- Scientific name: Orcinus orca
- Also know as: Orca, Grampus, The Blackfish
- Size: Up to 10 metres in length and 10 tons, but typically 7-8 metres in length for males and 6-7 metres for females.
- IUCN Status
- Global: DD (Data Deficient)
- Europe: DD (Data Deficient)
- Distribution: One of the world’s most widely distributed mammal species, being found in all of the major seas and oceans of the world.
- Feeds on: Mostly fish and squid but also known to take a range of other creatures including other whale and dolphin species, seals, sea lions, large sharks and tuna, marine birds and even large land-dwelling mammals which enter water such as moose and deer.
- Description: Very large marine mammal with powerful, robust body. Colouration differs depending where on the world the individual killer whale is from but is mostly black with white patches and a distinct grey spot behind the dorsal fin, known as the ‘saddle’. Blowhole, which is covered by a muscular flap, is located at the top of the head. The dorsal fin is very tall in males – it can be over two metres high – and around a metre in females. Mouth is large and full of sharp, interlocking teeth which can be several inches in length.
Killer whales are an instantly recognisable species of marine mammal due to their striking black and white colouration. They are widely found throughout the seas and oceans of the world and have a high profile in the public consciousness the world over due to the use of killer whales in design products and culture. Killer whales are fierce predators which will attack and eat almost any form of animal which they find, although they have never been known to kill a human in the wild. Killer whales are kept in captivity in some parts of the world, although this is extremely controversial and a number of captive killer whales have been known to display uncharacteristic behaviour such as attacking – and in some cases killing – their trainers and handlers.
Killer whales have an extremely extensive distribution, being found in all of the worlds seas and oceans from the Arctic Ocean and polar regions to the Caribbean, Mediterranean and tropical areas of the Pacific. This makes them one of the most widespread animals in the world, with killer whales only absent from enclosed or almost enclosed bodies of water such as the Black Sea and the Caspian Sea. Killer whales tend to prefer water which is at least 20-30 metres deep, and can often be found around areas where there is sloping continental shelves.
Many people are surprised to hear that killer whales are present in the waters around the British Isles but they are indeed, and there is in fact a resident British population off the west coast of Scotland. This pod, however, consisted of just nine killer whales and was reduced to eight in 2016 when ones of the female killer whales known as Lulu died after becoming tangled in commercial fishing gear. The British killer whale pod is seen as being isolated from wider populations of killer whales, and consists entirely of older killer whales with the females all being past the age where they can reproduce. This, along with the lack of lack of interaction with other killer whale pods means that it is therefore sadly inevitable that the British population will die out in the coming years.
Killer whales live in pods ranging from as few as six killer whales to as many as several hundred. Although there are different types of killer whale groups (see below) all groups have a complex social structure, often with a clear hierarchy. Some pods of killer whales are thought to have the oldest and largest male acting as a leader, although this is poorly understood, whereas other males have been known to leave pods a live a mostly solitary life, meeting with pods only to breed. Killer whales communicate with each other using a series of clicks, whistles and grunts, and also use echolocation for hunting prey and learning about their surroundings.
Like all marine mammal species killer whales care for their young and many young killer whales stay with their mothers until they are old enough to breed and have young of their own. Mothers have been known to fight to defend their young when they are threatened, especially when the young are very small. The life expectancy of killer whales is not fully known but it is thought that in the wild they can live for at least 60 to 70 years, and maybe up to the age of 100.
Killer whales are so called due to the predatory nature of this species, and for many centuries killer whales have had a reputation as a fearsome predator. Over two thousand years ago the Roman author, philosopher and military commander Pliny the Elder described killer whales as “an enormous mass of flesh armed with savage teeth.” Indeed, the scientific name for this species is derived from Orcus – the god of the underworld in Roman mythology – and translates as ‘bringer of death.’
However, this reputation is somewhat undeserved. While killer whales will attack and kill large creatures including other species of whale and even great white sharks there has never been a confirmed human death caused by killer whales and the very few attacks which have been reported are usually put down to killer whales misidentifying humans as seals or other creatures. Furthermore, the use of the name orca is also more accurate because the killer whale is not technically a whale species at all, but is a member of the dolphin family.
Species Classification and Different Species of Killer Whale?
Killer whales have a somewhat confusing species classification as they are known as whales but, as members of the Delphinidae family they are a species of dolphin. Indeed, killer whales are the largest member of this family.
Killer whales are currently classed as a single species – Orcinus orca. However, this is disputed and it is believed by the scientific community that there are in fact different species of killer whales. It is believed that there are resident killer whales which live near land in tightly defined family structures, transient killer whales which live in small groups, and offshore killer whales which live in large pods out in the open ocean. There are also different types of killer whale based on different black and white colourations and different locations/patterns of the grey saddle behind the dorsal fin. The resident British population, for example, seems to be physically different to other Atlantic and Pacific killer whales as they are larger and have different teeth patterns.
