In an hours-long struggle, as many as 70 killer whales hunted down and killed a blue whale off the southwestern coast of Australia, according to a marine biologist who saw the “astonishing, a little bit disturbing and truly mind blowing” event take place.
At first, it seemed like a normal day of whale watching, said Kristy Brown, a marine biologist with Naturaliste Charters, a company that runs whale-watching tours in Western Australia. The vessel happened upon two pods of orcas in Bremer Bay Canyon, about 28 miles (45 kilometers) off the coast, that were “playing and surfing the waves,” Brown wrote in a March 16 blog post.
But soon, people on the boat noticed that the orcas were creating nonuniform wave surges. This was odd; when orcas hunt beaked whales, for instance, they tend to move in unison, creating waves surging in one direction. “But this was different, these surges were scattered,” Brown said. Then, around 11:30 a.m. local time, there arose “a long, high blow [spray] that stayed in the air … It was a blue whale, estimated to be 16 meters [52 feet] long, with plenty of years left to live.”
It’s unclear whether the prey was a juvenile blue whale (Balaenoptera musculus) or a pygmy blue whale (Balaenoptera musculus brevicauda), as “both use these waters,” Brown told Live Science in an email. Regardless, the blue beast made a big mistake when it ventured alone into the canyon system, where orcas swim.
Despite their name, orcas (Orcinus orca), which are also called killer whales, are not whales. Rather, they’re the largest species of the dolphin family, according to the Ocean Conservancy. And, like their “killer” name suggests, these marine mammals are known for hunting all kinds of prey, including humpback whales, seals, sea turtles and even great white sharks.
In this case, even though the blue whale was nearly twice the length of the largest orca, which can grow to lengths of about 31 feet (9.5 m), it couldn’t shake off its pursuers. “It was completely surrounded by orca[s] as it swam,” Brown wrote in the blog. Moreover, the orcas didn’t appear to rush the hunt, but instead were “strategic, thoughtful, collaborative, patient [and] persistent,” Brown wrote in the blog.
In cyclical waves, “multiple orcas were on the animal, jostling with it and swimming fast, beside and under it, whilst others dropped off the chase to rest in our wake and cruise along and beside the hunt, easily 200 m [656 feet] back,” she said. It seemed that “tiring out the blue was their goal,” she noted.