What Is Countershading?
Countershading is a pattern seen in almost every animal, in which they are darker on top and lighter on the bottom. This coloration is going to create an illusion that makes animals less visible in their environment. It works because light typically comes from above (i.e. sunlight). So, when animals are darker on top, they blend in with the darker ground below, while their lighter underside matches the sky more when viewed from below. Essentially, shadows are being cancelled out! This is going to allow both predator and prey animals to stay hidden when attempting to get food, or escape from being food!
The person who discovered an explanation for this phenomenon wasn’t a biologist or a zoologist, but a painter! Abbot Thayer is renowned for acknowledging that countershading is used as camouflage. As a painter, he knew that to make an image appear 3D on a 2D backdrop, shadows had to be involved. He observed that in the 3 dimensional world, many animals coloration actually cancelled out the shadows that their bodies created under the sun. Thayer called this obliterative shading. He believed by getting rid of those shadows, the animals then looked flatter, allowing them to blend into the background a lot easier.
This is evidently true with so many animals. With certain animals that spend a lot of time upside down, that countershading is actually reversed so that they are lighter on top, and darker on the bottom. Therefore, when they are upside down, it still cancels out the shadows and makes them look flatter.
This is exemplified further when we look at animals that live in very bright environments, like grasslands or deserts, where the shadows are stronger. Countershading on those types of animals is even more pronounced in order to still balance out those shadows.
This is a time to remember that other animals don’t see the way that us humans do. You might not think this is the case when we can see animals against backgrounds pretty well. But a human’s eyesight is generally going to be better than most other animals when it comes to detail and color! Especially when those other animals are going to depend on contrast when detecting predators or prey. So to us, they might be visible, but to other animals, countershading seems to make a difference when it comes to survival.
Countershading at Turpentine Creek Wildlife Refuge
When it comes to predators staying hidden, we have some experts here at Turpentine Creek as well! Tigers, leopards, jaguars, lions, servals, bobcats, cougars, and caracals all display varying degrees of countershading on top of their already magnificent camouflage. While it may be subtle, they all follow the trend of being darker on top, and lighter on the bottom.
Marine Life and Countershading
But its not always just to hide shadows. With land animals, they are mostly viewed from the side, and therefore this theory makes sense. But animals that swim or fly don’t have the privilege of only being perceived from one angle. Plus, in the ocean, sunlight will be scattered around, not just coming from above.
Many fish and marine life use this coloration to stay hidden. Being dark on top helps them blend in when being viewed from above, as they then get lost with the depths of dark water below them. Being light on their underside helps when other animals see them from below, as they then blend in with the lighter water above. This is especially important for those that swim in open waters with far less hiding spots.
In deep, deep waters, the only light is coming from above, and no matter how light they may be on the bottom, they will still cast a shadow against the sky. So certain animals have found ways of still keeping themselves hidden with counterillumination. They have little organs on their undersides that produce light. Sharks, crustaceans, fish, and squid have been observed using counterillumination to hide their silhouette.
In some cases, countershading might not be camouflage only. In the case of penguins, it might be an attempt to help regulate temperature! Penguins are about as counter-shaded as it gets, being completely black on the backside, and white on the belly side. While this still keeps them hidden sometimes, it might also help serve a different function. Studies have observed penguins turning their backs to the sun when cold, and their white undersides to the light when hot.
In the end, both predators and prey animals have come up with different ways to stay hidden and gain an advantage over the other. These visual tricks can take the form of different color patterns in order to confuse other animals. From an evolutionary perspective, this has seemed to work, as its been seen for millions of years across all animals. Mammals, marine life, birds, reptiles, and amphibians have all displayed countershading. Paleontologists have even discovered pigments within fossils of dinosaurs that follow this trend. If most animals share this characteristic in some form, it must be working! Whether countershading works by blending into the background, erasing their shadows, making them appear 2D, or even keeping them warm, we know its worked well enough that animals keep producing this pattern over and over again all over the world.