Orca

    • Derivation of scientific name

    The genus name Orcinus is a Latin word that means ‘kingdom of the dead’ or ‘belonging to the Orcus’. In Roman mythology, Orcus is a god of the underworld and was depicted as a grim and fearsome deity who ruled over the realm of the dead. Thus, the name Orcus was given to the orcas because of their reputation as powerful and formidable predators, evoking a connection to the fearsome nature of the Roman god of the underworld.

    Common names: Orca, killer whale, blackfish, wolve-of-the-sea (Eng.); moordwalvis (Afr.).

    Introduction

    Orcas, also known as killer whales are large marine mammals and the largest members of the dolphin family. Despite the common name ‘killer whale’ they are not whales, but a type of dolphin, and therefore the name ‘orca’ is preferred. Orcas are apex predators and are perceived to be one of the most intelligent species in the ocean, with complex social structures, sophisticated communication and problem-solving abilities.

    After sperm whales, orcas have the largest brain and have more grey matter and neurons than any other mammals, including humans. Orcas are fascinating creatures, with strong social ties and complex emotions. They are depicted in mythology and have cultural connotations. People who have interacted with them offer unique stories that demonstrate their intelligence, playfulness, curiosity and, at times, ruthlessness.

    Description

    Orcas are easily recognisable with their distinctive black and white body. The orca is mostly black with large white patches around the body. Males are larger than females, ranging from 6 to 8 m long and can weigh anywhere between 6 000 and 10 000 kg, while females are 5–7 m long and can weigh between 3 000 and 4 000 kg. Newborn orcas weigh 180kg at birth and are about 2 m long. Their bodies are smooth and streamlined and is covered in a layer of blubber (fat) under the skin. This helps them with buoyancy and insulation in cold marine environments.

    Orcas have three main types of fins on their body: dorsal fin, pectoral fin and tail flukes. They have powerful jaws and teeth, and their upper teeth and lower teeth are misaligned so that when they close their mouth the upper teeth fall into the space between the lower teeth. This allows for efficient grasping and tearing of prey.

    Orcas cannot breathe underwater and must come up for air to get oxygen, because unlike fish, they cannot extract oxygen from the water. Therefore, orcas’ have a blowhole (an opening) at the top of their head which allows them to inhale and exhale air at the surface of the water. They have powerful lungs and can hold their breath for several minutes, but eventually, they need to return to the surface to breathe.

    Presently, scientists have determined that there are different populations of orcas that are referred to as ecotypes. These ecotypes or populations differ in diet, appearance, genetics and behaviour. Currently, there is not enough information about each of the different populations to determine whether they can be considered sub-species or separate species entirely.

    Pic: Ryan Stone

    Getting around

    Orcas are capable of powerful and agile movements, their locomotion methods include swimming, diving and breaching. An interesting behaviour observed in orcas is breaching, this is when they leap out of the water and crash back down with impressive force. The exact purpose of breaching is not well understood; however, it could be for purposes such as communication, social bonding, hunting or play.

    To facilitate these movements in an orca, they have three fins on their body that work together to enable the powerful movements: a dorsal fin which helps with stability, pectoral fins for steering and manoeuvring and tail flukes for propelling the animal through the water.

    Communication

    Orcas have fascinating and advanced communication skills. They use underwater calls for orientation, feeding and communication. They use three primary sounds: clicks, whistles and pulsed calls10. Interestingly, within each pod, all members use similar calls, which is called a dialect and is unique to each pod11. This dialect is learned and is passed down from generation to generation.

    This contributes to the identity and social bonding of the pod. The dialect can be used, for example, if an orca calf is lost or separated from its pod. The pod members can issue a call and the calf can recognise the distinct vocalisations of its pod enabling the lost orca calf to be reunited with its pod.

    Distribution

    Orcas have a cosmopolitan distribution and are found in every ocean over the planet from the Arctic to the Antarctic. While not as common as in the Pacific Northwest, orcas have been observed along South Africa’s coastlines. They are commonly found in the Cape Peninsula and the Western Cape region, with sightings in Cape Town, False Bay and along the Garden Route.

    Two famous orcas that made the headlines were a pair of male orcas named Port and Starboard. They made the headlines for their precise hunting and feeding behaviour and were situated along the coast of South Africa. Read more about Port and Starboard and why they made the headlines in the ‘Food’ section below. 

