Orcinus orca

Orcinus orca

(killer whale)

Orcinus orca

Orca (Killer Whale)

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Delphinidae

Genus: Orcinus

species: Orcinus orca



The killer whale is actually not a whale. It is the largest member of the dolphin family. Killer whales have a very distinctive black and white coloration. They are black on their upper surface with a while spot behind each eye. They are white on their lower surface. Male killer whales have straight, tall (up to 6 foot) dorsal fins while females have shorter (3 foot) sickle shaped dorsal fins. Killer whales have 46 to 50 cone-shaped teeth that interlock and are used to tear and grasp. The killer whale shares characteristics with whales, such as breaching, but it also reacts like the smaller members of the dolphin family. For instance, it is capable of spyhopping (a vertical position using its tail to keep it upright) to get a better view of its surroundings.

Geographic Range

Most common in Arctic and Antarctic waters, but also occurs in all other oceans.

 

Habitat

Killer whales are found in all oceans, but mostly in cooler waters. In the Antarctic they live amid pack-ice, but they are said not to extend beyond the ice-line in the Arctic ocean. They are oceanic for the most part, but will approach the shore when attracted by food resources.

Reproduction

Orcas are polygynous; each group, or pod, contains one breeding male and several breeding females.

Although the whales may breed near the end of the year in some areas, Killer whales appear to breed in spring and summer off the coast of the state of Washington. The gestation period is around a year, and the young at birth are about two meters long.

Behavior

Orcas are highly social whales, travelling about in discrete social units called pods. The relationships within the pod are stable and may persist from one generation to the next. Each pod contains one adult male, several adult breeding females and a number of sub-adults of both sexes. Pod size may vary from as few as four to as many as forty. Small pods, which are split off from larger ones, are less stable and may die out within a generation, probably because the larger pods monopolize preferred food resources. The orcas hunt together, and this behavior accounts for the evolution of the social links that result in pod formation.

Food Habits

Killer whales are versatile predators. They feed on a wide variety of species, ranging from fish to warm-blooded prey such as birds, seals or even other whales. They require 2.5 to 5 percent of their body weight in food each day. making access to a substantial and reliable food source important. Fish and squid probably make up the bulk of their diet, with some pods (see Behavior and Social Systems) specializing in warm-blooded prey. Methods for feeding on squid are unknown, but when hunting in packs the whales trap and atack prey simultaneously.

Economic Importance for Humans: Negative

May interfere with commercial fishermen.

Economic Importance for Humans: Positive

Many fishermen use orcas to catch fish that the pods have driven together while hunting.

Conservation Status

Though orcas have no official status, a decline in populations has been recorded. Possible reasons for the apparent decline in numbers include exploitation by whalers, killing by angry fishermen (the whales eat their intended catch), declining food stocks (due to overfishing), pollution, and disease. Except for waters around Iceland and Antarctica, orca populations may be suffering. Some gentically isolated populations may even be endangered.

Other Comments

The worldwide distribution of Orcinus orca may be related to its omnivorous diet and remarkable temperature tolerance.

The orca (Orcinus orca) is the largest member of the oceanic dolphin family Delphinidae. They are traditionally referred to as blackfish, a group including pilot whales, pigmy and false killer whales and melon headed whales. It is the second-most widely distributed mammal on Earth (after humans) and is found in all the world's oceans, from the frigid arctic regions to warm, tropical seas. It is also a versatile, deadly predator, eating fish, turtles, birds, seals, sharks and even other juvenile and small cetaceans. This puts the orca at the pinnacle of the marine food chain. The orca also attacks whales, in particular gray whales.

The name "killer whale" reflects the animal's reputation as a magnificent and fearsome sea mammal that goes as far back as Pliny the Elder's description of the species. Today it is recognized that the orca is a dolphin rather than a whale and that it is not a danger to humans. Aside from a boy who was charged (but not grabbed) while swimming in a bay in Alaska, there have been no confirmed attacks on humans. There have, however, been isolated reports of captive orcas attacking their handlers at marine theme parks.

Naming

The name "orca" (plural "orcas") was originally given to these animals by the ancient Romans, possibly borrowed from the Greek word ὄρυξ which (among other things) referred to a species of whale.

