Double-Take

How Owls Swivel Their Heads

I’m a huge fan of owls, morphology, and physiology so I had to post this. A student at Howard Hughes Medical Institute did this research as part of his masters degree. He studied how owls are able to turn their heads 270 degrees, a maneuver that would result in a human passing out due to blood flow being cut off from the brain. Owls can maintain blood flow to their brain throughout the whole process for several reasons:

1. They have twice the number of bones in their necks as humans. (14 vs 7)

2. An owl’s main carotid arteries are located just in front of the spine, close to the center of rotation, whereas a human’s arteries are along the sides of the neck. Hence, the owls damage the arteries less during head twisting and stretching.

3. Owls have larger bony cavities (about 10x bigger than humans) that are filled with air sacs. The air sacs are able to cushion the vertebral arteries during movement.

4. Owls also have multiple, smaller connecting vessels that allow blood flow to the brain even if main flow routes are closed because of rotation.

5. Thought to be most important, owls also have wide segments in their carotid arteries just under the skull base. These segments can expand and fill with blood making a reservoir of blood. This reserve of blood is thought to be a new discovery and an adaption in case there is blood flow problems from another area.

I love learning about special adaptations and their function in animals. I agree with the quote from the student that this research doesn’t really have a vital clinical relevance. But I also think he stated it well that the research “illustrates the amazing amount of biodiversity on our planet, and how there are so many things we still haven’t discovered.” I also had thought we would’ve known everything there is to know about owls, but obviously I’m wrong. Even well-known animals have some discoveries left in them, such as those from my panda article. With potent antibiotics being found in panda blood, it is impossible to say where the next major breakthrough will come from. Thus, it is critical that we do all we can to preserve biodiversity and explore all of the possibilities.

Snowy Owl. Wiki Commons: Boreal

Snowy Owl. Wiki Commons: Boreal

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