Islands, USA; and Tysfjord, in northern Norway. They tend to be more common in cold waters (such as the Arctic and Antarctic) than in warm waters and generally prefer deep water, although they are quite often seen in shallow bays and estuaries.

Population Size:

Although the number of whales in particular populations may be known, the world-wide population size of orcas is not.

Threats:

Boat traffic, Hunting/Whaling, Habitat loss, Noise pollution, Prey depletion (lack of food), Captivity industry

WDCS is the global voice for the protection of whales, dolphins and their environment

Ref: http://www.wdcs.org/dan/publishing.nsf/allweb/15AA5167CB9C98C9802569D000417CBC

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Now that's quite a bit of information.  It's going to take me some time to read it all.  I recognize the illustrations for information I have on Orca's. Sea World and Busch Gardens do have quite a bit of information on both Orca's and dolphins.  I've sent students to those sites before for information.  I always knew they were good sites.  How about Montery Bay Aquarium?  I haven't checked on their information.

   I love the jumping Orca.  I borrowed it.  Hope you don't mind.  I even had it jumping in the middle of the typing.  It was really funny, very hard to read, but funny.

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Orcas are one of the fastest animals in the sea. The record holder is a male timed at 55.5 km/h (34.5 mph). They are also one of the most widespread mammals on Earth.

Full Link: http://www.bbc.co.uk/nature/wildfacts/factfiles/91.shtml

From a different source.

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Just wanted to note that I am not a fan of Seaworld but part of their website (copied above) happens to be an excellent source of information.

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SeaWorld/Busch Gardens Animal Information Database
www.seaworld.org / www.buschgardens.org

©2002 Busch Entertainment Corporation.
All Rights Reserved.

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5.  The question of animal intelligence is intriguing.  It is extremely difficult, and in many cases misleading, to rate the intelligence of different kinds of animals.  In fact, we have yet to provide a reliable and consistent intelligence test for humans.  It would be inaccurate to quantify or qualify the intelligence of marine mammals, for there is no way known to test and measure such a thing.

a.  The brain of one large male killer whale weighed 7.2 kg (15.8 lb.), a weight significantly larger than the 2.2 kg (5 lb.) brain of a human.  But again, it would be a mistake to judge an animal's intelligence on the size of its brain.

b.  What we do know is that dolphins and whales are capable of performing some very complex tasks.  Genetically, marine mammals are predisposed to responding more efficiently to stimuli found in aquatic environments.  They learn different tasks at different rates and there is great variation among individual animals of the same species.

c.  Researchers continue to gather information on short- and long-term memory in whales and dolphins, but much about an animal's ability to learn continues to be a mystery.

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A.  The International Whaling Commission.

1.  In 1946, 14 countries formed the International Whaling Commission (IWC) by signing the International Whaling Convention.  The IWC set regulations of whaling to protect the future of whale stocks as a resource to humans.

2.  Currently the IWC has no jurisdiction over dolphins such as killer whales.   However, now that the harvest of most large whales has stopped, the IWC has expressed an interest in playing a role in managing smaller cetaceans as well.

B.  Legal protection.

1.  The Marine Mammal Protection Act (MMPA) of 1972 made it illegal to hunt or harass any marine mammal in United States waters.

a.  In accordance with the MMPA, the National Marine Fisheries Service (NMFS) has jurisdiction over all whales in the waters of the United States.

b.  The primary objective of the MMPA is to maintain the health and stability of the marine ecosystem and to obtain and maintain optimum sustainable populations of marine mammals.

c.  The MMPA does allow exceptions for native subsistence hunting; collecting or temporarily restraining marine mammals for research, education, and public display; and taking a restricted number of marine mammals incidentally in the course of fishing operations.

2.  The Convention on International Trade of Endangered Species of Wild Fauna and Flora (CITES) is an international treaty developed in 1973 to regulate trade in certain wildlife species.  CITESprotects all species of whales.

C.  Field research.

1.  Much about the lives of killer whales still remains a mystery.  However, scientists and researchers are studying many aspects of killer whales around the world.

2.  In the future, analyzing biochemical and chromosomal characteristics may help define genetic relationships among pods and regional populations of killer whales.   Call patterns, body shape, and coloration are currently used in identifying separate killer whale populations.

3.  Researchers work to increase their photo-identification catalogs for killer whales.  This has become an important research tool for studying various aspects of cetacean biology including movements, reproduction, behavior, and population dynamics.