The term "orc" (or its variant "ork") has historically been used to describe a large fish, whale or sea-monster. It is now considered an obsolete equivalent for "orca."

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

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

There are still many, especially in the research community, who prefer the original name, believing it to be an appropriate description of a species that does indeed kill many animals, including other cetaceans. These supporters of the original name point out that the naming heritage is not limited to Spanish sailors. Indeed the genus name "Orcinus" means "from Hell" (see Orcus) and although the name "orca" (in use since antiquity) is probably not etymologically related, the assonance might have given some people the idea that it means "whale that brings death," or "demon from hell."

It is noteworthy that the name of this species is similarly intimidating in many other languages. In Finnish it is called miekkavalas which means "sword whale". To the Haida people native to the islands of Haida Gwaii off the coast of British Columbia, the animal was known as skana or "killing demon". The Japanese call them shachi , whose kanji character combines the radicals for fish  and tiger.

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

Taxonomy and evolution

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

Three distinct populations

Modern research indicates that there are three distinct population types or classifications of orcas off the western coastline of North America. While each looks similar, they have distinct genetic differences, food preferences, and habits. These are the called the transient, resident and offshore types. (See also: whalesbc.com)

Transient

Transient orcas generally travel in small groups, usually up to 7 or 8 animals. These are referred to as groups rather than pods because they do not have as strong a social bond, and do not necessarily remain as a family unit, probably due to their diet. They are generally seen cruising along the shorelines hunting for prey. It is this group’s ruthless hunting and eating habit that gained orca the nick name "killer whales." Often, to avoid injury, they will disable their prey before killing and eating it. This may involve throwing it in the air, slapping it with their tails, ramming it, or breaching and landing on it. The whole process can be quite lengthy at times, seeming to be like torture for the prey, but is primarily for safety and training for the young killer whales. Female transients are characterized by pointed dorsal fin tips. The range for transient killer whales is unknown, but may be as much as 1500 miles or more.[1]

Resident

Resident orcas are the most commonly sighted of the populations, often observed in coastal waters. Female residents characteristically have a rounded dorsal fin tip that terminates in a sharp corner. While nomadic, their range is much smaller, and they are known to visit certain areas consistently. The resident orca’s diet consists primarily of fish, including salmon and herring and they frequent areas where their preferred fish are abundant. They are continually on the move, sometimes traveling as much as 100 miles in a day, but may be seen in a general area for a month or more. Range for resident killer whale pods may be as much as 800 miles or as little as 200 miles. Resident orcas live in complex and cohesive family groups known as pods. Resident pods are generally larger than the transient and offshore pods, having up to 50 or more members. Several pods occasionally join to form what are referred to as superpods, sometimes numbering in excess of 150 animals. On November 15, 2005 the United States government listed the Southern Resident population of killer whales as an endangered species under the Endangered Species Act (ESA) due to deterioration of the three pods which spend most of the year in Georgia and Haro Straits, as well as Puget Sound in British Columbia and Washington state.

Offshore

Offshore orcas were given this name for what the name implies. They remain offshore cruising the open oceans feeding primarily on fish. They have been seen traveling in groups of up to 60 animals. Currently there is little known about the habits of this population, but they can be distinguished genetically from the residents and transients. Female offshores are characterized by dorsal fin tips that are continuously rounded. [2]

Physical characteristics

The animals are distinctively marked, with a black back, white chest and sides and a white patch above and behind the eye. They have a heavy and stocky body and a large dorsal fin with a dark gray "saddle patch" behind it. Males can be up to 9.5 m long (31 ft) and weigh in excess of 6 tons; females are smaller, reaching up to 8.5 m (28 ft) and a weight of about 5 tons. Calves at birth weigh about 180 kg and are about 2.4 m long (8 ft). Unlike most dolphins, the pectoral fin of an orca is large and rounded — more of a paddle than other dolphin species. Pectoral fins of males are significantly larger than those of females. At about 1.8 m (6 ft), the dorsal fin of the male is more than twice the size of the female's, and is more of a triangle shape — a tall, elongated isosceles triangle, whereas the dorsal fin of the female is shorter and generally more curved. Nicks, cuts and scrapes on these fins, as well as distinctive features of each fin, help scientists identify individuals. There are also minor variations in physical characteristics between resident and transient Killer Whales.

