Species Spotlight: Orca

Orcas, also known as killer whales, are one of the most recognized and misunderstood marine mammals in the ocean. Phylogenetically, they are the only living species in the genus Orcinus, which are placed within the dolphin family (Delphinidae) and their scientific name being Orcinus orca (Ford et al.). Unlike baleen whales, which filter small organisms through specialized comb-like plates, orcas are part of a group called toothed whales. This means that, similar to dolphins and porpoises, orcas have teeth that help them catch bigger prey, such as fish and sea lions (Castro et al, 2024). The name “killer whale” has a long and misunderstood history where early sailors reportedly saw orcas hunting large whales and called them “whale killers,” but like the game ‘telephone’, the phrase eventually shifted to “killer whale” (Ford et al.). These marine mammals live in oceans all around the world, from the Arctic and Antarctic to tropical seas, and they are highly adapted to various marine environments (Ford et al.). 

Comparison of the mouth structures of a toothed whale (orca) and a baleen whale, highlighting the difference between teeth and baleen plates. Orca photo credit: Flickr – toofarnorth. Baleen photo credit: Hakai Magazine

Orcas have many adaptations that make them suitable for ocean life. Their black and white coloration acts as a camouflage technique called countershading. This allows orcas to blend in with their surroundings, with the white underside blending in from below and the black back blending in from above (Ford et al.). They rely on echolocation, using clicking noises and listening for the echoes to understand their surroundings (Ford et al.). Orcas are also known for their strong family bonds. Mothers give birth to a single calf after a 15–18 month pregnancy, and the calves often remain with their pods for life (Ford et al.).

A closer look at how countershading benefits species in these habitats. Photo credit: Facebook

Killer whales’ intelligence, complex behavior, and position toward the top of the food web make them an important species to understanding ocean ecosystems. Although their common name may suggest violence, killer whales are thoughtful and skilled predators. As apex predators (animals at the top of the food web), orcas play a vital role in marine ecosystems. Their diet can include fish such as salmon, rays, sharks, seals, dolphins, and even large whales (Ford et al.). They hunt in pods using coordinated strategies and often pass these techniques down through generations. Calves learn from their elders, often through observation and imitation, much like primates do (Ford et al.).

Orca pods serve as far more than hunting groups; they are complex and highly organized social communities. Orcas have unique vocalizations that differ between pods, almost like regional dialects in humans, and their groups are led by the oldest female (Ford et al.). This social complexity is so advanced that some scientists compare their social structures to those of chimpanzees and humans (Dunbar et al., 2025). Their intelligence and emotional depth are shown in the way they communicate, care for young, and mourn their dead. For instance, Tahlequah, a female Southern Resident orca, carried her deceased calf for 17 days, a poignant display of the species’ deep emotional bonds (Watson, 2016).

A pod of Southern Resident killer whales staying together while traveling. Photo credit: Orca Conservancy 

Despite their strength and intelligence, wild orcas face serious challenges. Southern Resident killer whales, found off the coast of the Pacific Northwest, have been especially affected by the decline of Chinook salmon (Oncorhynchus tshawytscha), which is their primary food source (Block, 2018). These salmon populations have decreased due to dam construction, habitat degradation, and overfishing. As a result, orcas are experiencing nutritional stress, reproductive failure, and reduced survival rates (Block, 2018).

Orcas have also been portrayed negatively in the media, which has influenced how the public views them. The documentary Blackfish (2013) brought global attention to the mistreatment of orcas in captivity, particularly the psychological and physical effects of confining such large, social animals in marine parks like Sea World for human entertainment (Anderson et al., 2016). It highlighted how captivity of wild animals disrupts natural behaviors and leads to increased aggression, even in orcas with no known history of harming humans in the wild (Anderson et al., 2016).

In the Pacific Northwest, efforts to help orcas adapt to these changes have focused on increasing salmon availability. This includes restoring rivers and removing outdated dams to allow salmon to reach their spawning grounds (Block, 2018). Because orcas are a keystone species (species with a disproportionately large impact on their environment relative to their abundance) their decline signals wider ecosystem problems. Without them, mesopredators such as seals and sea lions can increase in number, depleting fish populations and destabilizing the balance of the marine ecosystem (Saligumba, 2025). Helping orca populations recover benefits not only orcas but the entire marine food web.

