We see all the colors of the rainbow. We learn the helpful name Roy G. Biv to help us remember the colors in order: red, orange, yellow, green, blue, indigo, violet.
Colors are just light waves our eyes can pick up. But some animals really see the world differently than we do!
Waves through space
Light you can see is really a small part of something bigger called the electromagnetic spectrum, which includes radio waves (what allow us to make cell phone calls), microwaves (used to heat up food), visible light (all that we see), ultraviolet radiation (what causes sunburn) and x-rays (used to see broken bones in hospitals).
We can think of all parts of the electromagnetic spectrum as waves moving through space. Radio waves are huge, about the size of a football field. Microwaves are much smaller — about the size of an ant. Visible light waves are even smaller than the size of bacteria. Ultraviolet and x-rays are smaller still.
How we see light
Visible light waves pass through the hole in our eye (also known as the pupil). The reason our brain process this as color is because we have special cells called cones in our eyes that absorb these waves. Most people have three cones: blue, red and green. From those three colors, we are able to see millions of colors.
Plus or minus a cone
Some people — usually males — only have two cones. They have a difficult time telling the difference between red and green. We say they are colorblind. Are there people with more than three cones? Yes! These people — usually females — have four cones.
Animal super sight
Not all animals see the way we do. Dogs and cats have two cones and see more like colorblind people.
But some animals have a completely different way of experiencing color.
Some animals see ultraviolet rays! They have the cones in their eyes that let them see the shorter waves. It looks sort of like how we see glowing under black light. Scientists say animals see a bright glowing violet/white light.
Here’s some familiar animals and how they see color.
Bees have three cones just like us. But they see in green, blue and ultraviolet. Surprised bees can’t see red? You’re not the only one. Flowers still take advantage of bees seeing ultraviolet light with iridescent flashes of color and landing pads pointing to nectar we can’t see.
Butterflies probably have the widest visual range of any animal. They use ultraviolet markings to find healthier mates.
Reindeer use ultraviolet light to spot lichen to eat. As long as there is snow, reindeer can also track predators with UV vision they use to see a predator’s urine! Snow reflects UV light, but a predator’s urine absorbs it. It looks like black trails through the snow to a reindeer.
Some birds have four or five cones! Kestrels can track mice through their UV urine and scat, or poop. Males and females of some bird species look the same to us. But if you ask a bird they would think you were crazy. That’s because under ultraviolet light they look very different.
Sockeye salmon may use ultraviolet to help them find food.