Are Orcas Dolphins or Whales?

Orca, also known as killer whales, are often considered whales due to their large size. But biologically speaking, orcas are actually a dolphin species – specifically, the largest dolphin species!

In this article, I will discuss everything in detail about why orcas are dolphins and what makes them different. So, read the whole article to discover more about orcas.

Are Orcas Dolphins or Whales?

Based on their biological classification and ancestry, orcas are actually dolphins. Despite their large size and fierce predator status, these marine mammals are the largest members of the Delphinidae family, which is also known as the oceanic dolphin family.


While there is some debate around whether orcas should be considered whales due to their size – with some individuals and organizations referring to them as such – the scientific community largely agrees that taxonomically speaking, orcas fall under the category of dolphins.

Furthermore, genetic research shows that orcas share a common ancestor with other dolphin species, such as the Pacific white-sided dolphin and the common bottlenose dolphin. This further supports their classification within the dolphin family.

Interestingly, orcas are also unique within the dolphin family due to their diverse diet, which includes fish, squid, and even other marine mammals such as seals, sea lions, and other whale species. This contrasts with most other dolphin species that primarily feed on fish.

Why Is Orca Believed to Be a Whale?

Orcas are mistakenly believed to be whales by many people. However, despite its name, the Orca is not a whale but a dolphin. Below are some reasons why Orca is believed to be a whale:


Massive size

The Orca is the largest species in the dolphin family. Adult orcas can grow up to 9.5 meters in length and weigh up to 6,800 kilograms. This size is comparable to some species of whales, such as the pygmy sperm whale and the dwarf sperm whale. Therefore, people often mistake orcas for whales due to their impressive size.

Common name

The common name for orcas is the “killer whale”, which also contributes to the belief that they are whales. The name “whale” is a part of their common name. Unlike other dolphins, orcas have a fierce, predatory reputation and have been known to hunt larger marine mammals, such as seals, sea lions, and whales. This reinforces the misconception that orcas are whales.

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Orcas have a distinctive black-and-white colouration, which also adds to their similarity to some whale species. Some whales, such as the beluga and killer whales, also have a similar pattern, but orcas have a more robust and muscular body structure than other dolphins, making them more similar to whales.


Similar to some species of whales, orcas are highly social and live in groups called pods. Orcas have complex vocalizations and communication systems used to help them hunt and socialize with each other.

They also have a unique culture, with different pods having distinctive dialects, hunting techniques, and social behaviours. These similarities to some whale species could contribute to the belief that they are whales.

Why Is Orca Called a Killer Whale?

The Orca, also known as the killer whale, earned its name from the ancient sailors who observed them hunting and preying on larger whale species. Initially, they referred to these majestic creatures as ballena asesina, meaning ‘whale killer,’ a term that was eventually adapted into the more straightforward ‘killer whale.’

Orcas have a diverse diet that ranges from fish and squid to seals, sea lions, and even large whales. As apex predators, they are known for their exceptional hunting skills and coordinated teamwork when hunting prey.


Their hunting methods involve strategic planning and execution, often using their powerful tails to stun and kill prey. Additionally, orcas work in groups, with one Orca leading the hunt while the others help corral and tire the prey.

Despite being referred to as ‘killer whales,’ there have been very few documented instances of orcas attacking humans in the wild. These animals are typically non-aggressive toward humans and have even been known to display curious and playful behaviour in the presence of humans.

Why Is Orca a Dolphin, Not a Whale?

Despite their reputation as “killer whales,” orcas are actually members of the dolphin family Delphinidae, making them anatomically and biologically more similar to common dolphins than to whales.

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One of the key distinctions between dolphins and whales is overall size. While some dolphin species can grow quite large (such as the pilot whale, which can reach nearly 25 feet in length), orcas are the largest members of the Delphinidae family and can reach lengths of up to 32 feet.


However, size alone is insufficient to classify an animal as a whale. Taxonomy, or the science of classifying living organisms, considers a range of physical, genetic, and behavioural characteristics when assigning species to different families and groups. When all of these factors are considered, it becomes clear that orcas are most closely related to other dolphin family members.

A few other key biological and anatomical features help distinguish orcas from dolphins. One of these is their teeth – unlike most whales, which have baleen instead of teeth, orcas have a row of large, conical teeth that they use to hunt and capture prey.

They are also highly social animals and live in complex family groups (known as pods) with sophisticated communication systems.

Overall, while the size of orcas may lead some people to think of them as whales, they are definitively classified as members of the dolphin family based on a range of biological and anatomical factors.

Are Orcas Friendly to Dolphins?

Orcas are not necessarily friendly to dolphins. While there are instances of Pacific white-sided dolphins playing near orcas, killer whales are known to be the only predators that regularly kill and devour these dolphins. Orcas are apex predators, meaning they are at the top of the food chain in the ocean and eat almost everything, including dolphins.

Orcas have different types of diets depending on their region and specific pod. For example, some orcas mainly eat fish, while others target marine mammals like seals, sea lions, and dolphins. However, even those orcas that primarily eat fish have been known to hunt and kill dolphins.

Orcas and dolphins interact in various ways, such as playing together or swimming in mixed pods. However, these interactions do not necessarily indicate friendly behaviour, as orcas could be playing with dolphins as a form of practice for hunting.

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Additionally, interactions between orcas and dolphins can turn violent, with orcas attacking and killing the smaller dolphins.

Are Orcas Friendly to Whales?

Orcas as “killer whales” and their known hunting habits, it is easy to assume that orcas are not typically friendly towards whales. While orcas have been known to attack and feed on several species of marine life, including fish and seals, they also take down much larger prey, such as whales.


In fact, according to a recent news report from CNN, a group of about 30 orcas attacked two grey adult whales off the coast of California, injuring both but ultimately allowing them to escape. This incident supports the idea that orcas are not friendly towards whales, as the orcas clearly saw these larger animals as potential prey and attempted to hunt them.

However, there may be some exceptions to this generalization. There have been isolated reports of orcas exhibiting what appear to be friendly behaviours towards other marine animals, including whales. For example, there have been sightings of orcas playing and interacting with grey whales in the wild.

Still, such instances are relatively rare, and the overall evidence suggests that orcas are not typically friendly towards whales. Instead, they are powerful and skilled hunters capable of taking down some of the largest animals in the ocean – including the very same ones that they share a name with.


I hope you now understand that orcas are actually dolphins. Although they may be compared to toothed whales, in terms of anatomy and behaviour, they are more similar to other dolphins. Even though they are referred to as “killer whales,” orcas have been known to display curious and playful behaviour in the presence of humans.

Regarding their relationship with other marine life, including dolphins and whales, orcas tend to treat them as prey rather than friends. However, there have been rare instances where orcas have interacted peacefully with whales, suggesting that they might be capable of exhibiting friendly behaviour under certain circumstances.

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