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


Most life history data about orcas has been obtained from long-term surveys of the population off the coasts of British Columbia and Washington and by monitoring captive orcas. Due to the completeness of the study and highly structured nature of the pods in this population, the information is detailed and accurate; however, transient groups and groups in other oceans may have slightly different characteristics. Females become mature at around 15 years of age. From then they have periods of polyestrous cycling with non-cycling periods of between three and sixteen months. The gestation period varies from fifteen to eighteen months. Mothers calve, with a single offspring, about once every five years. In analysed resident pods, birth occurs at any time of year, with the most popular months being those in winter. New-born mortality is very high — one survey suggested that nearly half of all calves fail to reach the age of six months. Calves nurse for up to two years, but will start to take solid food at about twelve months. Cows breed until the age of 40, meaning that on average they raise five offspring. Typically females live to the age of fifty, but may survive well into their eighties or nineties in exceptional cases. Males become sexually mature at the age of 15, but do not typically reproduce until age 21. Males live to about 30 on average, and to 50 in exceptional cases.

Range

The orca is the second-most widely distributed mammal in the world, after the human. They are found in all oceans and most seas including (unusual for cetaceans) the Mediterranean and Arabian Seas. Cooler temperate and polar regions are preferred, however. Although sometimes spotted in deep water, coastal areas are generally preferred to pelagic environments.

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

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

Fish-eating orcas in the North Pacific have a complex system of social grouping. The basic unit is the matriline, which consists of a single female (the matriarch) and her descendants. The sons and daughters of the matriarch form part of the line as do the sons and daughters of those daughters (the sons and daughters of the sons join the matriline of their mates) and so on down the family tree. Because females can live for up to ninety years, it is not uncommon for four or even five generations to travel together. These matrilineal groups are highly stable over many years. Individuals will only split off from their matrilineal group for up to a few hours at a time in order to mate or forage. No permanent casting out of an individual from a matriline has ever been recorded. The average matriline size as recorded in northeast Pacific waters is nine animals.

Matrilines form loose aggregations called pods, consisting on average of about 18 animals. Members of a pod all have the same dialect (see the section on vocal behaviour below) and consist of closely related matriline fragments. Unlike matrilines, pods will split apart for days or weeks at a time in order to carry out foraging before joining back together. The largest recorded pod is 49 animals.

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

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

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

The southern community (1 clan, 3 pods, 92 orcas as of 2005, counting Luna (L98))

The northern community (3 clans, 16 pods, 214 orcas as of 2000)

The south Alaskan community (2 clans, 11 pods, 211 orcas as of 2000)

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

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

Diet

 A male orca with its characteristic tall dorsal fin swims in the waters near Tysfjord, NorwayThe orca is an apex predator and the array of species on which orcas prey is extremely diverse. Specific populations show a high degree of specialization on particular prey species. For example, some populations in the Norwegian and Greenland sea specialise on herring and follow that fish's migratory path to the Norwegian coast each autumn. Other populations in the area prey on seals.

The orca is the only cetacean species to regularly prey on other cetaceans. Twenty-two species have been recorded as preyed on, either through an examination of stomach contents, examining scarring on the other cetacean's body, or by simply observing the feeding activity. Groups of orcas will even prey on larger cetaceans such as minke whales, gray whales, female and juvenile sperm whales or young blue whales. A group of killer whales take a young whale by chasing it and its mother through the sea, wearing them out. Eventually the orcas manage to separate the pair and surround the young whale, preventing it from returning to the sea's surface to breathe. Large whales are typically killed by drowning in this way.

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

The diet of killer whales shows substantial variation among different populations. Fish-eating populations prey on 30 species of fish, particularly salmon (including chinook and coho), herring, and tuna. Basking sharks, oceanic whitetip sharks, and very occasionally even great white sharks are taken for their nutrient-rich livers. Other marine mammals, including most species of seal and sea lion, are taken by mammal-eating populations. Walrus and sea otters are taken less frequently. Several species of bird are also taken, including penguins, cormorants and sea gulls. Cephalopods, such as octopuses and a wide range of squids, are also targets.