D.  The importance of marine life parks.

1.  Most people do not have the opportunity to observe animals in the wild.   In a 1995 Roper Poll, 87% of those interviewed agreed that visiting zoological facilities was their only opportunity to see wild animals such as killer whales.  The unique opportunity to observe and learn directly from live animals increases public awareness and appreciation of wildlife.  In the same Roper Poll, 92% of those questioned agreed that zoological parks are a vital educational resource.

2.  In the past several decades, marine life parks have learned a great deal about killer whales from ongoing research programs.  The advantages of studying killer whales in controlled areas include the possibility of continuous observations without being impeded by weather, darkness, or location.

3.  In the protected environment of a marine zoological park, scientists can examine aspects of killer whale biology that are difficult or impossible to study in the wild.

a.  SeaWorld trainers and veterinarians perform regular physical exams on the killer whales to monitor and maintain their health.  Every two to four weeks trainers take body measurements on each whale, including body length; girth at several points; and dimensions of the flippers, flukes, and dorsal fin.

b.  Killer whales are further trained to present their tail flukes for blood samples and to urinate on signal.

c.  Medical technologists perform clinical evaluations of hematology, serum chemistry, urinalysis, and blowhole cultures.

d.  Pregnancy is diagnosed through serum progesterone analysis, urine progesterone metabolite analysis, ultrasound, and daily observations of social interactions.

4.  Toothed whales only grow one set of teeth in their lives so SeaWorld places great importance on the care of killer whale teeth.

a.  Wild killer whales often have a variety of dental problems.  It is not uncommon, for example, to see killer whales in their natural environment with teeth that are disease-ridden, worn, or broken.  This is probably due to their aggressive feeding habits or old age.  Wild killer whales have been observed with their teeth worn down to the gum level, which often exposes the pulp.  Abscesses can occur, resulting in lower jaw misalignment in some cases studied.

b.  Up to several times a day, a killer whale at SeaWorld can have its teeth cleaned and flushed with a water pic.  X-rays are used to examine the teeth more thoroughly as well.

c.  If more serious conditions arise, veterinarians that specialize in animal teeth work with the trainers to treat dental problems with killer whales at the SeaWorld Adventure Parks.

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d.  To date, the only effective strategies for reducing killer whale interactions with fishing boats were temporarily stopping fishing operations, moving the fishing fleet to distances greater than 111 km (60 nautical mi.) away, and changing the target species from black cod to Pacific cod.

8.  High concentrations of chemical such as PCBs and DDT have been found in North Pacific killer whales.  These industrial pollutants have been introduced to the marine environment through mining operations, offshore oil development, agriculture, pulp mills, and other coastal industrial developments.  The pollutants enter the food chain through dinoflagellates and zooplankton, which are eaten by larger animals.   These animals are eventually eaten by larger fishes and other predators.  The pollutants become concentrated and reach high levels in the bodies of larger predators, such as killer whales.

9.  In one study, tissue samples from killer whales stranded in Washington, Alaska, and British Columbia showed three whales with DDT concentrations above 400 parts per million and PCBs exceeding 100 parts per million in other killer whales.  How these pollutants affect killer whales is not fully understood and research continues in this field.

F.  Whale watching.

1.  Where once whaling boats pursued killer whales to hunt them, a new group of thrill-seeking humans venture forth to see these amazing creatures just to enjoy their beauty.

2.  Tours specifically designed to view killer whales are concentrated in the area of British Columbia and Puget Sound off the west coast of North America.  Western Johnstone Straits and Blackfish Sound off the southern end of Vancouver Island are places where encountering killer whales is likely, depending on the time of the year.

3.  For the adventurous, there are boat tours that take guests to the frigid waters of Antarctica, where killer whales are plentiful.

4.  These whale watching tours are a huge, growing business.  The economic impact of these tours is estimated to be well over $4 million U. S. dollars for the Vancouver Island area alone.

5.  The steady growth of recreational whale watching has raised some concerns with killer whale researchers.  For example, it has been recently noticed that many killer whales avoid the shallow beaches where they rub their skin if any boats, even non-motorized ones, are in the general area.  Also, whale watchers along the beaches seem to force the killer whales to leave.

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E.  Human impact.

