Getting to Know Orca Ecotypes: The Ocean’s Apex Predator

A species that have always fascinated me are orcas, the ocean’s apex predator. Often referred to as Killer Whales, this name isn’t, strictly speaking, true of the species. Believed to have been lost in translation Killer Whales were originally called Whale Killers as some ecotypes (I’ll explain more about them later) hunt and kill some whale species as prey. And while they are technically a whale - they are actually the largest species of dolphin. There are many misconceptions about this incredible species so let's learn a bit more about them. 

Orcas can be found all across the world from the arctic to Antarctica, most commonly in colder water. Despite orcas all having their characteristic black and white markings and striking dorsal fin, they are all adapted differently to suit which region they live in. These adaptations are where we get the different orca ecotypes. 

So what are ecotypes? 

Ecotypes simply refer to the different types within a species a bit like different breeds of dog. Living in different ecosystems around the world, orcas have adapted not only their appearance but hunting technique, prey preference and even communication to allow them to be better adapted to their environment. 

It is currently unclear exactly when the divergence of orcas began, however a study looking at the genomic data from killer whale ecotypes, suggests that it was at least 250,000 years ago. While other studies found data suggesting it was much earlier than this between 350,000 and 700,000 years ago. With research still continuing to uncover new information about different orca populations it's hard to put a definitive figure on how many orca ecotypes there are but the current figure stands at 10 but in reality is likely to be higher.

The different orca ecotypes: 

• Resident Orcas

There are two types of resident orcas, southern residents which are made up of three separate pods (J,K and L) and northern residents which have around 16 pods. Within the pods there are several family subgroups all following the matriarchal system common with all orcas types. Each pod has their own unique traits and are genetically and acoustically distinct from other groups. Resident Orcas feed exclusively on fish and live in relatively small areas around large fish populations. Their preferences depend on their location but research has suggested that salmon is commonly a favourite. They will tend to hunt alone but have been found to share their prey within their families - particularly the females. 

• Bigg’s (Transient) Orcas 

Named after whale Researcher Dr. Michael Bigg, the Bigg’s or Transient orcas, as their name suggests, showed transient/nomadic behavioural tendencies. What was once a relatively elusive species numbers of transient orcas are on the up, this is believed to be as a result improved food sources. Unlike resident orcas the Bigg’s orca feeds solely on marine mammals such as seals, sea lions, dolphins and porpoises.Transients are less vocal due to this difference in diet, allowing them to hunt prey without being heard - often communicating again after a successful hunt.  

• Offshore Orcas

Little is known about the offshore orcas, living far from land these elusive whales are rarely seen. Although still unclear exactly what their diet consists of, their teeth suggest they are eating things with rough skin such as sharks due to how worn down they are. They have also been seen to feed on fish as well. 

• North Atlantic Type 1

North Atlantic Type 1 orcas are widely distributed throughout the North Atlantic Ocean, especially around Norway, Iceland, and the British Isles. These orcas are generalist feeders, known to consume a variety of prey including herring, mackerel, and sometimes marine mammals. They often exhibit complex hunting techniques, such as carousel feeding, where they herd fish into tight balls (bait balls) before stunning them with tail slaps. Type 1 orcas tend to have more worn teeth due to their fish-based diet causing their scales to have a sandpaper like effect on the orcas’ teeth. Their physical appearance includes a relatively short, rounded dorsal fin and a medium-sized eye patch that is angled slightly forward.

• North Atlantic Type 2 

In contrast, North Atlantic Type 2 orcas are less commonly encountered and tend to be found in deeper, offshore waters, due to this less is known about them and their population structure. These orcas are believed to specialise in hunting marine mammals such as other whales and dolphins. Their diet leads to distinctive tooth wear patterns, often showing minimal wear compared to Type 1 orcas, due to the softer nature of mammalian prey. Physically, they are usually larger than Type 1 orcas and exhibit a more prominent, upright dorsal fin. Their eye patches are generally larger and more horizontally oriented. 

• Antarctic Type A

Antarctic Type A orcas are the largest and most widely roaming of the known Antarctic orca ecotypes. They are typically found in open water areas rather than near the pack ice and are known for preying primarily on minke whales, though they may also hunt other large marine mammals. These orcas are characterised by their tall, straight dorsal fins and large, elliptical eye patches that are set far from the eye. Their coloration is starkly contrasting, with a clean black-and-white pattern. Type A orcas are highly social and often travel in groups, exhibiting coordinated and strategic hunting behaviours. Their wide-ranging movements across the Southern Ocean reflect their adaptability and predatory prowess in vast, open marine environments.

The Orca Story Isn’t Finished Yet

So, while this covers the main known ecotypes at the time of writing, ongoing research continues to reveal just how complex orcas really are. Some scientists now believe there may be more than six distinct ecotypes, each with unique behaviours, appearances, and diets. Exactly how many groups there are might still be unclear, but one thing is certain - orcas remain one of the most intelligent, adaptable, and formidable predators in the ocean. It makes you wonder, if we’ve only scratched the surface with orcas, what else lies beneath the waves?

If you enjoyed reading this, whether you want to collab or simply just talk all things ocean get in touch!