Biologists have published the first observations of orcas hunting and eating an adult blue whale, the largest animal ever to have existed.
Flinders University biologist Isabella Reeves was among those who witnessed the event from a research boat off south-west Australia.
“It was pouring down with rain, there was lightning in the background. I was at the point where I was starting to feel seasick when we stumbled across it,” she says. “I forgot all about my seasickness. We just had to gather as much data as we could.”
The observations are presented in all their grisly detail in the journal Marine Mammal Science. The attack involved about 14 orcas and was led by the adult females. The blue whale was estimated to be 18-22m long and was apparently healthy.
After it had died and sunk to the seabed, about 50 orcas were seen bringing lumps of flesh to the surface and sharing them. The team has since witnessed the same group hunting two blue whale calves.
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Killer whales attack and kill blue whale. © Cetrec WA
Orcas are skilled hunters and will operate as a group to take down large prey, such as minke whales, humpback calves and even great white sharks, but it remains to be seen how common blue whale-hunting is.
“If you can, why wouldn’t you take the world’s biggest animal? It’s a good way to feed your family,” says Reeves. “It’s unlikely that they only do it when we are there.” She speculates that such events may become more frequent as blue whales recover with the decline in whaling.
Main image: Orcas killing a blue whale. © John Daw on board Naturaliste Charters