Orcas have been recorded hunting and eating blue whales

Orcas have been recorded hunting and eating the world’s largest animal — the blue whale.

An Australian team stumbled across the phenomenon during an annual survey off the Perth coast.

Orcas or killer whales are toothed animals belonging to the oceanic dolphin family.

It is the first time the gruesome attacks have been recorded, shedding fresh light on marine ecosystems. The killer whales teamed up to ram the beast’s flank, forcing it underwater, say scientists.

‘When we arrived about 14 killer whales were attacking the blue in 70-metre waters, with the female killer whales leading the attack,’ said Isabella Reeves, a PhD student at Flinders University, Adelaide.

‘At arrival we already noticed a substantial flesh wound on the top of its head with bone exposed,’

‘The dorsal fin was missing, no doubt bitten off by the killer whales. Tooth-rake marks were evident in front and behind where the dorsal once was and even all the way to the whale’s tail,’ she added.

The orcas even swam inside their giant prey’s mouths — eating their tongues before they die.

Blue whales are the largest creatures to have ever existed on earth, with females being bigger than males. They can reach up to 110 feet in length and weigh 200 tons — as many as 33 elephants. Their heart is the size of a Volkswagen Beetle, according to World Wildlife Fund.

There are only about 10,000 to 25,000 blue whales left in the wild. This discovery could help save the endangered species.

‘Soon after, there was large chunks of skin and blubber stripped off the sides of the whale. The blue was bleeding profusely and was weakening, evident by its slow speed,’ said John Totterdell, lead author of the study.

‘Coordinated attack by several killer whales resulted in some females ramming the side of the whale while others attacked the head,’ he explained. ‘Close to the end, a female animal lunged headfirst into the blue’s mouth, presumably to feed on the tongue. The whale weakened more and we did not see the carcass again,’

After the whale carcass had sunk, about 50 killer whales were reportedly sighted in the area feasting on the blue whale’s flesh.

The chaos also attracted flesh-footed shearwaters, albatross, storm petrels and groups of more than 100 long-finned pilot whales.

The grisly event described in Marine Mammal Science happened nearly three years ago. Just two weeks later a blue whale calf was hunted down by many of the same Orcas. A similar incident occurred last year.

Orcas are the ocean’s apex predator — mainly feeding on fish, squid, seals, sea birds. They are much smaller than blue whales, reaching up to 30 feet in length and weighing over six tons.

Until now, it was thought they only ate whale calves of much smaller species – such as grays and humpbacks. Understanding their role in the food chain is vital for monitoring their prey — including those still recovering from commercial whaling.

In Australia, two populations of killer whales have recently been discovered – and both feed at least in part on marine mammals.

One, found off the west coast, has over 140 known animals to date, roaming the waters mostly during summer and autumn.

‘These guys are ferocious with a preference for squid, fish and beaked whales. In recent years recordings of the number of beaked whales taken have increased, in this region they are known to also predate on humpback and minke,’ said Totterdell.

Killer whales attacking and harassing blue whales have previously been documented but the three attacks are the first confirmed kills.

The unique hunting strategy, if successful, results in tiring out and immobilising the blue whale, leaving it defenceless and an easy target.

Researches believe that being hunted by killer whales, has slowed down the gray whale population recovery in the Northwest pacific.

This study, combined with recent research, highlights the need for an increased understanding of killer whale population ecology so scientists can better determine their impact on the marine ecosystem in Australian waters.

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