Eye design is marvelously complex. Human vision, with its rods and cones, is just one method of seeing, but other life forms have methods allowing them to see wavelengths we can’t see. Insects have compound eye structures consisting of individual units called ommatidia. Under the lens of each ommatidium, a transparent structure called a rhabdom stores photosensitive pigments known as opsins. Various types of opsins can detect different colors. The more kinds of opsins an insect has in its rhabdom, the more colors it can see.
Each insect has a different set of opsins depending on what it needs. Bees, for example, have a large combination of opsins, allowing them to see many colors of flowers. Some butterflies have opsins that enable them to see a particular plant. For example, monarchs can see milkweed plants, which their caterpillars need for nourishment. Dragonflies have a set of opsins that enable them to see ultraviolet light that human eyes can’t see. Dragonflies eat other insects, including some that are underwater, and ultraviolet vision allows them to see their prey.
The fossil record shows that insects used this method of color vision before the color vision method used by humans. Eye design is marvelously complex and highly designed to allow life to function in a world that needs balance and control. The more we see of the creation of living things, the more evidence we see for intelligence and design in the world around us.
— John N. Clayton © 2024
Reference: Smithsonian Magazine for December 2024, page 88.