Possessing great physical prowess as well as intelligence, Orcas use complex hunting strategies to find and subdue their prey. They sometimes will throw seals to one another through the air in order to stun and kill the animal. While salmon are usually hunted by a single orca or a small group of individuals, herring are often caught using carousel feeding: the orcas force the herring into a tight ball by releasing bursts of bubbles or flashing their white underside. The orcas then slap the ball with their tail flukes, either stunning or killing up to 10-15 herring with a successful slap. The herring are then eaten one at a time. Carousel feeding has only been documented in the Norwegian orca population and with some oceanic dolphin species. Sea lions are killed by head-butting or by being slapped and stunned by a tail fluke.

A captive orca in Friendship Cove discovered that it could regurgitate fish onto the surface, attract sea gulls, and eat them. Other orcas then learned the behavior by example.

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


On average, an orca eats 500 lbs. (227 kg) of food each day.[4] With this huge variety of prey, and no predators other than man, the orca is very much at the top of the food chain.

Vocal Behaviour

 Orcas, like this one spotted near Alaska, commonly breach, often lifting their entire body out of the water.As with other dolphins, orcas are very vocal animals. They produce a variety of clicks and whistles that are used for communication and echolocation. The vocalization types vary with activity. While resting, perhaps unsurprisingly, they are much quieter, merely emitting an occasional call that is distinct from those heard when engaging in more active behaviour.

Fish-eating resident groups of killer whales in the Northeast Pacific tend to be much more vocal than transient groups living in the same waters. Scientists surmise that the main reason for this lies in the different hearing abilities of their prey. Resident killer whales feed on fish, particularly Pacific salmon, a prey with poor underwater hearing that cannot detect killer whale calls at any significant distance. Transient killer whales on the other hand feed mainly on marine mammals (primarily seals, sea lions, porpoises and dolphins) and occasionally on seabirds. Because all marine mammals have excellent underwater hearing, transients probably remain silent for much of the time to avoid detection by their acoustically sensitive prey. For the same reason, mammal-hunting killer whales tend to restrict their echolocation, occasionally using just a single click (called a cryptic click) rather than the long train of clicks observed in other populations.

Resident pods have group-specific dialects. Each pod has its own vocal repertoire or set of particular stereotyped underwater calls (call types). Every member of the pod seems to know all the call types of the pod, so it is not possible to identify a single animal using voice alone, only a dialectal group. A particular call type might be used by only one group or shared among several. The number of call types shared by two groups appears to be a function of their genealogical relatedness rather than their geographical distance. Two groups that share a common set of ancestors but have grown apart in distance are likely to have a similar set of call types. Calls are learned behaviour traits that are copied between related individals through vocal mimicry.

Orcas in history

Although only scientifically identified as a species in 1758, the orca has been known to humans since prehistoric times. The desert culture of the Nazca created a Nazca line representing an orca sometime between 200 BC and AD 600.

Indigenous tribes in the Pacific Northwest of North America such as the Tlingit, Haida, and Tsimshian featured the orca prominently in their religion and artwork.

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

 Mythologized orca and whales surround Thule on the Carta marina.Probably inspired by Pliny's description, creatures by the name of orca or "orc" have appeared throughout the history of Western literature. In Ludovico Ariosto's epic poem Orlando Furioso, the orca (sometimes translated "orc") was a sea-monster from whom the damsel Angelica was rescued by Orlando (Cantos 8 and 11), in an episode modelled on the story of Perseus and Andromeda. This Orca-like sea monster first appears in English in Michael Drayton's Polyolbion, an epic poem about Brutus the Trojan, the mythical founder of Great Britain. It later appears in John Milton's epic poem Paradise Lost; book 10 speaks of "The haunt of Seales and Orcs, and Sea-mews clang."

Hunting

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

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

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

Orcas are also occasionally killed out of fear of their reputation. No human has ever been attacked by an orca in the wild, but sailors in Alaska shoot the animal occasionally with concern for their own lives. This fear has generally dissipated in recent years due to better education about the species, including the appearance of orcas in aquariums and other aquatic attractions.



Co-operating with humans

More unusally, Orca have also be known to co-operate with humans in the hunting of other whales. One famous incidence of this was near the port of Eden in South-Eastern Australia in the 1920s. A pod of Orca, led by a dominant male called Old Tom, would assist whalers in hunting baleen whales - the Orca would find the target whales, shepherd them into Twofold Bay and then alert the whalers to their presence and often help to kill the whales. In return the whalers allowed the orcas to eat the tongue and lips of the whale before hauling it ashore.

