Humans have an undeniable love of color. We spend a considerable portion of our lives marveling at the beauty found in both nature and our own artistic creations. But what if there were colors we couldn’t even see? Imagine if our species as a whole suffered from color blindness. It might seem like a far-fetched idea at first. However, it’s an accurate description of our situation.
When we talk about color we’re really discussing a complex mix of physics, biology and neurology. When light shines on an object it reflects outward at specific wavelengths. Special receptors in our eyes called cones pick up that light and transmit it to our brain. The brain will then combine signals from both of our eyes into a singular whole. After some additional processing we become conscious of the colorful world in front of us.
It’s important to keep in mind that we’re only working with a subset of the light spectrum. We have three different types of cones in our eyes – red, green and blue. This combination of cones makes us trichromatic. The majority of mammals are dichromatic – only possessing two types of color cones.
The variety of color sensitive cones in our eyes gives us a wide view of the color spectrum. But we’re by no means able to see all of it. And in fact, there’s actually some animals which might see a more colorful world than we’re capable of. We’ll take a look at the top visual superstar of three different biological classes.
1. Birds
Birds are so commonplace that we often forget just how remarkable they really are. This species is the last remaining ancestor of the mighty dinosaurs. An argument can be made that some types of bird are among the most intelligent animals on earth. And the humble bird can also see into a wide range of colors.
It’s not really a question of whether a bird can see more colors than humans. Instead, we should ask just how much better a bird’s color vision is than ours. This might seem like an easy question to answer. Humans have red, green and blue cones in our eyes. Birds have cones for red, green, blue and ultraviolet. But there’s more to a bird’s amazing eyesight than their types of cones.
Birds have a special colored oil droplet which might let them see even more colors. What’s more, birds also have huge eyes in comparison to most other animals. It’s said that the difference between a human and bird’s worldview is comparable to that of a standard definition TV and a huge widescreen model. Birds might even be able to take in magnetic waves through a receptor in their eye to essentially see which direction they’re facing at any given time.
2. Butterflies
Butterflies are almost synonymous with color. It’s a rare individual who hasn’t marveled at a butterfly’s gorgeous wings shining on a warm summer day. Likewise, the sight of butterflies drinking from colorful flowers is a veritable feast for our artistic spirit. But it turns out butterflies aren’t just great at putting color out into the world. Butterflies also possess some of the most color sensitive eyes in the world.
A bird’s four cones are quite impressive when compared to the three found in humans. However, butterflies have a full fifteen different types of photoreceptors. It’s hard to imagine just what a butterfly is able to see. They can see the full red, green, blue and ultraviolet color spectrums. But what else are they able to see?
The fact of the matter is that we’re not entirely sure. However, researchers suspect the answer can be found in the butterfly’s own remarkable color patterns. Butterflies are impressively colorful even to our own trichromatic eyes. Just how colorful would those wings look to another butterfly?
It’s important to keep in mind that butterflies are the final, and reproductive stage, of the insect’s life. Their main purpose at this point is to find a mate and outcompete any potential rivals. All of this means that the ability to spot other butterflies takes on a supreme importance. An ability to make out subtle colors on another butterfly’s wings, even in a colorful field of flowers, would provide some significant advantages.
3. Mantis Shrimp
Mantis shrimp have a longstanding reputation for amazing eyesight. A mantis shrimp boasts up to sixteen different types of color based photoreceptors. People have assumed this means that they’re able to see a world full of amazing colors. But in reality it might not be quite so simple.
It appears that the mantis shrimp’s vision is considerably different than what we’re used to. Researchers have trained mantis shrimp to recognize specific color wavelengths. They then put the crustacean’s vision to the test. Surprisingly enough the mantis shrimp wasn’t able to properly differentiate between similar colors.
Earlier we noted that humans see color not simply by using the cones in our eyes. Our powerful brains also put a lot of work into processing the data brought in by cone cells. Things don’t seem to work quite the same way with mantis shrimp.
Mantis shrimp are incredibly speedy creatures. They hunt by essentially punching prey at a speed of 75 feet per second. This offers a clue into why the mantis shrimp’s eyes function so oddly.
Researchers speculate that the many photoreceptors are essentially looking for very specific colors. This means that they’re not working together in harmony in the same way that a human’s cone cells will. The mantis shrimp’s photoreceptors are instead able to essentially operate like an emergency line to the rest of its nervous system. Having so many photoreceptors gives it a wide range of vision, possibly similar to humans, while also allowing it to react with lightning fast speeds when it sees prey.
The mantis shrimp has another visual quirk as well. The little creatures are able to detect polarization. This aspect of vision is difficult for humans to properly conceptualize as we’re essentially blind to it. But we can think of it as a spatial dimension of light. This is particularly useful underwater as light essentially bounces off water molecules.
There’s still a lot to learn about just how shrimp see the world. The animal’s vision has been discussed considerably more often than it’s been researched. But at the moment the best we can say is that a shrimp’s vision is very different from our own.
Different Eyes and Different Minds
It’s easy to find ourselves a little envious of these three examples. But one fact might stand out as we go through the list of visual superstars. We began by looking at birds – members of the aves class of animals. Next we looked at the insecta class with butterflies. And finally, we looked into the malacostraca class of crustaceans with the mantis shrimp. But mammals are noticeably absent in this list.
The reason we don’t see mammals represented is that humans are most likely the superstar of that particular biological class. Primates generally have the best color vision of all mammals. And humans seem to be the best at seeing colors among the primates. It’s easy to be envious of all the sights other animals can see. But it’s important to also keep in mind that the typical 10 million colors a human can see is also quite impressive.
