How Many Eyes Does a Housefly Have?
The ordinary housefly has five eyes-two large “searchers” and three tiny ones. You can easily see the two big eyes that cover most of the fly’s head. These are its compound eyes. Each one is made up of 4,000 small lenses. Everything a fly looks at appears as thousands of tiny images.
Three more eyes are arranged in a neat triangle atop the fly’s head. These tiny, simple eyes can only detect changes in the patterns of light and shadow around it. With its many eyes watching, a wide-awake fly is usually able to dodge your swatter safely.
The eye of the fly is quite complex, they contain as many as 28,000 light-sensitive structures called ommatidia grouped under the cornea. The cornea in turn is composed of an equal number of hexagonal prism-shaped structures, each forming a separate image. The final image thus formed is actually like a mosaic image.
The study reveals that specific region in the male fly’s eye helps them keep track of fast moving objects – a mechanism which they use to track female flies. Unlike female flies, which generally glide along minding their own business, male flies are constantly on the lookout for a partner.