1.  Humans have long been fascinated by killer whales, but until recently very little was known about their lives at sea.

a.  The image of a killer whale was found on cave drawings in northern Norway, and it is estimated to be some 9,000 years old.

b.  A few cultures respected killer whales, yet much of the ancient world did not.   During the first century AD, a Roman scholar named Pliny the Elder wrote that killer whales "cannot be properly depicted or described except as an enormous mass of flesh armed with savage teeth."

c.  In 1835, R. Hamilton wrote that the killer whale "...has the character of being exceedingly voracious and warlike.  It devours an immense number of fishes of all sizes... when pressed by hunger, it is said to throw itself on every thing it meets with..."

d.  Many in modern civilization still envisioned killer whales as terrifying threats to humans, with a 1973 United States Navy diving manual warning that killer whales "will attack human beings at every opportunity."

e.  Killer whales are animals shrouded in myth, and many times this misinformation has led to the destruction of these whales.

2.  In certain areas of the world, killer whales and fishermen compete for the same food sources.

a.  This is especially true in the Bering Sea, where killer whales and Alaskan and Japanese fishermen regularly clash over black cod (Anoplopoma fimbria).

b.  A similar conflict occurs between Brazilian fishermen in the Atlantic who target tunas (Thunnus spp.) and swordfish (Xiphias gladius).

3.  In the past, confrontations between humans and killer whales led angry fishermen to demand the destruction of these cetaceans.  Governments, such as the United States, were inclined to side with the fishing communities.  One such example of this historic, bitter conflict can be found in the following 1956 article prepared by the United States Navy:

4.  Killer whales have been exploited as a natural resource or have been taken incidentally during other whaling operations.

a.  In 1958, the government of Japan sanctioned the use of 50-caliber guns to be used against killer whales.  An average of 60 killer whales were caught annually off the waters of Japan, with the meat being sold in local markets and the viscera (internal organs) used as fertilizer or bait.

b.  The most valuable commodity from these killer whales was oil derived from boiling the blubber.

c.  Sometimes their thick hides were made into soles of shoes.

5.  From 1954 to 1977, for example, Norwegian and Japanese whalers took a combined 2,963 killer whales.  Russian whalers took 1,945 between 1948 and 1980.  Today, the whaling industry does not target killer whales, although killer whales are legally subsistence-hunted by certain indigenous arctic peoples.

6.  Some fishermen blame the destruction of millions of dollars of equipment and fish loss on killer whales, and on rare occasions some have taken to shooting killer whales.

7.  Others are attempting to find alternatives to destroying killer whales.

a.  Alaskan fishermen have attempted a variety of methods in order to deter killer whale depredation on long-line catches of codfish including the use of decoy boats, combining hauling operations, fishing at night, acoustic harassment devices, and the use of electric currents.

b.  Other more aggressive attempts to discourage them included using high-powered explosive devices and even illegally shooting the whales.  None of these methods have proven effective.

c.  Other methods being examined to eliminate long-line depredation include the use of sparker devices (which emits a flash of light to startle the whales), rubber bullets, bubble screens (to interfere with the acoustical senses of the whales), using chemicals such as lithium chloride and ether (to promote sickness/vomiting), reducing sound levels generated by backhauling equipment to avoid attracting killer whales to fishing operations, and playing recordings of previous long-line operations to confuse the whales.

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Longevity and Causes of Death

A.  Longevity/Aging Studies

1.  No one knows for sure how long killer whales live.

2.  For unknown reasons, killer whales have a high calf mortality rate in some areas of the world.  In the Pacific Northwest, for example, 43% of all calves die in the first six months.  In other killer whale populations, calf mortality may be as high as 50% during the first year.

3.  Long-term studies will ultimately answer this question.  By counting growth layers in teeth, scientists find that killer whales in the North Atlantic may live at least 35 years.  Studies are still refining this method of aging.

Researchers can estimate a killer whale's age by examining a sliced section of tooth and counting growth layer groups.

4.  Scientists in the Pacific Northwest estimate life expectancies by using information derived from field observations that began in the 1970s.  These scientists believe that if a killer whale survives the first six months, a female's life expectancy is 50 years and a male's is 30 years.

5.  With continued research, it is likely that differences in longevity will be found in killer whale populations around the world.

B.  Disease and parasites.

Killer whales succumb to numerous natural diseases and parasites.  Killer whale parasites include tapeworms, roundworms, and flukes.  Whales in general may suffer from viral, bacterial, and fungal infections.  In addition, they may develop stomach ulcers, skin diseases, and tumors.  Hodgkin's disease has been seen in killer whales and severe atherosclerosis of the coronary arteries was found in a stranded specimen.