The IUCN (International Union for the Conservation of Nature) state that one of their reasons for classing killer whales as Data Deficient is because of this confusion over the classification of the species. While there is no consensus over the status of killer whales species it is impossible to come up with solid conclusions over the state of species numbers. The IUCN’s website currently states: “[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 sub-species over the next few years.”
Like other large marine mammals (such as humpback whales) very rare completely white albino killer whales also exist. These albino killer whales appear to be accepted into pods without problems.
Other Species with the ‘Killer Whale’ Name
Several other species share the killer whale name, even though they are very different in appearance – and not closely related – to the more widely known Orcinus orca.
The pygmy killer whale (Feresa attenuata) is a rarely observed and little known species which is found in the warm waters around the equator and is not present around the British Isles. It grows to a maximum length of around seven feet in length and is thought to feed mostly on fish and squid. It is thought to be an aggressive predator which will attack fish and other cetaceans much larger than themselves. When kept in captivity they have been observed fighting with other pygmy killer whales kept in the same area and displaying extremely aggressive behaviour. In the wild they have been seen in pods of a few whales to over one hundred, but very little is known about their life cycle or social interactions. The pygmy killer whale is classed as Data Deficient by the IUCN.
The false killer whale (Pseudorca crassidens) is a large species of the dolphin family which is mostly present in the warmer tropical and subtropical waters around the equator. They have been sighted in British waters from time to time but are a rare visitor, and most false killer whales found around the UK are though to be vagrants. They grow to maximum lengths of 18 to 20 feet and can weight several tons. They do not actually look much like a killer whale and it is mostly the shape of the head and jaw which give this species its similarly to the orca killer whale. Like most species of this type they feed on fish and squid, and due to their size they have also been known to feed on large fish such as tuna and even other marine mammals such as seals and immature whales and dolphins. False killer whales are hunted by a number of nations – particularly Japan – for their meat and oil. They are also caught in fishing gear and are thought to be affected by the powerful sonar used by military vessels. Numbers are thought to have dropped significantly in recent years with this species being sighted much less than in recent years. However, due to the lack of information and research on this species they are classed as Data Deficient by the IUCN.
Killer whales are aggressive predators which have been known to feed on a huge range of sea creatures. While most killer whales feed on fish (anything from herring and mackerel to cod, tuna and small sharks) some killer whales – such as the resident British population – are thought to feed on other marine mammals such as seals and porpoises. Intelligent behaviour is displayed by feeding killer whales – they will partly beach themselves in order to catch seals in shallow water, and have been observed waiting for marine birds to settle on the surface before launching themselves upwards to catch them. They have also been seen swimming rapidly past ice on which young seals are sitting to create a bow wave which washes the seals into the sea and allows the killer whales to easily eat them. Killer whales also hunt in packs to attack and kill large prey. They have been observed killing large shark species such as mako sharks and have even been known to attack and kill some of the largest creatures in the sea (such as whale sharks and sperm whales) as well as some of the most fearsome predators (such as great white sharks). Killer whales are extremely active predators they will ram into prey (they can swim at speeds of up to thirty miles per hour) to stun and disorient prey before attacking, and will leap out of the water to herd prey towards the rest of their pod – this newspaper article contains amazing pictures of killer whales jumping 15ft out of the sea to catch a bottlenose dolphin off the coast of Mexico. Unusual prey is also taken by killer whales. They have been known to attack and kill large land mammals such as moose and deer when they have been swimming between islands in Alaska and Canada.
However, the range of different animals which killer whales prey on does not mean that they are voracious feeders. Often killer whales will kill prey and then only consume part of it. For example they have been seen killing large whales and then only eating the liver or tongue and then allowing the rest of the carcass to fall the the seabed. Killer whales also kill other marine mammals for no apparent reason – behaviour which scientists and marine biologists are still trying to understand. In 2001 the BBC television programme Blue Planet captured footage of a pack of killer whales chasing a grey whale calf and its mother for over six hours. Once the 20ft calf was separated from its mother the killer whales eventually drowned it by forcing it under the water for several minutes. However, once the calf was dead the killer whales then only ate the calf’s tongue and lower jaw, allowing the rest of the calf’s carcass to go to waste despite the large amount of time and effort that was spent catching it. Again, the reasons for this type of behaviour are unknown. The initial part of the attack from the Blue Planet TV programme can be viewed on YouTube here.
Attacks on Humans and Human Interactions
Despite the fact that killer whales are extremely large predatory species attacks on humans are very rare – there has never been a confirmed report of a killer whale causing a fatal attack on a human in the wild (the situation with killer whales in captivity is very different – see below). As previously stated it thought that killer whale attacks on humans are often due to mistaken identity. For example killer whales have been known to attack surfers, presumably because they mistake the shape of a surfboard for a seal, while the reasons for other ‘attacks’ on humans have been described as being caused by the inquisitiveness of killer whales, or because the killer whales have attempted to play or interact with humans.
There have even been reports of killer whales helping humans to catch other whale species. A famous example of this comes from Australia’s south east coast where a killer whale known as Old Tom would help whaling vessels by herding migrating blue whales and humpback whales towards the vessels.
