Butterflies are known for having the widest visual range of all wildlife. With a larger visual field than humans and excellent perception of fast-moving objects, their keen sight could be why the species is so abundant. All butterflies have the ability to distinguish ultraviolet and polarized light through their photoreceptors, the light detecting cells in color vision. But while butterflies have the gift of extraordinary sight, the Australian Swallowtail butterfly puts them all to shame.
Like humans, most insects have 3 classes of photoreceptors. Butterflies generally possess 4 classes of receptors which are responsible for their wide visual range. The Swallowtail, however, boasts a whopping 15 different types of photoreceptors! These receptors are used to identify ultraviolet markings for use in mating and pollination purposes. A study in Japan of 200 male Swallowtail butterflies found that each class of receptor is stimulated by different colors. For example, some flowers present a visual contrast when pollinating while green light is triggered during egg laying.
Butterflies use light to search for food, find potential mates, recognize predators, and distinguish nectar in flowers. The nectar color guide of the horse chestnut tree will change from yellow to red when nectar is no longer in production. Butterflies will use these cues to determine which blossoms are capable of pollination. Butterflies also possess ultraviolet patches to distinguish themselves. Some butterfly species may look identical, but often male and female butterflies will differ only by their ultraviolet markings, while others will display significant visual differences.
Humans have the ability to decipher the world’s features with a variety of senses and tools. Butterflies are left to rely strongly on their sense of sight to keep their species thriving. Through these photoreceptors and ultraviolet markings, butterflies will be able to continue to flourish in an ever-changing world.
