World's biggest mammal executes underwater rolls

Scientists have found that blue whales perform acrobatic 360-degree rolls to attack their prey from below.

Blue whales are able to gulp up to 100 tonnes of krill-filled water in less than 10 seconds. The mammals are known to lunge at their prey, taking both the krill and a large quantity of water into their mouth at once. The water is then squeezed out through baleen plates, and the krill that cannot pass through is swallowed.

An adult blue whale can eat up to 40 million krill in a day.

A team of US researchers tagged a group of blue whales off the coast of southern California, to understand how they manage to capture prey despite their huge size. Suction cups were attached with acoustic recording tags to track their movements.

The whales were found to execute underwater spins in order to access krill, using their flippers and flukes.

"At about 180 degrees, the mouth just begins to open so that the blue whale can engulf the krill patch from below," said Dr Jeremy Goldbogen, from the Cascadia Research Collective that conducted the research.

"As the blue whale engulfs the prey-laden water, it continues to roll in the same direction and completes a full 360 roll and becomes horizontal again ready to target and attack the next krill patch."

The largest animal ever known to have existed, the blue whale can grow up to 30 metres (98ft) long and can weigh 180 tonnes - proving that their hunting technique is quite an achievement. But the researchers believe the extra effort is rewarded with enormous meals.

The findings have been published in the Royal Society journal Biology Letters.