He was also known to apparently assist sailors who fell into the sea. As a reward Old Tom was allowed to eat the tongue and lips of the killed whales before the vessels brought the carcasses on board. Read more about Old Tom here. However, in other parts of the world commercial fishermen have been known to hunt killer whales due to the perceived damage that this species does to fish stocks.
Killer Whales in Captivity
Related article: Captive Killer Whales
Due to their size, appearance and the fact that they can be trained to take part in spectacular shows, killer whales are a popular species to keep in captivity. The huge sizes that killer whales can grow to means that only the largest marine parks have the facilities and resources to house killer whales, with trained killer whales often putting on shows involving ‘water work’ (shows where trainers swim with and ride on the backs of killer whales, and get the killer whales to swim and jump out of the water in a synchronised manner) as part of shows for the tourists and visitors who attend these parks.
However, keeping killer whales in captivity is massively controversial for a number of reasons. Killer whales are used to living in the open ocean where they may swim up to one hundred miles per day, even the largest tanks and aquariums made up of different pools containing many millions of gallons of water cannot come close to replicating the conditions killer whales naturally live in. Conservationists point to a clear physical change in captive killer whales – the dorsal fin, which is very large (over six feet high in fully grown male killer whales) and upright in wild killer whales almost always collapses and flops to one side in male captive killer whales, and occasionally in females as well. The reasons for this are unknown, with theories put forward stating that the lack of space to swim in, the amount of time captive killer whales spend on the surface and the stress of being kept in captivity all put forward as reasons.
Marine parks such as Seaworld in the USA state that a collapsed dorsal fin is not an indicator of poor health, and claim that killer whales do not need their dorsal fins for swimming or balance anyway.
However, it is the lack of interaction with other killer whales which conservationists point to as the main reason why it is unacceptable to keep killer whales in captivity. As stated above wild killer whales live in pods with extremely complex social structures. Males and females have specific roles within the group and females care for young for many years after birth. Pods may stay together for the entirety of their lives. Taking killer whales from the wild breaks up these social structures and causes immense amounts of stress for both the captured whales and the remaining pod, while killer whales born in captivity never get the chance to make the family and group connections which they are biologically programmed to do. This leads to conservationists claiming that the stress of captivity and being made to train and perform causes all captive killer whales to eventually enter a state of psychosis leading to aggressive and extremely damaging behaviour. Evidence for this can be seen in the fact that while killer whales in the wild have never killed a human, those kept in captivity have killed several. Tilikum, a killer whale captured in Icelandic waters in 1983 and currently housed in Seaworld in Orlando, Florida, has killed one trainer and been involved in the deaths of two other people. Due to these events some marine parks such as Seaworld have been legally banned from carrying out water work with killer whales due to the danger which the trainers are placed in. Although SeaWorld initially fought this and defended keeping killer whales in captivity the pressure on the company has increased in recent years. In March 2016 SeaWorld announced that it was phasing out the live shows featuring killer whales and would not breed any further killer whales in its parks, meaning that the current generation of killer whales in captivity will be the last.
Further evidence that killer whales are unsuited to life in captivity comes from the fact that the vast majority of all types of animal generally have a higher life expectancy when kept in captivity (due to the protection from predators, easy availability of food and the medical care etc). However, killer whales can live for 60 to 70 years in the wild and may even be able to live up until 100 years. In captivity killer whales reaching 40 are considered old, and many only live until their late 20s. The number of calves who are stillborn or die in the first few days of life is also much higher in captivity than it is in the wild. One of the most famous attempts to re-introduce a killer whale into the wild took place in the late 1990s. Keiko was the star of the hugely successful 1993 film Free Willy. The publicity this film generated led for calls to Keiko to be released back into the wild. The was attempted, although the results were not entirely successful. Read more about the story of Keiko by clicking here.
The 2013 film Blackfish explores the issues around killer whales kept in captivity and is available to buy from Amazon by clicking here.Read our full article on killer whales in captivity by clicking here.
Hunting, Conservation Efforts and IUCN Status
Killer whales have been hunted by humans for hundreds of years, although never at the intensity of other species of whale. This is because killer whales do not contain anywhere near the same amount of useful oil when compared to other whale species such as sperm whales and blue whales. Killer whales are not currently hunted in high numbers by any nation, although a number of killer whales may be taken by countries which persist in killing large marine mammals such as Greenland and Japan.
Threats to killer whales include pollution, a dwindling food supply and killer whales becoming trapped in the nets of commercial vessels. However, these issues are not presently thought to have a great impact on killer whale numbers. Despite the Data Deficient classification (due to the confusion over the status of this species, see above) that the IUCN gives this species it is believed that numbers of killer whales are relatively healthy.
Killer whales are of great interest to the scientific and marine biology community. Like all marine mammals the social structure of killer whale pods and the communication between individuals are still poorly understood and require greater research. Furthermore the indeterminate species classification of killer whales is another area which require attention. Although there is no timescale it is near-certain that killer whales will be split into a number of different species or sub-species in the near future.