Killer whales are top predators in the sea.  Healthy adults have no natural predators, but sharks prey on older, younger, or ill killer whales.

D.  Human interaction.

Coastal killer whales are more likely to be affected by pollution, competition with humans for limited stocks of fish, and other environmental factors.

E.  Stranding.

1.  On rare occasions, killer whales strand along the shoreline.  Why this happens is largely unknown.

a.  One theory behind this is that killer whales accidentally strand when they chase prey into shallow waters.

b.  During one mass stranding of 14 killer whales in northern Norway, it is thought that the whales became stranded while chasing herring.  All 14 were successfully pulled back into the water and swam off to rejoin their herd a short time later.

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a.  When nursing, the calf suckles from nipples concealed in abdominal mammary slits.

b.  Killer whale calves observed at SeaWorld began nursing several hours after birth.  First successful nursing attempts ranged from 2.6 to 28 hours after birth.

c.  Calves nurse below water, close to the surface.  The mother glides in a horizontal position with her tail arched, and the calf swims on its side with its mouth on the right or left mammary gland.

To nurse, a calf swims on its side and suckles from nipples concealed in abdominal mammary slits.

d.  Calves nurse about 5 to 10 seconds at a time, several times an hour, 24 hours a day.  Nursing frequency peaks the first day or two following birth, at about 90 minutes total nursing.  Thereafter, frequency decreases dramatically to 10 minutes per day or less, as the calf becomes more adept at nursing and obtains more milk at each feeding.

e.  The mother's milk is very rich so that the calf rapidly develops a thick, insulating layer of blubber.  The milk fat content fluctuates as the calf develops, ranging from about 48% milk fat at the beginning of the nursing period and gradually decreasing to approximately 28% in the months that follow.

f.  A calf may nurse for 12 months or more.  A calf may essentially be weaned at one year of age but may continue to nurse occasionally for several more months.

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A. Births at Zoological Facilities.

1.  On September 26, 1985 at SeaWorld Orlando, a killer whale gave birth to a female calf, the very first killer whale successfully born and raised in a zoological environment.

2.  Baby Shamu thrived in her environment and eventually reached adulthood herself.  On February 2, 1993, at SeaWorld San Antonio, she gave birth to the first second-generation killer whale calf.  The calf's mother -- the very first killer whale born at SeaWorld -- had her second calf on June 17, 1995 and her third on June 22, 1999.

3.  SeaWorld has the largest killer whale breeding program of any park.  To date, 13 calves have been successfully born at SeaWorld Orlando, San Diego, and San Antonio.

4.  Other successful zoological park births have occurred at Sealand of the Pacific (British Columbia), Marineland of Canada (Niagara Falls), Kamogawa Sea World (Japan), and Marineland of Antibes (France).

 
Killer whale calves are born either tail-first or head-first.

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Reproduction  

A.  Sexual maturity

1.  Field studies on many aspects of killer whale reproduction are not available, yet much has been learned at marine life parks.  Studies of killer whales in marine zoological facilities suggest that females become sexually mature when they reach 4.6 to 4.9 m (15-16 ft.), at about 6 to 10 years.

2.  Males usually become sexually mature when they reach about 5.5 to 6.1 m (18-20 ft.), at about 10 to 13 years.  In the SeaWorld Adventure Park system, one male successfully mated at approximately 7.5 to 8 years of age.  In the wild, social factors greatly influence a male's breeding success.  Males may not successfully reproduce until they are much older, larger, and more able to compete with other males.

B.  Mating activity.

1.  Killer whales are considered polygamous as they tend to mate with any number of partners.

2.  Females come into estrus or 'heat' several times during the year.   Observations of females in zoological parks indicate that killer whales undergo periods of multiple estrus cycling (polyestrus), interspersed with periods of non-cycling.   This period is highly variable, as is the period of non-cycling, both for one whale over time, and between whales.

3.  Breeding may occur in any season, but it is most common in the summer.  In the North Atlantic, mating seems to peak in October and November; in the western North Pacific, mating seems to be at its highest between May and June.

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6.  A pod of 30 to 40 killer whales was seen following a fleet of trawler ships in the northeastern area of the Shetland Islands in the United Kingdom.  As the trawlers brought aboard quantities of netted mackerel (Scomber scombrus), the killer whales consumed fishes that slipped from the nets or dead fishes tossed off the ships.