The orca's intelligence, trainability, striking appearance, playfulness in captivity, and its sheer size have made it a popular exhibit at aquariums and various aquatic theme parks. The first orca capture and display took place in Vancouver in 1964. Over the next 15 years around sixty or seventy orcas were taken from Pacific waters for this purpose. In the late 1970s and the first half of the 1980s, orcas were generally taken from Icelandic waters (fifty in the five years to 1985). Since that time, orcas have been successfully bred in captivity and wild specimens are considerably rarer. Orcas in captivity may develop pathologies such as dorsal fin collapse, seen in 60-90% of captive males.

There have been incidents with orcas in captivity attacking humans. In 1991, a group of orcas killed a trainer named Keltie Byrne at Sealand in Victoria, British Columbia (where employees were not allowed in the water with orcas), apparently not knowing she could not survive underwater. In 1999, at the SeaWorld park in Orlando, Florida, one of the same orcas allegedly killed a tourist who had snuck into the orca's pool at night[5]. (The dead tourist, who was otherwise physically unharmed, was also thought to be a victim of hypothermia.) In late July 2004, during a show at the SeaWorld park in San Antonio, Texas, an orca pushed its trainer of ten years underwater and barred the way to the rim of the pool; the trainer could only be rescued from the raging animal after several minutes.

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

SeaWorld continued to be under criticism from the Born Free Foundation over its continued captivity of the orca Corky II, who they want to be returned to her family in the A5 Pod—a large pod of orcas in British Columbia, Canada [6].

Orcas in captivity have vastly reduced life expectancies, on average only living into their 20s whilst in the wild females may live into their 80s. The captive environment also bears no resemblance to their wild habitat and the social groups that the orcas are put into are completely foreign to reality [7]. Critics claim that the captive life of an orca is stressful due to small tanks, false social groupings and chemically altered water. Organisations such as the WSPA and the Whale and Dolphin Conservation Society campaign against the captivity of Orcas.

Popular culture

 The Vancouver Canucks logo from 1996 to present.As late as the 1970s, orca were depicted negatively in fiction as ravenous predators whose behavior caused heroes to interfere to help a prey animal escape. The poorly-received film Orca features the story of a male orca going on a vengeful rampage after his pregnant mate is killed by humans. Many consider this an obvious attempt to duplicate the success of Jaws, although it can also be considered to show the animals as being (perhaps unrealistically) much more like humans, with intelligence and a great capacity for love and tenderness as well as vengeance.

However, the increased research of the animal and its popularity in public venues brought about a dramatic rehabilitation of the animal's public image. The sentiment about the animal grew to more as a respected predator that poses little actual threat to humans, much as the North American wolf's image has been changed.

The film Free Willy (1993) focused on the quest for freedom for a captive orca. The orca starring in the movie, Keiko, was originally caught in Icelandic waters. After rehabilitation at the Oregon Coast Aquarium in Newport, Oregon, he was later returned to the waters of the Nordic countries, his native habitat, but continued to be dependent on humans until he died of pneumonia in December 2003.

A coast-salish styled orca (above) has also been the logo of the NHL's Vancouver Canucks hockey franchise since they changed jerseys in the 1996-97 season. This logo is an orca breaking through cracked ice, in the shape of a "C". This is likely a reference to OrcaBay, the company which owns the team. The team mascot is also an orca named "Fin".

Environmental threats

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

Like other animals at the highest trophic levels of the food chain, the orca is particularly susceptible to poisoning via accumulation of Polychlorinated biphenyls (PCBs) in the body. A survey of animals off the Washington coast found that PCB levels in orcas were higher than those in harbour seals in Europe that have been sickened by the chemical. Samples from the blubber of orcas in the Norwegian Arctic show higher levels of PCBs, pesticides and brominated flame-retardants than in Polar bears. However, no direct evidence of sickness in orcas has been found. The most likely effect, if any, would be a reduced rate of reproduction or decreased ability to fight off disease (immunodepression). On November 15, 2005 the United States government listed the Southern Resident population of killer whales as an endangered species under the Endangered Species Act (ESA) due to deterioration of the three pods which spend most of the year in Georgia and Haro Straits, as well as Puget Sound in British Columbia and Washington State.

