A fly’s eyes are composed of thousands of individual visual receptors called ommatidia. When viewed from a distance, the images produced by these ommatidia converge into a single image. This gives the fly a mosaic-like vision. Furthermore, the more ommatidia a fly has, the clearer the image it produces. However, a flies’ eyes are smaller than humans’ eyes, so their vision is limited.
The size of a fly’s eye depends on the species and the type of fly, which is categorized in the phylum Diptera. Flies come in three main species: D. mauritiana TAM16, D. melanogaster M36, and D. simulans YVF. To measure the eye size of a fly, use the Analysis tools in Adobe Photoshop CS5 and divide the eye area by the cuticular bulge dorsal to the antenna. Then, run Wilcoxon rank tests to test the accuracy of the estimate.
Insect eyes are controlled by genes similar to those in human eyes. Their size and shape are also a result of evolutionary selection, which has led to a variety of eye shapes and sizes. According to a study published in the journal Molecular Biology and Evolution, the different size of flies’ eyes may have evolved as adaptations to different environments.
Although flies only have two eyes, they have thousands of tiny cameras. The compound eye of a fly has around 6,000 facets. In comparison, the dragonfly eye has 30,000 facets!