There are all types of interesting critters in the world (discovered and undiscovered) with unique traits that often give them an evolutionary edge. Some animals can see with their eyes closed, and there are even a few animals that can see without eyes at all.
As you’ll see from this list, most of the animals that have this trait actually have transparent eyelids. Often, this serves some evolutionary purpose of keeping something out of their eyes without disrupting their ability to see what’s going on around them.
Let’s jump into this list of animals that can see with their eyes closed and why they need this cool evolutionary trait.
Skinks are one of the largest groups of lizards. Their small, thin bodies, pointed heads, and little legs are designed to help them burrow better and move through dirt underground as they search for insects to eat.
As they burrow, skinks close their eyes to keep the dirt out. They can see while they do this because of their transparent eyelids.
As the majority of skinks are ground dwellers, they spend a lot of time burrowing. In addition to being able to see without opening their eyes, they can also squeeze their body into different shapes, helping them move through small crevices.
Oriental Bay Owl
Owls are interesting creatures to say the least, with their ability to rotate their head around like something you’d see in the exorcist to their unique heart-shaped faces that work like a sonar and let them hunt using sound. The Oriental Bay Owl can even see with its eyes closed.
This specific owl can see with its eyes closed because of its big black eyes and white eyelids. Their white eyelids have small slits that essentially let this species of owl see with its eyes closed.
Most people recognize chameleons as the color-changing lizard that adapts to its environment to blend in. Not only do they change colors, but chameleons can even see through closed eyes. Otherwise, they might just look like a big pair of eyes staring at you from a branch.
Chameleons can see with their eyes closed because of a small hole in the center of their eyelid. Their eyes can also move independently of one another, making it a lot easier for chameleons to keep an eye on their surroundings and hunt for prey.
Did you know that snakes keep their eyes closed all of the time? Instead of having movable eyelids, snakes have a single eyelid that is semi-transparent. This is often referred to as a snake’s “spectacles”.
It is pretty common before a shed for fluid to build up behind a snake’s eyelid, giving it a cloudy or milky appearance. Snakes may not eat during this time and people who keep them as pets also say they get irritable.
Camels are known for their desert-friendly features like long eyelashes to keep sand out of their eyes and their large hump that stores water so they don’t get dehydrated. But did you know that camels also have three separate eyelids?
A camel’s third eyelid is called a nictitating membrane. It is thin and transparent, so it keeps out dirt and dust when sand blows around in the desert but doesn’t stop the camel from being able to see.
Camels also aren’t the only animal with a nictitating membrane. While they can’t see through their entire eyelid, cats, dogs, sharks, and some species of amphibians and birds also have a third eyelid.
Like camels, frogs have a nictitating membrane. Instead of using theirs on land, however, frogs use this thin, transparent eyelid to keep debris out of their eyes when swimming around in the pond or lake. There are other amphibians that have a third eyelid as well.
Even being clear, a frog’s third eyelid makes it a little harder for them to see. Instead of relying on their eyesight underwater, frogs rely on their sense of smell to guide them.
Frogs sometimes use their nictitating membrane on land as well. They have a bottom lid that’s stationary and can use their top lid to distribute moisture. However, the nictitating membrane can also be raised for moisture. Sometimes, frogs only raise it halfway so they get the benefits of moisture without impacting their vision too much.
The octopus can’t necessarily see the world clearly around them when their eyes are closed. However, octopi are covered in light receptors all over their skin. This means that when there are shadows or light changes in their environment, they often recognize these changes even with their eyes closed.
The octopus is also unique in the way that it uses its eyes to help camouflage itself in its environment. It can constrict and dilate its pupil as needed to blend into the environment. Plus, an octopus’ large eyes give it great vision on both sides of its head and it can move these eyes independently of one another, too.
While the platypus can’t technically see with its eyes shut, it does close its eyes while on the hunt. In fact, when a platypus dives underwater, it has muscles that close its eyes and ears to keep water and debris out.
So, how does the platypus find food? It relies on the hundreds of tiny openings found on a platypus bill. These receptors pick up on the electrical currents generated by shrimp, insects, and other prey moving through water from up to 30 centimeters away.
There are several other sea critters that also rely on similar systems to detect prey, including some types of fish and sharks.
How Can Some Animals See with Their Eyes Closed?
Often, the reason some animals see with their eyes closed comes down to surviving in their unique environment. Burrowing animals rely on their eye covering to keep dirt out of their eyes, while animals with poor sight underwater like the platypus close their eyes and rely on other senses.
Some animals also have a nictitating membrane, which is a third eyelid that is transparent to some degree. This serves the purpose of keeping debris out both on land and in water, depending on the critter. While I didn’t mention all the animals with this feature because it’s not technically being able to see with closed eyes, cats, dogs, frogs, camels, and some birds and amphibians have a nictitating membrane.
Some animals were born with this evolutionary trait hundreds of years ago, while others have developed them to adjust to their shift environment with time. Things like climate change and the impact of things like invasive species and deforestation play a big role in how animals adapt with time.
Some animals that can see with their eyes closed include certain species of skinks, owls, frogs, camels, chameleons, and snakes, to name a few.
While animals don’t necessarily develop traits because of their environment, in most cases, the ability to see with their eyes closed helps with keeping debris or water out of an animal’s eyes. For example, burrowing animals rely on this ability to keep dirt out of their eyes.
There are also several animals that have a nictitating membrane, which is a third eyelid that works independently from the rest of the eye. This thin, transparent cover keeps debris out of an animal’s eyes.
Animals really are interesting creatures, particularly when you start to think about how they change over time as evolutionary traits get passed down to offspring. Hopefully, this article has answered some of your questions about how seeing through a closed eye could give an animal an evolutionary edge.