Teamwork and coordination are essential in a killer whale hunt.

In the second event, the study described five to six killer whales that were actively engaged in the attack on the blue calf at all times, while another 10 to 15 lingered on the periphery, all roles rotating frequently.

A group of killer whales during the first attack hunt and feed on an adult blue whale.Credit:CETREC WA & ORCA Project

During the third attack, a minimum of 20 killer whales were involved at the same time.

“There was no bite or fatal blow,” Mr Totterdell said. “[Instead]what they do with these big animals is just wear them out [and] inhibit their movement. They come under that; they don’t let him dive.

Researcher and PhD student Isabella Reeves, who studies evolutionary ecology, said killer whales can be “opportunistic” and have learned strategic behaviors from females in their families.

“[Killer whales] have matrilineal societies, which means they basically travel in those female-led groups. Very often, the grandmother directs these [kills]“said Ms. Reeves.

The study showed that each of the attacks was localized further north in the Bremer sub-basin and canyons where killer whales often preside.

“For killer whales, shallow water is best, so once they’ve killed the animal, especially one that’s big, it can just sink and they can just dive in and grab bits. [of it].”

While this is believed to be the first time humans have seen and documented killer whales successfully attacking and killing a blue whale, it may not be the first time this has happened.

“That may well indicate that before commercial whaling this was normal. That’s what the killer whales did,” Mr Totterdell said.

Now that blue whale numbers are steadily increasing, it’s possible killer whales are returning to an old food source.

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