A study from Australia is the first to scientifically document blue whales' killings by orcas.
Orcas were observed devouring the nutrient-rich tongues of the giant blue whales.
"This is the biggest predation event on this planet," a marine scientist said.
However, the scientific community has long debated whether orcas can hunt blue whales, the largest animal on the planet.
The debate was finally settled in a report published in Marine Mammal Science in 2022.
Orcas can hunt and kill blue whales
The report documented the first recorded observations of a pod of orcas — also known as killer whales — attacking blue whales off the coast of Western Australia.
The attacks were recorded by marine scientists from Cetrec WA (Cetacean Research). The report includes details of how the killer whales swam inside the mouth of the enormous whales to eat their nutritionally rich tongue just before they died.
"Here we provide the first documentation of killer whales killing and eating blue whales: two individuals killed, 16 days apart in 2019, and a third in 2021," the researchers wrote in the paper. "Notably, the first whale taken appeared to be a healthy adult."
Researchers arrived at the first killing of a 72-foot-long blue whale to see large chunks of skin and blubber having been gouged from its body and with most of the dorsal fin having been bitten off.
It was followed by relentless attacks by the orcas, where three lined up against the blue whale and pushed it underwater, while two attacked its head.
The study explains that 50 orcas joined the pack for six hours to feed on the carcass. Hunting in large numbers like this is not all that uncommon for orcas. They have highly-developed methods of communication which enables them to orchestrate hunting tactics as well as imitate each other.
A few weeks later, the next attack occurred when a blue whale calf was targeted. Twenty-five orcas attacked the 40-foot-long animal.
The final attack recorded by the study was on a 45-foot-long blue whale, chased for 15 miles in a 90-minute hunt. Again, the orcas' hunting strategy was to push and ram the whale under the water while others attacked its head and tongue. A 50-strong pod devoured the remains of the kill.
Mother orcas are the lead aggressors
Previous studies had concluded that orca attacks had to be executed by the biggest killer whales — who are male and can grow to 30 feet in length — to be successful. But the new research documented that these killings were led by female orcas, with the study saying that the drive to feed their offspring could make them more aggressive.
"This is the biggest predation event on this planet: the biggest apex predator taking down the biggest prey," study coauthor Robert Pitman, a marine ecologist at Oregon State University's Marine Mammal Institute, told National Geographic. "We don't have dinosaurs anymore, so for me as a whale biologist and a zoologist. It's an amazing thing."
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