Orcas recorded killing and eating world’s largest animal, the blue whale, for the first time

The orcas teamed up to ram the whale's flank and force it underwater

It was previously thought that in order to take down a blue whale, male orcas had to actively participate. The recent attacks demonstrate that female-led efforts could be successful. Photo by Cetrec WA/YouTube

Gruesome details about how orcas hunt the world’s largest animal, the blue whale — like swimming inside their mouths to eat their tongues before they die — have been revealed in a recently published paper.

Orcas are known for their ability to hunt in pods, or groups, and work together to kill prey. There have been prior reports of orcas, also called killer whales, chasing blue whales; however, none of the attacks have been verified until now.

“This paper is the first to really confirm a blue whale kill and at the same time it provides firm confirmation that killer whales will even go after mature healthy blue whales,” Erich Hoyt, a research fellow at Whale and Dolphin Conservation, told The Guardian.

The findings of the paper are also crucial in understanding orca dynamics. It was previously thought that in order to take down a blue whale, male orcas had to actively participate. The recent attacks demonstrate that female-led efforts could be successful. And it was presumed to be a female orca, involved in all of the attacks, who first feasted on the whale’s tongue.

Three attacks since 2019 were recorded off the coast of Australia, in Bremer Bay, and were outlined in a report in Marine Mammal Science. The attacks were observed from commercial whale-watching vessels.

About a dozen orcas were witnessed attacking a blue whale, estimated to be 18 to 22 metres long, on the morning of March 21, 2019. Chunks of blubber and skin, as well as most of its dorsal fin, had been bitten off, leaving “underlying bone exposed.”

After about 20 minutes, observers noticed the whale slowed and started swimming in circles. It was “bleeding profusely” and growing weaker.

The orcas teamed up to ram its flank and force it underwater.

“While it was still alive,” the paper explained, “an adult female killer whale put its head inside the blue whale’s mouth and began feeding on its tongue.”

When the whale finally started to sink, a sign of its death, a total of around 50 orcas joined to feed on the fresh kill.

Orcas killed a blue whale calf in a second attack observed at noon on April 6, 2019. The orcas were seen taking turns striking in groups of five or six, while around 10 to 15 orcas remained on the periphery. When the calf tried to dive, they pushed it to the surface. But when it tried to breathe at the surface, the orcas “swam up on its head and blowhole.”

Like the attack in March, an adult female orca put her head into the blue whale’s mouth and fed on its tongue.

The carcass was submerged around 45 minutes later. Again, the group reached around 50 orcas who continued to dive and feed on the kill for several hours.

The third attack was recorded on March 16, 2021. A dozen orcas pursued a blue whale, believed to be a yearling, for 25 km in a chase that lasted 97 minutes.

The blue whale is an endangered species that can weigh up to 200 tons (that’s the weight of 33 elephants) and has a heart the size of a Volkswagon Beetle, according to World Wildlife Fund. There are about 10,000 to 25,000 left in the wild.

Although orcas have been observed feeding on large whales, Hoyt told The Guardian that the ones in South Australia had an “unusually diverse diet.”

“This is strange because elsewhere in the world,” he said, “killer whales are fussy eaters and tend to learn from their pod how to catch food, and what is food, and they stay with that, whether it’s salmon around Vancouver Island or sea lion pups at Punta Norte in southern Argentina.”

The paper cites orca predation as a “potential impediment” for other species to recover, like the western grey whale or bowhead whale.

“It remains to be seen how much of an impact it could have on blue whale recovery in Australia, and elsewhere, as populations of large whales continue to recover from commercial whaling,” it concludes.