7.  Research has shown that resident whales have a wider sound repertoire than transient whales, which may be partially related to their hunting habits.

a.  Transients vocalize far less frequently than residents.  While resident whales have been observed vocalizing during all forms of behaviors, transients only vocalize during play and after a kill.

b.  One theory for this is that resident pods hunting schools of fish may need to rely on a great deal of communication to coordinate their assault.  Transients may need to use stealth to approach marine mammals that might be alerted if the killer whales were to vocalize.

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Diet and Eating Habits

A.  Food preferences and resources.

1.  Active and opportunistic, killer whales are without a doubt top predators in the ocean.  In fact, they are the largest predator of warm-blooded animals ever known.

2.  Fishes, squids, seals, sea lions, walruses, birds, sea turtles, otters, penguins, cetaceans (both mysticete and odontocete), polar bears, reptiles, and even a moose -- they have all been found in the stomach contents of killer whales.

3.  Perhaps the most interesting thing found in the stomachs of killer whales is the remains of other killer whales.  How this came to be is uncertain as killer whale predation on other killer whales is rare.  Perhaps they scavenged the remains of dead killer whales, as killer whales are known to eat the remains of other animals.

4.  The diets of killer whales vary from one region to another.

a.  In the Antarctic, killer whales eat about 67% fishes, 27% marine mammals, and 6% squids.

b.  In the Bering Sea near Alaska, they eat about 65% fishes, 20% squids, and 15% marine mammals.

c.  The diets of resident and transient killer whales differ as well.   Resident pods eat a wide variety of fishes and rarely seek out marine mammals.   Transient groups primarily eat marine mammals and occasionally eat fishes.

Adult killer whales eat approximately 3% to 4% of their body weight in food per day; fully weaned calves can eat up to approximately 10% of their body weight during growth periods.

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F.  Sleep.

3.  While resting, killer whales may swim slowly or make a series of 3 to 7 short dives of less than a minute before making a long dive for up to three minutes.

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4.  SeaWorld observers found that calves receive social 'discipline', from their mothers and other significant adults, as early as two days (with an average of 56 days) after birth.  'Discipline' may be in the form of restraining (corralling the calf thus restricting its movements) or tooth-scratching.

4.  Behavior studies of several cetacean species in zoological parks suggest that killer whales are among the most curious of all whales, with a great tendency to 'play' and to manipulate objects.

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Behavior

A.  Social structure.

1.  Killer whales live in cohesive long-term social units called pods.

2.  The size of a pod usually varies from fewer than 5 to about 30 individuals.   Pod sizes may change with different geographic locations; off Alaska and Antarctica, groups of more than 100 animals have been seen.

3.  Pods usually consist of males, females, and calves of varying ages.   Females and juveniles generally remain in the center of the pod, while adult males swim at the wings.

4.  A pod is not the smallest or largest social group in a killer whale community.   Researchers have identified the most fundamental social units in a resident pod as maternal groups.  A maternal group consists of a mother and her offspring (not including adult daughters with offspring of their own).  One or more maternal groups may travel together in a subpod.  Whales in a subpod are likely to be closely related; a subpod contains mothers and daughters, and probably sisters and cousins.

5.  A clan is a social level above the pod level.  Clans are made up of pods in an area with similar dialects and are thought to be related.  These pods may have developed from one ancestral pod that grew and fragmented over time.  Finally, the top level of the killer whale social structure is a community.  A community is composed of several pods that have been seen to travel together.  Pods from one community have not been observed traveling with those of another, even if their ranges overlap.

6.  Sometimes smaller pods may join to form groups of 50 or more individuals (up to 500 in some cases) which are sometimes referred to as herds or aggregations

7.  There is an occasional exchange of members between pods, especially during breeding season.

6.  There is evidence for the existence of at least eight communities of Alaskan killer whales: four resident stocks, three transient stocks, and one offshore stock.

7.  Bioacoustic studies can be an important means of tracking pod movements.  If they provide a reliable index of genetic variability, they can also become a useful management tool.

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D. Thermoregulation.

A countercurrent heat exchange system in the flippers, flukes, and dorsal fin helps killer whales maintain body temperature.

1. Heat loss in water is about 27 times faster than in air at the same temperature.

2. Despite this rapid heat loss, killer whales are able to maintain a high body temperature that ranges from 36.4 C (97.5°F) to 38 C (100.4°F).

