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Whales are mostly right-handed, with one exception

Scientists have discovered that blue whales are essentially either “right-handed” or “left-handed” just like humans. Most of the animals were found to have a right-side bias.

The researchers used tags to track the movement of more than 60 blue whales off the coast of California. The team was not surprised to find that blue whales were more inclined to their right sides because the left side of the brain controls predictive motor control and connects with the right eye.

There was one move, however, that made right-side biased whales switch to the left side.

When they rise up from underwater toward a krill patch near surface waters, the blue whales maneuver 360-degree barrel rolls and almost always roll to the left.

Ari Friedlaender is a cetacean expert at Oregon State University who led the study.

“The patches of prey near the surface, between 10 and 100 feet deep, are usually smaller and less dense than prey patches found deeper and the blue whales showed a bias toward rolling left – presumably so they can keep their right eye on the prey patch and maximize their effort,” said Friedlaender.

“These are the largest animals on the planet and feeding is an extraordinarily costly behavior that takes time, so being able to maximize the benefit of each feeding opportunity is critical. And we believe this left-sided rotation is a mechanism to help achieve that.”

Blue whales are massive animals, weighing as much as 25 elephants and reaching the length of nearly three school buses. However, most of their diet is comprised of krill, which are tiny shrimp-like creatures.

“Most of the movements we tracked that involved ‘handedness’ – perhaps as much as 90 percent – involved 90-degree side rolls, which is how they feed most of the time,” said Friedlaender. “Blue whales approach a patch of krill and turn on their sides. We found many of them exclusively rolled to their right, fewer rolled just to their left, and the rest exhibited a combination.”

Friedlaender explained that this was the first time that such lateralization bias had been documented in blue whales. The researchers pointed out that a left lateralization bias is unusual.

“The most curious aspect was how so many of the whales exhibited lateralization to the left when swimming upwards at a steep angle to get prey,” said Friedlaender.

The research, which was primarily funded by the U.S. Office of Naval Research, is published in Current Biology.

By Chrissy Sexton, Staff Writer

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