Posts Tagged ‘bird eye’
The Bird Eye – An Organ Wild Animals Cannot Live Without
There are several terms that people associate with birds. One is “this is for the birds.” Or someone may refer to something fast as “swift as a bird.” People even refer to having a bird’s eye view of something. This means that something is being observed from a high vantage point. But how much does the bird eye actually see, when compared to the human eye or the eye of another animal?
Did you know that your eye and the bird’s eye have many of the same structural features? Both the human eye and the bird eye have a cornea, retina, iris, lens, anterior chamber and eyelids. Some of these structures function in the same way for both humans and wild birds/domesticated birds. The obvious difference is the size of the eye in comparison to the rest of the body. A starling’s eye is 15% of their body mass, whereas a human’s eye is only 1%.
The size of the eye depends on the bird species. Owls, for example, have huge eyes that allow them to take in more at once. For a wild bird that is important because it means that they can spot enemies and their prey much easier. Owls cannot move their eyes so they rotate their heads. How far do they rotate their heads? They rotate a whopping 200 degrees. Another difference to be found is the number of eyelids a bird has over humans. The human eye only has an upper and lower eyelid.
All species of birds have three eyelids. They have an upper, lower and a nictitating membrane that cleans and protects the eye. Another difference is in the positioning of the eyes. Humans and most wild animals, especially predators, have eyes that are not as centralized as a bird’s eye. A bird’s eye is on the front of the skull and they lack the ability to see very far to the sides. This is why birds turn their heads often.
The bird eye is fascinating. Though it is very similar to a human’s eye, it has enough differences as to allow the bird to flourish and survive out in the wild. A wild bird that does not have the correct vision or positioning would face a very dire situation when protecting itself or finding food for survival. If you want to know more about the avian eye, then go to your local library and check out a book about birds.