    Habitat

    Orcas are found in all oceans and exist in a variety of marine environments. They exist in open oceans as well as coastal environments. They are commonly found in colder regions such as the Arctic, Antarctica, Norway, and Alaska as there is an abundance of prey species in these areas.

    Pic: Andre Estevez

    Food

    Orcas are called ‘wolves-of-the-sea’ because they hunt in groups like wolves. They are apex predators and therefore have no natural predators. Orcas has a diverse diet, and can eat fish, seals, penguins, sharks, dolphins, other whales or squids. However, their diet depends on the ecotype, availability of prey, and culture based on what they were taught to hunt and feed on as hunting skills are passed down through generations.

    For example, one ecotype may only eat fish, while another ecotype may exclusively feed on squids. A pair of male orcas named Port and Starboard have been famous for their ruthless predation of the great white shark off the South African coastline. This pair hunted and killed great white sharks removing only the sharks’ livers. This demonstrates an orca’s intelligence, coordination and precision feeding skills.

    Sex and life cycles

    The lifespan of female orcas is averaged to 50–80 years old whereas in males it ranges from 29 to 60 years. Female orcas reach sexual maturity at around ten years old and can breed up to age 40 while males reach maturity at 10–13 years.

    Typically, males mate with females from other pods to prevent inbreeding and increase genetic diversity. Female orcas can give birth to one calf once every five years. All pod members participate in taking care of the young. Calves learn by observing and imitating their mother and other pod members, learning essential skills in hunting, social behaviours and communication. This way, knowledge and skills are transferred to the next generation.

    Family life

    Orcas have complex and fascinating social structures. They are extremely social animals and they live together in family groups called ‘pods’. These pods are led by the oldest female orca known as the matriarch. The social structure consists of the matriarch, her offspring (both sons and daughters), and the descendants of her daughters.

    The matriarch holds the leadership position within the pod and plays a central role in decision making and group coordination. A single pod can have multiple families living together, with each family spanning as many as four generations. These family groups or pods remain cohesive throughout their lives.

    The attachment between pod members is strong but especially between the calf and their mother. A young calf and the mother typically swim side by side and always maintain close proximity. The separation between a mother and her calf can be emotionally devastating to both. An example of this bond being broken is the case of Katina and her daughter Kalina.

    Katina and Kalina were both captive orcas at SeaWorld Orlando, Florida. Kalina was the first orca to be born and raised in captivity. At the four years of age Kalina was separated from her mother, Katina, and moved to SeaWorld, Ohio. Katina allegedly spent the night alone, inconsolable, in the corner of the tank, trembling and emitting heartbreaking vocalisations, calling out for Kalina.

    THE BIG PICTURE

    Friends and foes

    Orcas are apex predators; this means that they have no natural enemies. In fact, their only enemy is humans as they are captured or killed in some parts of the world. As different ecotypes have a specific prey that they consume, it can have a dramatic impact on the prey species. For example, in the case of Starboard and Port, their tendency of eating only the livers of great white sharks have resulted in the shark population declining as well as the sharks fleeing from the region.

    Smart strategies

    Orcas are very successful apex predators due to specific adaptations such as:

    1. Hunting strategies: orcas are extremely skilled hunters, they hunt in their family groups and coordinate their attack to kill with accuracy and precision.
    2. Physiological adaptations for breathing: Unlike humans, orcas do not have an automatic breathing system. Breathing for orcas is a conscious process. This means that they must remember to breathe, even when sleeping! To achieve this, they utilise a sleeping method known as unihemispheric sleep. This is when they sleep by shutting down only one hemisphere of their brain at a time. As one half of their brain enters a sleep state, the corresponding eye on the opposite side of the body closes, while the other eye remains open and vigilant. If they did not have this adaptation, the orca would drown.
    3. Social structure and communication: orcas exhibit a complex social structure characterised by close family bonds and cooperative behaviour as mentioned above. The strong social bonds within pods foster cooperative hunting strategies, knowledge sharing and the transmission of learned behaviours, contributing to the overall success of the group as apex predators.
    4. Physical adaptations: Orcas possess a range of physical adaptations that optimise their hunting prowess in marine environments. Their powerful bodies enable swift and agile movements through the water, essential for pursuing and capturing prey.

