Back in the winter of 2022, a pod of orcas off the coast of Western Australia appeared to free a humpback whale from a rope twisted around its tail. Experts questioned whether the orcas actually meant to rescue the whale.
It is unclear why the orcas approached the humpback whale in the first place. Part of the interaction was captured on drone video footage by observers with Whale Watch Western Australia.
At first, they thought the orcas might attack the humpback since orcas have been seen to attack humpbacks before.
Orcas hunt in packs so they can take down prey that is bigger than themselves, but usually, they aim for humpback calves and yearlings instead of fully grown adults.
During attacks on whales, orcas will try to grab the whales' flippers, turn them over, and hold them underwater to drown them.
But somehow, this humpback whale managed to escape from the orcas alive and well. It was the first time an interaction between orcas and a humpback was observed in Bremer Bay, Australia, in the summertime. So, why didn't the orcas hunt and kill the whale?
"It could be that the orcas' summer diet is distinctly different and humpbacks are 'out of season' (it is well documented that they do feed on beaked whales here, which would be a different hunting and feeding operation, a different food)," said Erich Hoyt, a research fellow at the charity Whale and Dolphin Conservation.
"It could be simply that the orcas have just eaten or are in the middle of some other behavior or that the entanglement somehow put them off."
Orcas do have complex social structures and well-developed brain regions linked to empathy and emotion, but there was no way to tell for certain if they felt a sense of altruism for the whale or other creatures of the sea.
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Typically, humpbacks spend the summer months in the Southern Hemisphere. They feed on krill in Antarctica. Between June and August, humpbacks can be spotted off the Australian coast during their migration north to their breeding grounds in subtropical waters. Then, they can be seen again when they return south to Antarctica between September and November.
That's why it was such a surprise to witness a humpback whale in Bremer Bay at the time. The whale was in poor condition.
It was emaciated and covered in sea lice, which are parasites that feed on the skin and blood of whales and fish. A piece of rope was tangled around its tail.
Two male orcas swam up to the whale out of curiosity. The whale tried to defend itself by beating its pectoral fins and tail fluke against the water.
Suddenly, the matriarch of the orca pod made her way over with great big splashes. When the water settled, the whale was free from the rope.
Finally, the orcas swam away from the whale. They spent the rest of the day socializing. Overall, this incident highlights how complex interactions between marine mammals can be.