Mystery of owls spinning their heads all the way around revealed

Special neck arteries are the key

by Emily Senger

A team of scientists has solved the ever-perplexing question of how owls seem to be able to turn their heads all the way around, and they’ve picked up an international prize in the process.

The reason for the neck-turning ability is this: an owl’s neck arteries don’t go through every vertebra and, where the arteries do go through a vertebra, the canal in the bone is up to 10 times wider than the artery inside it, meaning the arteries are less likely to get damaged during rotation.

Even with the larger canals, there is still a possibility that the arteries could get pinched and stop the blood flow to the brain. But owls also have a way to get around this problem, the scientists discovered. The arteries that are at the base of an owl’s head widen and pool into reservoirs, whereas human arteries would narrow further away from the heart. “The reservoirs make for more blood flow, even if the arteries are pinched elsewhere,” explains NPR. This allows the owls to sustain the blood needed to move their heads and eyes, even as their head is turned.

The scientists at Johns Hopkins made their discovery by testing dead owls (which died of natural causes) and injecting dye into their necks to mimic blood flow, while moving their heads in real-time in a scanner.

The scientists won first prize in the National Science Foundation’s annual visualization challenge for their research and here’s the winning illustration. The research was also acknowledged in the journal Science on Feb. 1.

The study helps shed light on why humans can so easily damage their fragile neck vessels, while owls can turn their heads 270 degrees without injury.

“Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke,” said study senior investigator Dr. Philippe Gailloud in a statement.

The team plans to test hawks next, to see if they share any of the same abilities that allow owls to turn their heads.




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