Deep down, blue whales go to the right

Scientists have discovered that blue whales have leftist tendencies — but only on the surface.

Blue whales are lefties on the surface, but deep down they roll to the right.

Scientists say they have discovered the first evidence of “handedness” in the cetaceans, thought to be the biggest creatures ever to have graced the planet. Like most mammals, they display a right-side bias — presumably, because the left side of the brain controls movement planning and co-ordination.

The whales betray their right-handed tendencies by rolling clockwise when they lunge for swarms of krill. This complicated manoeuvre involves suddenly accelerating in deep ocean, expanding their enormous throat pouches, engulfing about 100 tonnes of water and krill, and ­expelling the water through sieve-like baleen plates.

In the process they roll about 90 degrees, usually to the right. But the whales change their tactics for krill near the surface, performing 360-degree barrel rolls at a steep angle — and almost ­always to the left, according to the scientists, who fitted motion-sensing tags to 63 blue whales off the California coast, and analysed more than 2800 rolling lunges.

The findings have been ­reported in the journal Current Biology. Lead author Ari Friedlaender said it was crucial for the whales to keep a close eye on krill near the surface, where they ­assembled in smaller numbers than when in deep water.

By rolling to the left, the giant hunters maintained a line of sight with their dominant right eyes. “If the whales turned to the right on approach, they would lose sight of their prey,” said Dr Friedlaender, who led the research at Oregon State University and is now with the University of California at Santa Cruz. “At the surface, a krill patch will show as a nice counter-shade to the surface light.”

The blue whale’s body can exceed the length of a competition basketball court. Its tongue alone can weigh as much as an elephant, its heart is as big as a small car and people could swim through its arteries. “Feeding is an extraordinarily costly behaviour that takes time, so being able to maximise the benefit of each feeding opportunity is critical,” Dr Friedlaender said.

“We believe this left-sided rotation is a mechanism to help achieve that. When you think about how big a blue whale is, these are massive movements that take a long time to execute. These are not squirrels racing around, they’re the biggest animals on the planet.”