3. Killer whales have several adaptations to help them stay warm even in frigid water:

a. A killer whale has a thick layer of body fat, called blubber, that lies underneath its skin.  This blubber layer, from 7.6 to 10 cm (3 - 4 in.) thick, insulates the whale and streamlines its body.

b. The killer whale's fusiform body shape and reduced limb size, in comparison to land mammals, decreases the amount of surface area exposed to the external environment.   Blubber also functions as an energy reserve.

c. In general, cetaceans have a higher metabolic rate than land mammals of similar size.  This increased metabolism generates a great deal of body heat.

d. Mammals lose body heat when they exhale.  Because they breathe less frequently than land mammals, killer whales conserve a considerable amount of heat.

4. A killer whale's circulatory system adjusts to conserve or dissipate body heat and maintain body temperature.

a. Arteries in the flippers, flukes, and dorsal fin are surrounded by veins.   Thus, some heat from the blood traveling through the arteries is transferred to the venous blood rather than the environment.

b. This countercurrent heat exchange helps whales to conserve body heat.  When a whale dives, blood is shunted away from the body surface.  This decrease in circulation conserves body heat as well.

5. During prolonged exercise or in warm water, a killer whale may need to dissipate body heat.  In this case, circulation increases to arteries near the surface of the flippers, flukes, and dorsal fin, and deceases to arteries providing blood to the body core.  Excess heat is shed to the external environment.

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A. Swimming.

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6.  In studies at SeaWorld, killer whales visually discriminated among similar objects.  During more than one hundred trials a killer whale was shown an object and cued to find a matching object.  When given two choices, the whale chose the matching object with 92% accuracy, and when three choices were presented the whale's accuracy was about 82%.  Researchers did not determine whether the whale was responding to shape, size, or color.  Future studies may provide more detailed information on the visual abilities of killer whale.

7.  In the often darkened waters of the ocean, eyesight may be of little help in locating prey.  Under these conditions, killer whales probably rely on sound production and reception to navigate and find prey in murky waters.

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Senses

A.  Hearing.

1.  Killer whales have an acute sense of hearing, and the auditory cortex of the brain is well developed.

B.  Hearing range.

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8.  Because of the huge diversity of killer whale dorsal fins and the adjacent saddle patch, researchers take pictures of these fins to identify individuals and their pods, much like fingerprints are taken to identify humans.

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Physical Characteristics

A.  Size.

1.  Although small compared to some whales, killer whales are the largest predators of mammals ever known.  Male killer whales, or bulls, average 5.8 to 6.7 m (19-22 ft.) and usually weigh between 3,628 and 5,442 kg (8,000-12,000 lb.).

2.  Females, or cows, average 4.9 to 5.8 m (16-19 ft.) and usually weigh between 1,361 and 3,628 kg (3,000-8,000 lb.).

3.  Individual sizes vary significantly between geographical areas.  Length estimates for more than 2,000 killer whales taken by North Atlantic whaling operations show male North Atlantic killer whales average about 6.1 m (20 ft.) while females average about 5.5 m (18 ft.).

4.  The largest male ever recorded was 9.8 m (32 ft.) and weighed 10,000 kg (22,000 lb.).  The largest female recorded was 8.5 m (28 ft.) and weighed 7,500 kg (16,500 lb.).

B.  Body shape.

A killer whale has a sleek, streamlined, fusiform (tapered at both ends) body shape.

female

male

A killer whale has a sleek, streamlined, fusiform body. Its physical characteristics are adapted for life in an aquatic environment.

6.  Albinism in killer whales has been reported 74 times in a 36-year period, and as recently as 1970 an all-white killer whale calf was studied in British Columbia.

4.  One particularly large male had pectoral fins that measured 203 cm (80 in.) long and 109 cm (43 in.) wide.

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Distribution and Habitat

A.  Distribution/Habitat.

1.  Next to humans, killer whales are the most widely distributed mammal.   Killer whales inhabit all oceans of the world but are most numerous in the Arctic, the Antarctic, and areas of cold water upwelling.  They can be sporadically sighted along the shores of Washington, Oregon, California, and Baja California and along the eastern coast of the United States.