    Poorer world without me

    Orcas as apex predators influence the behaviour and distribution of species in the ocean. Orcas regulate populations of prey species such as fish, seals, sharks or sea lions. Their predation on certain prey species may indirectly benefit other species by reducing competition for resources.

    They can also help in controlling the spread of invasive species. Furthermore, the fear of predation by orcas can alter the behaviour of prey species, leading them to modify their foraging patterns and habitats. This, in turn, can have ripple effects throughout the ecosystem, shaping the abundance and distribution of organisms at various trophic levels.

    People and I

    There are many myths, legends, cultural and spiritual beliefs that surround orcas. The Haida culture of British Columbia, Canada, regards orcas as supernatural beings that rule the ocean and have their own towns and villages under the sea. In some indigenous cultures, orcas are thought to be the rulers of the sea and have sea lions for slaves and dolphins as soldiers.

    In other cultures, orcas are seen as the reincarnation of a former chief of a tribe. For example, an orca named Luna, also known as Tsux’itt, was separated from his pod and spent five years in an ocean inlet of Vancouver Island. The Mowachaht/Muchalaht First Nations believed Luna/Tsux’itt was the reincarnation of their former chief who had died and had come back to them in the form of an orca.

    While orcas are seen as one of the ocean’s most dangerous creatures, there has never been a recorded attack of a human by an orca in the wild. However, there have been reports of orcas in captivity killing humans. Most famous was the case of Tilikum, who was captured as a two-year old calf and kept captive at SeaWorld Orlando, Florida for entertainment until he died. Tilikum was involved in the deaths of three people; Keltie Byrne, Daniel Dukes and SeaWorld trainer Dawn Brancheau18.

    The case of Dawn Brancheau was heavily publicised with the documentary ‘Blackfish’, which told the story of Dawn and Tilikum. After the release of Blackfish, SeaWorld was highly criticised for having orcas for entertainment purposes. Owing to an orcas’ close social ties, intelligence and size, there are questions surrounding the ethics and humanity of keeping an orca captive to perform circus tricks for humans’ entertainment, which is, quite frankly, insulting and cruel to a highly intelligent creature like an orca.

    Animal activists and marine biologists theorise that the attack of humans by orcas in captivity is partly caused by the frustration of being kept in the confines of a small tank, which affects their mental and physical health.

    Conservation status and what the future holds

    Conservation of this species has proved to be challenging as there has been some uncertainty whether all orcas are the same species or different species. The current International Union for Conservation of Nature (IUCN) status of Orcinus orca is Data Deficient, with the following statement: ‘The taxonomy of this genus is clearly in need of review, and it is likely that Orcinus orca will be split into a number of different species or at least subspecies over the next few years.’ This means that some orca types may be a different species and therefore each needs a separate conservation status.

    Besides the orcas being hunted down and captured for breeding or entertainment purposes, orcas are also actively hunted and killed by fisherman to reduce competition for fish. Moreover, orcas are also targeted by whaling. Whaling is the hunting of whales for their usable products such as their blubber, meat or skin.

    Today, commercial hunting of whales is banned, however some countries such as Greenland permit small hunts. Other threats to orcas include pollution from marine debris such as plastics, entanglement in discarded fish nets, oil spills and lack of food caused by overfishing or habitat loss. Recalling that orcas are at the top of the food chain, they are also indirectly affected if they consume prey that had, for example, indigested microplastics, or been exposed to contaminants such as sewage or pesticides. These harmful substances can accumulate in an orcas’ bodies and affect their reproductive and immune systems.

    What can you do to protect and conserve these magnificent animals?

    1. Support responsible tourism: choose responsible whale watching operators that adhere to guidelines for minimising disturbance to orcas and their habitats.
    2. Reduce plastic pollution: reduce use of single-use plastics, such as bags, bottles and straws to prevent pollution in marine environments.
    3. Support conservation organisations: if you are able to, consider donating to reputable conservation organisations dedicated to protecting orcas and their habitats.
    4. Educate others: spread awareness about the fascinating creatures that are orcas.
    5. Choose sustainable seafood: support sustainable fishing practices by choosing seafood that is caught or farmed using environmentally friendly methods.
    6. Avoid orca shows: refrain from attending marine parks, aquariums, or other venues that feature orcas as entertainment attractions.

    Relatives

    Orcinus orca is the only living species in the genus Orcinus. O. paleorca and O. citoniensis are extinct.

