Are killer whales dolphins? Yes. Orcas, as killer whales are also known, are the largest members of the oceanic dolphin family, the same family as the bottlenose dolphins you might spot off the beach. They’re whales only in the broad sense that all dolphins are a kind of whale. In reality, they’re far more closely related to dolphins than to humpbacks or blue whales.
How whales and dolphins are related
It helps to know how the family tree works. All whales, dolphins and porpoises belong to a group called cetaceans, and that group splits into two main branches.
Baleen whales, such as humpbacks and blue whales, have no teeth. They filter tiny prey from the water through comb-like plates called baleen, as I explain in why are whales so big? Toothed whales, on the other hand, hunt larger prey. They include sperm whales, belugas, porpoises and every dolphin.
Within the toothed whales, orcas belong to the oceanic dolphin family, Delphinidae, and they’re its biggest members. Large males can weigh around six tonnes, according to Wikipedia’s orca article. So a dolphin is technically a small toothed whale, and an orca is the biggest dolphin of all.
Like other toothed whales, orcas find prey by echolocation: they send out clicks and listen for the echoes, a skill I look at in what is echolocation? It isn’t unique to dolphins. Sperm whales, porpoises and other toothed whales do it too.
Orca or killer whale: why two names?
There’s no difference between them. “Orca” and “killer whale” are simply two names for the same animal.
The “killer” part has a long history. Orcas are top predators that hunt seals, fish, sharks and even other whales. Early sailors who watched them attack large whales called them “whale killers”, asesina ballenas in Spanish, and over time the phrase flipped into “killer whale”.
Many people now prefer “orca”, from the scientific name Orcinus orca. That’s partly because “killer” is a bit unfair: there are no confirmed cases of a wild orca killing a person.
The killers of Eden
In Twofold Bay, near Eden on the far south coast of New South Wales, a pod of orcas hunted alongside people for generations. It was a partnership with few parallels anywhere in the world.
It began with the Thaua people, part of the Yuin nation, who saw the orcas as kin; a Thaua person who died was believed to be reincarnated as a killer whale. From around the 1840s, commercial whalers, including the Davidson family’s whaling station, joined in and employed many skilled Thaua whalers.
When the orcas found a baleen whale, they would herd it into the bay, and some would slap their tails near the station to alert the whalers. After the kill, the orcas were rewarded with their favourite part, the tongue, while the people took the rest. That arrangement became known as the “Law of the Tongue”, as the researchers behind a 2023 study explained in an article for The Conversation, republished by Down To Earth.
The most famous orca was Old Tom. He joined the hunts for decades, and he was found dead in the bay on 17 September 1930, according to Wikipedia. His skeleton is still on display at the Eden Killer Whale Museum.
In 2023, a team led by Isabella Reeves of Flinders University drilled into one of his teeth and sequenced his DNA. As Flinders University reported, he was most similar to modern New Zealand killer whales, but most of his DNA isn’t found in any living population. The researchers now suspect the Eden pod is extinct.
In recognition of the orcas’ importance to the Thaua people, the nearby Ben Boyd National Park has been renamed Beowa National Park. Beowa is the Thaua word for killer whale.
Where to see orcas in Australia
Today, the best place in Australia to see orcas is Bremer Bay, on the south coast of Western Australia. Every year, from about January to April, orcas gather around a group of undersea canyons about 70 km offshore, and tour operator Naturaliste Charters has identified more than 275 regular animals there over the years.
Why there? Flinders University oceanographer Jochen Kämpf found that the head of one canyon in particular, the Hood Canyon, funnels nutrient-rich particles up from the deep, feeding a local food web, as Flinders University explains.
Orcas also turn up off the east coast now and then during the winter humpback migration, following the whales they occasionally hunt.
Dolphins with a big reputation
So killer whales are dolphins, the biggest of their family, with a name that owes more to old sailors’ stories than to biology. They’re intelligent, social and astonishingly adaptable hunters. And in one corner of New South Wales, they were partners.
Their baleen-whale cousins went in a very different direction, which is the story behind why are whales so big? And for how orcas find their prey by sound alone, see what is echolocation?
Sources
- Wikipedia: Orca
- The Conversation, via Down To Earth: For generations, killer whales and First Nations hunted whales together
- Wikipedia: Old Tom (orca)
- Flinders University: Evolutionary secrets of Old Tom and the killer whales of Eden (2023)
- Flinders University: Clues to killer whale cluster (2021)