Owls don"t need eyes in the ago of their heads to watch what"s behind them — they deserve to just swivel your heads all the method around. In fact, plenty of owl species, such together the ban owl, have the right to rotate your heads 270 levels in every direction, which method they deserve to look come the left through rotating every the method to the right, or vice versa.

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But how do they do it there is no severing their arteries or preventing blood from reaching the brain? one illustrator and a physician at the Johns Hopkins University institution of medicine teamed increase to uncover out.

"Until now, mind imaging specialists prefer me who attend to human injuries led to by trauma to arteries in the head and neck have constantly been puzzled as to why rapid, twisting head motions did no leave thousands of owls lied dead on the woodland floor indigenous stroke," said study author Dr. Philippe Gailloud, in a statement indigenous the university.

If human beings tried to rotate our heads so promptly or far, we"d tear the lining of ours arteries, which would cause clots to form and result in a punch (besides additionally breaking ours necks), that added. "The carotid and also vertebral arteries in the neck the most animals — including owls and also humans — are an extremely fragile and also highly susceptible to even minor tears that the courage lining."


Looking within owls


To get a glimpse of the owl"s blood vessels when their necks to be turning, the duo injected dye right into the blood vessels of a dozen dead owls and used a CT scan to visualize the shimmering liquid spreading throughout the birds" arteries choose blood, stated Fabian de Kok-Mercado, who performed the work while getting a master"s in clinical illustration in ~ Johns Hopkins. (He is now an illustrator in ~ the Howard Hughes medical Institute in Chevy Chase, Md.) The researchers then twisted the dead owls" heads to watch what happened.

After developing the CT scan images, the researchers injected a plastic-like substance right into the veins of dead snowy, barred and good horned owls and also dissected the animals, illustration the routes and also locations of the vessels.


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Fabian de Kok-Mercado (left) and Dr. Philippe Gailloud offer a CT scan to a dead owl come learn just how its blood vessels withstand the rapid, up-to-270-degree turns their heads make. (Image credit: Fabian de Kok-Mercado and Dr. Philippe Gailloud)

They uncovered a number of previously undiscovered and also unique traits, de Kok-Mercado told OurAmazingPlanet. For one, the owls" neck bones, or vertebrae, contain holes that space much bigger than those found in other birds or humans. In humans, the feet in the vertebra is around the very same size as the artery, yet in owls the feet is around 10 times larger than the artery, according to the study, released today (Jan. 31) in the journal Science. These holes, or canals, likely organize air sacks intended to cushion the twisting activity of the head, de Kok-Mercado said.


"We likewise noticed appropriate away that these canals were missing in the bottom two vertebra the the neck," de Kok-Mercado said. This offers the cord-like vessels part slack when the bird twists its head.

The large holes and "slack" at the bottom that the neck help explain why the vessels don"t break. Yet they don"t define why the it is provided of blood isn"t cut off once an owl turns its head — through so much twisting, the vessels room bound to come to be partially blocked.

Blood come the brain

The team noticed the the vertebral artery enlarges slightly together it viewpoints the brain, which is unusual and not watched in plenty of other animals (like the tribe of a tree, vessels generally get smaller together they gain farther from the heart). The writer think that these enlarged locations may role as reservoirs in i beg your pardon blood have the right to pool, so the the mind has extra blood to occupational with together the head swivels around, de Kok-Mercado said.

The blood vessels near the brain are also highly connected. A vessel called the patent trigeminal artery connects the front and the earlier of the owl"s brain, which helps supply the organ with as much blood as possible.

Why execute owls should crane their necks to such an extreme degree? It"s since their eyes are tubular, built virtually like telescopes, providing them impressive vision, de Kok-Mercado said. However unlike humans, who have about spherical eyes, owls cannot relocate them about easily, so they have to rotate their heads.

The recognize is just one more example of just how the birds space perfectly adapted to fit their environment, enabling them to see despite having relatively fixed eyes.

"I hope it provides people more of an evaluation of the life top top this planet," de Kok-Mercado said.

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This story was detailed by OurAmazingPlanet, a sister site to altoalsimce.org. Reach Douglas key at dmain
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