Other environmental pressures facing killer whales include extensive whale watching which some research indicates changes orca behavior. Heavy ship noise can interfere with the acoustic communication and echolocation of killer whales.

Famous Orcas

Keiko — performed in the first of the three Free Willy movies.

Shamu — performs along with Baby Shamu and Grandbaby Shamu at SeaWorld

Lolita — Only surviving (Captive) member of the L pod Capture in 1964 she still resides at the "Miami Seaquarium"

Namu - One of the first orcas in an aquarium exhibit, (Seattle, WA), 1965. Star of a semi-documentary named after him, changed a lot of people's attitude's towards orcas.[8] Namu developed a bacterial infection which damaged his nervous system causing him to become non-responsive to people. During his illness he charged full speed into the wire mesh of his pen, thrashed violently for a few minutes and then died.

References 

Bonner, Nigel. 1989. Whales of the World. Facts on File, Inc., New York. 191 pp.

 Gormley, Gerard. 1990. Orcas of the Gulf. Sierra Club Books, San Francisco. 205 pp.

 Walker, Ernest P. 1975. Mammals of the World. Third Edition, Volume II. The JohnHopkins University Press, Baltimore. 647-1500 pp.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Olympic BMX

BMX Track: All you need to know about the venue for one of the Games newest sports

 

The 400-metre circuit is located next to the Velodrome, and will host two-days of BMX cycling action from today.
Location: In the north of the Olympic Park
Capacity: 6,000
Sport: BMX Cycling
First event: Men's and women's seeding phase (Aug 8)

BMX made its debut at the Olympic Games in Beijing four years ago

The track will be available to the community after the Games

Schedule: BMX: Aug 8 - Aug 10

Okay, so yet another Olympics related post. BMX racing is not only a nostalgic part of childhood for us Gen X’ers and Y’ers, its the newest sport to be added to the Olympics – making its debut this week in Beijing.

I really wouldn’t be surprised that the so-far-terrible Channel 7 Olympic coverage to completely ignore this sport – but they really shouldn’t. Why? because we have 5 Australians competing in the BMX events.

We’re hoping to see Jared Graves (who came 2nd in the 2008 World BMX Supercross) and probably-not-his-birthname, Kamikazi (who was a semi-finalist in the 2008 BMX World Championship) make it into the finals. In which case we are almost guaranteed some live coverage on TV. And not to mention we’d love to see them thrash the Americans, who are expected to dominate the in these BMX events.

 

 

Shanaze Reade from England is also tipped for the gold medal.

The basics

The BMX races at London 2012 will be held on a short outdoor track, with the riders starting on an 8m-high ramp. Each race lasts around 40 seconds.

BMX bikes have only one gear and one brake. Most racing riders use wheels that are 20 inches in diameter – roughly two-thirds the size of wheels used on a standard road bike. Bikes need to be strong enough to endure the wear and tear from the jarring landings after jumps, yet light enough to remain fast and competitive.

Competition format

The men's and women's events at London 2012 both start with a seeding phase: each rider runs the track once to determine the seedings, which ensures that the fastest riders don’t meet before the final.

The women progress straight to the semi-finals and the men’s event continues with the quarter-finals, which are held over five runs, with points for places on each run. After three runs, the best two riders from each quarter-final progress to the semi-finals. The remaining riders compete in the final two quarter-final runs and the best two from each quarter-final also progress to the semi-finals.

From here, the semi-finals in both the men’s and women’s events follow a three-run format. The top four riders from each semi-final advance to the final, where the medals are decided over one run.

Officials

Officials include inspectors, who ensure that all bikes conform to International Federation regulations, start and finish officials, and race officials, who are stationed along the course and ensure riders adhere to all rules and regulations.

Keys to success

BMX riding is fast and furious and riders must be daring and fearless. Although short, the track is demanding and the winning riders must be able to beat the field and stay out of trouble. 

Breaking the rules

The race officials are on the lookout for any infringements, such as deliberately interfering with another rider, coming into contact with other riders or obstructing their racing line in the final straight. Officials can issue a warning, with two warnings resulting in disqualification. They also have the power to relegate a rider to last place in a particular run, regardless of where the rider actually came. 

 

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