Most animals cannot see ultraviolet light, but there are exceptions including some butterflies, insects, and maybe Claude Monet.
Bees, important for distributing pollen, can detect some UV light. (Credit: Wikimedia Commons - Jon Sullivan)
Ultraviolet, or “UV,” as it’s often called, is probably best known for its propensity to give us sunburns. In many parts of the world, we are inundated with products that claim to protect us from this harmful form of light. Of course, too much sunlight can be damaging to human skin, but UV also provides health benefits including the production of bone-strengthening vitamin D.
For most living creatures on Earth, UV light falls outside of what can be seen. Many fruits, flowers, and seeds, however, stand out from their backgrounds more distinctly in UV light than in visible light. This has led some insects such as bumblebees to develop receptors that are sensitive to UV. Also, certain types of butterflies can detect UV and use it for communication and even in their mating practices.
In humans, there is a rare condition that lets a small number of people detect UV light. For those with this disorder, known as “aphakia,” they lack a lens in their eye. The lens normally blocks UV, so with aphakia, specialized cells at the back of the eye can activate when exposed to UV light. In some cases, this means people with aphakia can actually detect some UV light that appears to them as a whitish-blue or whitish-violet color. One report suggests that Claude Monet, the famous Impressionist painter, acquired aphakia when he had a cataract removed at the age of 82. This may have given him the ability to see “extra” color in his final years of painting.