    Scientific name and classification

    Kingdom: Animalia
    Phylum: Chordata
    Class: Mammalia
    Order: Artiodactyla
    Family: Delphinidae
    Genus: Orcinus
    Species: O. orca (Linnaeus, 1758)

    References and further reading

    • Ford, J.K., Ellis, G.M., Balcomb, K.C. 2011. Killer whales: the natural history and genealogy of Orcinus orca in British Columbia and Washington. UBC press 2011.
    • Lewis, C.T., Short, C. 1879. ‘orca’, in: A Latin Dictionary. Perseus Digital Library. Available from: Perseus Digital Library interface. Accessed 17 May 2024 .
    • Ridgway, S.H., Brownson, R.H., Van Alstyne, K.R., Hauser, R.A. 2019. Higher neuron densities in the cerebral cortex and larger cerebellums may limit dive times of delphinids compared to deep-diving toothed whales. PLoS One. 16 Dec 2019;14(12):e0226206.
    • Baird, R.W. 2002. Killer whales of the world: natural history and conservation. Voyageur Press.
    • Heyning, J.E., Dahlheim, M.E. 1988. Orcinus orca. Mammalian species 304: 1–9.
    • Olsen, K. 2006. Orcas on the edge. National Wildlife Federation, Reston. Available at: https://www.nwf.org/en/Magazines/National-Wildlife/2006/Orcas-on-the-Edge.
    • Heptner, V.G., editor. 1989. Mammals of the Soviet Union, Volume 2, Part 2, Carnivora (Hyenas and Cats). Brill.
    • SeaWorld. Killer whale adaptations [Internet]. Orlando: SeaWorld; c2024 [cited 2024 May 17]. Available from: https://seaworld.org/animals/all-about/killer-whale/adaptations/.
    • Dutfield, S. Orca guide: diet, how they hunt, and what they’re related to. [Internet] Discover Wildlife. Facts about orcas. Bristol: Discover Wildlife; c2024 [accessed 17 May 2024]. Available from: https://www.discoverwildlife.com/animal-facts/marine-animals/facts-about-orcas
    • Wikipedia contributors. Orca [Internet]. Wikipedia. Available from: https://en.wikipedia.org/wiki/Orca. Accessed May 2024.
    • National Wildlife Federation. Orca [Internet]. Reston: National Wildlife Federation; [accessed 17 May 2024]. Available from: https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Orca
    • Business Insider. 2020. Orca attacks have caused great white sharks to flee from Cape Town, experts say. Business Insider. 11 Nov 2020. Available from: https://www.businessinsider.com/orca-attacks-caused-great-white-sharks-flee-cape-town-experts-2020-11. Accessed 17 May 2024.
    • Carwardine, M. 2001. Killer whales. DK Publishing (Dorling Kindersley).
    • Whales.org. Orcas (also known as killer whales). Whales.org. Available from: https://uk.whales.org/whales-dolphins/facts-about-orcas/#:~:text=Orcas%20(also%20known%20as%20killer,found%20in%20every%20single%20ocean. Accessed 17 May 2024.
    • National Geographic. 2019. Orcas’ welfare in captivity. Mar. Available from: https://web.archive.org/web/20200606082028/https://www.nationalgeographic.com/animals/2019/03/orcas-captivity-welfare/. Accessed 17 May 2024.
    • Ward, E.J., Holmes, E.E., Balcomb, K.C. 2009. Quantifying the effects of prey abundance on killer whale reproduction. Journal of Applied Ecology 46(3): 632–40.
    • Killer Whales Wiki. Kalina. Available from: https://killerwhales.fandom.com/wiki/Kalina. Accessed 17 May 2024.
    • Francis, D., Hewlett, G., 2007. Operation Orca: Springer, Luna and the Struggle to Save West Coast Killer Whales. Harbour Publishing.
    • Wikipedia contributors. 2005. Tilikum (orca) [Internet]. Wikipedia. Available from: https://en.wikipedia.org/wiki/Tilikum_(orca).
    • International Union for Conservation of Nature (IUCN). Species factsheet: [Orcinus Orca]. IUCN Red List of Threatened Species. Available from: https://www.iucnredlist.org/species/15421/50368125. Accessed 17 May 2024.

    Featured pic: Thomas Lipke
    Author:     Maria J Paul
    E-mail: m.paul@sanbi.org.za

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