2.  In addition to cold water areas, killer whales also have been seen in warm water areas such as Hawaii, Australia, the Galapagos Islands, the Bahamas, and the Gulf of Mexico.  Such sightings are infrequent, but they do demonstrate the killer whales' ability to venture into tropical waters.  Even more surprising, killer whales have been seen in fresh water rivers around the world such as the Rhine, the Thames, and the Elbe.  One even traveled some 177 km (110 mi.) up the Columbia River to eat fish.

3.  Although killer whales can be found in both the open ocean and coastal waters, they primarily inhabit the continental shelf in waters less than 200 m (656 ft.) deep.   In cold water areas, their distribution is limited by seasonal pack ice.

In some areas, the seasonal movements of killer whales are influenced by the migration of fish and other prey.  In eastern Canada, killer whale movements are often a response to seal and rorqual whale migrations, while northeastern Atlantic killer whales seem to follow herring.  In the Bering, Chukchi, and Beaufort seas, killer whales make considerable seasonal movements in response to the advance and retreat of the pack ice.

1.  Because of their wide distribution, the worldwide population of killer whales is unknown. Few regional groups of killer whales have been studied thoroughly, making worldwide population estimates difficult.  Some specific killer whale populations have been examined, however:

a.  The southeastern Alaska population is estimated at 250.

b.  The populations around Prince William Sound, western Alaska/Bering Sea, and British Columbia/Puget Sound by Vancouver Island are believed to be around 300 for each area.

c.  Population estimates in the Antarctic range from 70,000 to 180,000.

2.  Killer whales are not regarded as an endangered species.

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Scientific Classification

A.  Order--Cetacea.

All dolphins, porpoises, and whales are grouped together in the scientific order Cecacea.  This large order of approximately 80 living species is divided into three suborders:  the toothed whales or Odontoceti (killer whales, dolphins, porpoises, beluga whales, narwhals, beaked whales, and sperm whales), the baleen whales or Mysticeti (blue whales, humpback whales, gray whales, and right whales), and the Archaeoceti (a group of fossil whales, now extinct).

B.  Family--Delphinidae.

Dolphins and their immediate kin are included in the scientific family Delphinidae. This family is represented by about 32 species, including some that have similar sounding names to killer whales such as pygmy killer whales (Feresa attenuata) and false killer whales (Pseudorca crassiddens).  Killer whales are the largest member of the dolphin family.

C.  Genus, species -- Orcinus orca

1.  Because of their fierce reputation, killer whales are sometimes called ballena asesina ("assassin whale") by the Spanish.  They were referred to as "whale killers" by sailors who witnessed their attacks on larger cetaceans, an over time this name was changed to "killer whales".  They are called this not because they harm humans but because they kill other whales.

2.  Some researcher believe distinct species of killer whales exist, especially in the Antarctic.  The majority of scientists, however, group killer whales as a whole and label them all as Orcinus orca.  Orcinus is probably derived from Orcus, an ancient mythological Roman god of the netherworld -- a reference to the ferocious reputation of this animal.  Orca literally means "the shape of a barrel or cask" in Latin, likely due to the killer whale's body shape.

D. Fossil Record.

1.  The classification of whales puzzled early researchers even though cetaceans roamed the ocean long before recorded history.  Modern forms of both odontocetes and mysticetes appear in the fossil record an estimated five to seven million years ago. Some believe the early whales arose 55 to 65 million years ago from (now extinct) ancient land mammals that ventured back into the sea.  One such extinct creature may have been Ambulocetes natans.  Ambulocetes natans was discovered in Pakistan and fossil remains show a legged land animal that also feature several characteristics of whales.

Odontoceti
killer whale, Orcinus orca

Mysticeti
gray whale, Eschrichtius robustus

Archaeoceti

The scientific order Cetacea is further divided into three suborders: the Odontoceti, the Mysticeti, and the Archaeoceti.

2.  Numerous large fossilized teeth, primarily from the Pliocene (two to five million years ago), are thought to be those of O. orca or a closely related species.  One such species, O. citoniensis, is an extinct whale that had a higher tooth count and smaller size compared to modern killer whales.

3.  Because whales spend their entire lives in water, they were wrongly classified as a type of fish in ancient days.  Finally the Greek philosopher Aristotle (384-322 BC) correctly classified whales as mammals in his book Historia Animalium.  A killer whale has more in common with a human than with a fish as both a whale and person share similar mammalian characteristics.  For a example, a fish is unable to control its body temperature.  A mammal, such as a whale, maintains a constant body temperature independent of its environment.  Killer whales have a high body temperature similar to that of humans.

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