Owls don\"t need eyes in the back of your heads to watch what\"s behind castle — they can just swivel your heads every the means around. In fact, plenty of owl species, such together the prohibition owl, deserve to rotate their heads 270 degrees in every direction, which method they deserve to look to the left through rotating every the means to the right, or angry versa.

You are watching: How can owls turn their heads all the way around


But just how do they execute it there is no severing their arteries or avoiding blood from reaching the brain? one illustrator and a medical professional at the Johns Hopkins University school of medication teamed increase to discover out.

\"Until now, mind imaging specialists like me who resolve human injuries caused by trauma to arteries in the head and also neck have always been puzzled regarding why rapid, twisting head activities did no leave hundreds of owls lying dead on the forest floor indigenous stroke,\" claimed study author Dr. Philippe Gailloud, in a statement native the university.


If people tried to rotate our top so rapidly or far, we\"d tear the lining of our arteries, i m sorry would cause clots to form and bring about a stroke (besides also breaking our necks), he added. \"The carotid and vertebral arteries in the neck that most pets — including owls and humans — are an extremely fragile and also highly at risk to even minor tears that the vessel lining.\"


Looking inside owls


To acquire a glimpse that the owl\"s blood vessels as soon as their necks were turning, the duo injected dye right into the blood ship of a dozen dead owls and used a CT scan come visualize the shimmering liquid spreading transparent the birds\" arteries favor blood, said Fabian de Kok-Mercado, that performed the job-related while getting a master\"s in medical illustration at Johns Hopkins. (He is currently an illustrator in ~ the Howard Hughes medical Institute in Chevy Chase, Md.) The researcher then twisted the dead owls\" heads to watch what happened.

After developing the CT scan images, the researcher injected a plastic-like substance into the veins of dead snowy, ban and good horned owls and dissected the animals, drawing the routes and locations that the vessels.


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

They discovered a variety of previously undiscovered and unique traits, de Kok-Mercado told OurAmazingPlanet. Because that one, the owls\" neck bones, or vertebrae, contain holes that are much larger than those uncovered in various other birds or humans. In humans, the hole in the vertebra is about the very same size as the artery, yet in owls the hole is about 10 times larger than the artery, follow to the study, released today (Jan. 31) in the newspaper Science. These holes, or canals, likely organize air sacks meant to cushion the twisting activity of the head, de Kok-Mercado said.


\"We additionally noticed right away that these canals were missing in the bottom 2 vertebra that the neck,\" de Kok-Mercado said. This gives the cord-like vessels part slack when the bird twists its head.

The huge holes and \"slack\" in ~ the bottom that the neck aid explain why the vessels don\"t break. However they don\"t explain why the it is provided of blood isn\"t cut off as soon as an owl turns its head — through so much twisting, the vessels room bound to end up being partially blocked.

Blood to the brain

The team noticed that the vertebral artery enlarges slightly together it philosophies the brain, which is unusual and not seen in many other pets (like the stems of a tree, ship generally gain smaller together they gain farther from the heart). The authors think that these enlarged locations may role as reservoirs in i m sorry blood deserve to pool, so the the brain has extra blood to work with as the head swivels around, de Kok-Mercado said.

The blood vessels close to the brain are additionally highly connected. A vessel called the patent trigeminal artery connects the front and the earlier of the owl\"s brain, which help supply the body organ with as much blood as possible.

Why carry out owls must crane their necks to such severe degree? It\"s because their eyes room tubular, built virtually like telescopes, offering them exceptional vision, de Kok-Mercado said. But unlike humans, who have roughly spherical eyes, owls cannot relocate them about easily, so they have to rotate your heads.

The detect is just one more example of exactly how the birds are perfectly adjusted to fit their environment, allowing them come see in spite of having relatively fixed eyes.

\"I hope it offers people much more of an appreciation of the life top top this planet,\" de Kok-Mercado said.

See more: Is A Parrot A Vertebrate Or Invertebrate ? Vertebrates: Birds

This story was detailed by OurAmazingPlanet, a sister site to lifwynnfoundation.org. With Douglas main at dmain
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