ASK A SCIENTIST
Question: How come owls can turn their heads farther than us?
What do wolves and owls have in common? From ancient times, people have regarded both wolves and owls with fascination and awe. Both have been feared and venerated, despised and admired. Many of the world's oldest spiritual traditions use either the wolf or the owl as symbols for wisdom and to represent great teachers. This is especially true for the owl. How did this happen?
For the owl, perhaps it is a result of the forward facing aspect of its eyes. Owls are described as having a wide range of "binocular" vision, or the ability to see an object with both eyes at the same time affording our feathered friend the ability to see objects in three dimensions: height, depth and length. While the field of view for an owl is about 110 degrees, with about 70 degrees being binocular vision, the field of view of a human is 180 degrees, with 140 degrees being binocular. In contrast, a woodcock has a 360-degree field of view, with its eyes on the side of its head, and 10 degrees of this being binocular.
Walking along a forest path at sunset, if you are fortunate enough to spot an owl I bet you will be immediately struck by how large the owl's eyes are-- permitting sight under very low light conditions. Owl's eyes are tubular in shape rather than spherical and are held in place by bony structures referred to as sclerotic rings. There is a common myth that owls can turn their head through a full 360 degrees, a complete circle. In fact, the range is limited to approximately 270 degrees, a feat surpassing even the most nimble human. How do they do this? It's all in the neck. Owls' necks are composed of 14 vertebrae in contrast to our seven vertebrae, affording the owl great range of motion.
So, we received half as many neck bones as the owl? Did we get short-changed anywhere else? In fact another area is in the number of eyelids. While we have but one, owls are equipped with three. They have a normal upper and lower eyelid, the upper closing when the owl blinks, and the lower closing up when the owl is asleep. Their third eyelid is a thin layer of tissue that closes diagonally across the eye, from the inside to the outside. This cleans and protects the surface of the eye and functions much like a windshield washer on a car.
The morale of this story is the next time anyone accuses you of being a pain in the neck, tell them how lucky they are to be human. Imagine, if that person were an owl, the level of pain would immediately double!
Ask a Scientist appears Thursdays. Questions are answered by faculty at Binghamton University. Teachers in the greater Binghamton area who wish to participate in the program are asked to write to Ask A Scientist, c/o Binghamton University, Office of Communications and Marketing, PO Box 6000, Binghamton, NY 13902-6000 or e-mail email@example.com. Check out the Ask a Scientist Web site at askascientist.binghamton.edu. To submit a question, download the submission form(.pdf, 460kb).