In addition to struggling with limited food sources, orcas are also threatened by pollution, boat traffic, and underwater noise. These human-made stressors can interfere with their ability to hunt, navigate, and communicate with one another (Ford et al). To track how orcas are coping with these challenges, researchers use tools like satellite tracking, acoustic monitoring, and photo identification (Ford et al).

Two scientists taking samples of a 15 ft juvenile orca found on the Norfold coast. Photo from First stranded Orca found in almost 20 years in the Wash, 2020. 

Orcas are especially vulnerable to pollutants because of their position at the top of the food web. Toxins like PCBs (polychlorinated biphenyls) or other human-made chemicals and microplastics accumulate in the bodies of prey and eventually become concentrated in predators, a process known as bioaccumulation. This can affect orca immune systems, reproduction, and overall health. One example of bioaccumulation occurred in 2020, when a young orca stranded in England was found with a large piece of plastic in its stomach. Although it wasn’t the direct cause of death, the discovery highlighted growing concerns about how marine pollution is affecting top predators like orcas (Horton, 2020).

Some researchers believe that different orca populations may actually be separate species or subspecies, a distinction that could impact how they’re classified and protected in the future (Ford et al). One group, the Southern Resident killer whales, is already listed as endangered in the U.S. and Canada due to their small population size and limited access to food (Ford et al). Globally, orcas are listed as “Data Deficient” by the International Union for Conservation of Nature (IUCN), meaning there isn’t enough data to fully evaluate their conservation status (Ford et al). Still, the threats they face, especially those driven by human activity, are well documented and increasingly urgent.

The trend in population size of the Southern Resident killer whale from data taken between 1973-2001 showing an almost doubled decline. Figure taken from Status Review of Southern Resident Killer Whales (Orcinus orca) under the Endangered Species Act 2002. 

So, what can we do to help? Supporting sustainable fisheries and reducing our use of single-use plastics are great first steps. We can also advocate for stronger noise pollution laws and support policies that aim to help ocean habitats. Choosing not to visit marine parks that keep orcas in captivity and instead, supporting ethical conservation organizations can make a meaningful impact. Local organizations like OC Habitats contribute by educating communities about marine life and work to help protect coastal ecosystems, which play an important role in supporting the broader food web that orcas rely on. While they may be called “killer whales,” orcas are not the villains we commonly hear about. They are intelligent, social, and vital to ocean health. By staying informed, making mindful choices, and supporting conservation efforts, we each have the power to protect orcas and the oceans they call home.

Want to learn more? Here are some related OC Habitat blogs:

Endangered Orcas Held Captive by the Entertainment Industry By Ellis Waterman

Species Spotlight: Minke Whales by Beverly Alvarez 

Marine Mammal Protection Act by Sanjay Das

Species Spotlight: Vaquita by Christina Robinson

Species Spotlight: Beluga by Joyce Vu

References:

• Anderson, R.; Waayers, R.; Knight, A. Orca behavior and subsequent aggression associated with oceanarium confinement. Animals 2016, 6, 49. 

• Block, K. Save the orcas of Puget Sound. Humane World for Animals 2018. 

• Castro, P.; Huber, M. E.; Ober, W. C.; Ober, C. E. Marine Biology; McGraw Hill, LLC:

  New York, NY, 2024. 

• Dunbar, R. I. M.; Shultz, S. Insectivorans and carnivorans exhibit the same social brain

  relationship as primates. Biorxiv 2025. 

• Horton, H. First Orca found washed up on coast of Britain in 20 years as scientists say it

  had plastic in its stomach. https://www.telegraph.co.uk/news/2020/01/14/first-orca-found-washed-coast-britain-20-years-scientists-say/

• John Ford (The University of British Columbia, D. of Z.; Randall Reeves (IUCN SSC

  Cetacean Specialist Group); Robert Pitman (Protected Resources Division, S. F.

• S. C. The IUCN Red List of Threatened Species. https://www.iucnredlist.org/species/15421/50368125.

• Krahn, M. M.; Wade, P. R.; Kalinowski, S. T.; Dahlheim, M. E.; Taylor, B. L.; Hanson, M. B.; Ylitalo, G. M.; Angliss, R. P.; Stein, J. E.; Waples, R. S. Status Review of

• Southern Resident Killer Whales (Orcinus orca) under the Endangered Species Act 2002. 

• Saligumba, M. F. Apex predators: Orcas in marine ecosystems – and what happens

  when they disappear. Discover Wild Science 2025. 

• Watson, T. Orca Whales Mourn Their Dead, Just Like Us. National Geographic 2016.