Humans are pretty good at seeing reds, blues, and yellows, but for animals ranging from bees to reindeer, ultraviolet lights up their vision
The mug on my desk is is maybe five inches tall, weighs less than a pound, and is light purple.
One of these things is not like the other. Size and weight are properties of the mug, but color is different. Color is in the eye of the beholder.
What we call the visible spectrum -- light wavelengths from violet to red -- is the light that typical humans can see. But many animals, such as birds, bees, and certain fish, perceive ultraviolet (beyond violet). And they see a totally different world.
Here's what we're learning about the world beyond our vision:
- Butterflies are thought to have the widest visual range of any animal. Butterflies can use ultraviolet markings to find healthier mates. Ultraviolet patterns also help certain species of butterflies appear similar to predators, while differentiating themselves to potential mates.
- Reindeer rely on ultraviolet light to spot lichens that they eat. They can also easily spot the UV-absorbent urine of predators among the UV-reflective snow.
- One bird species was found to feed its young based on how much UV the chicks reflected.
- Some species of birds use UV markings to tell males and females apart.
- The flower Black-eyed Susans have petals that appear yellow to humans, but UV markings give them a bull's eye-like design that attracts bees.
- Sockeye salmon may use their ultraviolet perception to see food.
- Scorpions glow under ultraviolet light, but scientists do not know why.