Killer Whale

  • Scientific name: Orcinus orca
  • Also know as: Orca, Grampus,  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: 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 dolphin species, seals, sea lions, sharks and tuna.
  • Description: Very large marine mammal with a powerful, robust body. Colouration differs but is mostly black with white patches and a distinct grey spot behind the dorsal fin. 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. The 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 Whale Distributon
Killer whales are one of the most widely distributed mammal species in the world.

Killer whales have an extremely extensive distribution, being found in all of the world’s seas and oceans. This makes them one of the most widespread animals in the world, with killer whales only absent from enclosed and semi-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.

British Population

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 usually found off the west coast of Scotland. This pod consisted of just nine killer whales and was reduced to eight in 2016 when ones of the female killer whales known as Lulu was found dead tangled in commercial fishing gear. Analysis of the killer whale found extremely high levels of chemicals and pollutants known as PCBs in her body, which may have been the cause of death. There are fears that the rest of the pod may have similar levels of chemicals in their bodies. In the spring of 2021 the pod was spotted outside of their usual home, this time off the coast of Cornwall. The resident British killer whales have not produced a calf since monitoring began in the 1990s and there are fears that they may be infertile due to their exposure to PCB chemicals and other forms of pollution.

In April 2018 a separate pod of six killer whales was spotted in the River Clyde in Scotland. The pod consisted one bull, one calf and four female killer whales and swam up the Clyde as far as the Erskine Bridge, possibly following sources of food such as seals or fish. The killer whales eventually exited the river and made their way back out to sea and into deep water. A further British sighting of killer whales was made the following month when a lobster fisherman spotted another pod of killer whales six miles out to sea off the coast of Northumberland. In January 2019 a killer whale known as John Coe – which can be identified by missing sections of its dorsal fin – was spotted in the Moray Firth. John Coe was accompanied by a second killer whale which conservationists and marine scientists were not able to identify. In May 2020 a group of killer whales were spotted off the coast of Northumberland near to Holy Island by commercial fishermen who were collecting lobster pots. It is unknown if this was the same pod which had previously been sighted in the area.

Life Cycle

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 all groups have a complex social structure, often with a clear hierarchy. 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.

Killer Whale Pod
Four killer whales from a pod in the Ross Sea, Antarctica.

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 reproduce 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 possibly up to the age of 100.

Common Names

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. The very few attacks on humans 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 a whale species at all, but is a member of the dolphin family.

Species Classification and Different Species of Killer Whale?

Pod of Killer Whales
There is currently a great deal of speculation over how killer whales should be classified.

Killer whales are currently classed as a single species – Orcinus orca although this is disputed and it is believed by the scientific community that there are in fact several 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 subspecies over the next few years.”


Killer Whale Skull
Killer whale skull showing the large, sharp teeth that this species possesses.

Killer whales are aggressive predators which have been known to feed on a wide range of sea creatures. While most killer whales feed on fish some killer whales – such as the resident British population – are thought to feed on 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 observed knocking seals from ice by swimming rapidly past to create a bow wave which washes the seals into the sea. Killer whales also hunt in packs to attack and kill large prey. They have been seen killing large shark species such as mako sharks and have even been known to attack and kill 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. 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.

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 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. 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.

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.

Old Tom
Old Tom (foreground) and a calf follow a whaling boat which is being towed out to sea by a large whale (not visible in the picture) they have harpooned. Photo is from the year 1912.

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. 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 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.

Killer whale water work
Captive killer whales are often trained to take part in ‘water work’, although in the USA this is currently banned following the deaths of several trainers.

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.

Collapsed dorsal fin
Captive killer whale with a collapsed dorsal fin.

Marine parks such as Seaworld in the USA maintain 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.

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 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 of stress for both the captured whales and the remaining pod. Conservationists claim 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 was housed in Seaworld in Orlando, Florida until its death in 2017. Tilikum killed one trainer and was 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 animals of all types held in captivity generally have a higher life expectancy than those in the wild due to protection from predators, easy availability of food, medical care and so on. While wild killer whales live until their sixties or seventies captive killer whales usually die in their twenties, with Tilikum living slightly longer until the age of 35. 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 as much useful oil when compared to other whale species such as sperm whales and blue whales. Killer whales are not currently hunted in high numbers, although a small number may still be taken each year by whale hunting nations such as Greenland and Japan.

Orca Biopsy Dart
A US NOAA (National Oceanic and Atmospheric Administration) researcher fires a harmless biopsy dart into a killer whale in order to take a tissue sample.

Threats to killer whales include pollution, a dwindling food supply, entanglement in the nets of commercial vessels and being struck by ships. These issues are not presently thought to have a significant impact on killer whale numbers and the extremely wide distribution of this species helps maintain numbers. Despite the Data Deficient classification being given by the IUCN (due to the confusion over the status of this species, see above) it is believed that numbers of killer whales are relatively healthy.