Turtles are fascinating creatures that have existed for more than 200 million years. They are well-known for their hard shells and slow, steady movements, which have earned them the nickname “living fossils.” But have you ever wondered if turtles blink? In this article, we will explore this question and the science behind it.
Turtles have the ability to blink thanks to their eyelids, which protect their eyes and help keep them moist. However, turtle eyelids are different from the eyelids of most other animals. Instead of closing vertically, turtle eyelids close horizontally, moving from the outer edge of the eye to the inner corner. This allows turtles to protect their eyes while still being able to see their surroundings.
While turtles do blink, they do so less frequently than other animals. This is because turtles have a special adaptation that allows them to protect their eyes without blinking as often. Unlike humans and many other animals, turtles have a third eyelid called the nictitating membrane. This membrane is a thin, translucent layer that covers the eye and provides additional protection.
What makes a turtle’s blinking special
There are two things that makes the blinking of a turtle different from most animals, the first is the fact that their eyelids close their eyes vertically, as you can see in the slow motion video below, and the nictitating membrane.
Slo-mo video of turtle blinking
The nictitating membrane
The nictitating membrane is especially helpful for aquatic turtles, as it allows them to see underwater without getting their eyes wet. When a turtle is underwater, the nictitating membrane covers the eye, protecting it from the water’s pressure and any debris that may be floating in the water. This helps keep the turtle’s eyes healthy and free from infection while underwater.
In addition to protecting the eyes, the nictitating membrane also helps turtles regulate their body temperature. Turtles are cold-blooded animals, which means that their body temperature is regulated by the surrounding environment. When a turtle is basking in the sun, the nictitating membrane helps to shade the eyes, preventing them from becoming overheated.
How turtles see color
Here is a picture that shows on the left how we see things, and on the right how a turtle see things.
The reason why turtles are able to see more colors than humans is a gene called CYP2J19.
The CYP2J19 gene is also referred to as the red gene. This is because this gene allows turtles to see a lot more shades of red than we do.
Every animal is able to see colors because they have color receptors in their eyes, these color receptors are called cones. Humans have 3 different types of cones, and each type is able to detect a certain number of colors that they then send to the brain, where they will be processed and displayed.
Since turtles are able to see more colors than us, it’s possible that they also have more types of cones that allow them to do so.
You have to remember that one extra color doesn’t mean that you will only see it in new places, it will also affect other colors as well, this is why the images are so different.
How Turtles See Colors in The Dark
While turtles aren’t able to see in the dark any better than humans, the way they see things is a little different due to the extra colors.
Here is an example on how we see in the dark (left) and how turtles see in the dark (right).
There isn’t a very big difference, except for the fact that they see a little more red that we don’t see. In the sky where there is still a little light the difference is obvious, but in the forest where you can’t see anything there is no difference at all.
When we are in the dark, we aren’t able to see things around us immediately. It usually takes around 30 minutes for our eyes to completely adjust to the lack of light. This is why when you turn off the lights in a room, it is completely dark around you, and you aren’t able to see anything. But after you spend some time in that room, your eyes will be able to see things again. The same thing applies to turtles. They are able to see in the dark to some extent, just like us, but they will need a period of accommodation to be able to do that. The extra colors don’t influence this process at all.
I mentioned that turtles don’t see in the dark, now let me quickly tell you how we know this thing, as it’s also related to the way turtles see colors.
In order to be able to see in the dark, an animal must have a tapetum lucidum. A tapetum lucidum is a reflective membrane that is positioned behind the eye, and it acts similar to a mirror. The tapetum lucidum will resend photons back to the eye to be reconnected.
An easy way to see if an animal has a tapetum lucidum is to take a photo of the animal with a flash. If the animal has a tapetum lucidum, then in the photo you will see its eyes glowing. But if the eyes don’t glow, it means that the animal doesn’t have a tapetum lucidum.
As cameras have evolved, it’s getting harder to see this happening. Because all phones and most cameras remove things like glowing or red eyes as soon as the picture is taken. But you can try to stop the effects of your camera and take a photo with a flash of a dog and one of a turtle and see the difference. Here is one example.
Final Thoughts
In conclusion, turtles do blink, but not as frequently as other animals. Their unique adaptations, such as horizontal eyelids and nictitating membranes, allow them to protect their eyes and see their surroundings without blinking as often. These adaptations are just one of the many fascinating aspects of these ancient and resilient creatures.
I hope this article answered all of your questions about turtles and how they blink. If you have any other questions regarding turtles, feel free to leave them in the comment section, my colleagues and I regularly check the comment section and answer all the questions that we can find.
Related Questions
Should I live the lights on for my pet turtle during the night? No, turtles don’t need a light during the night. But if you want to look at your turtle during the night, you can buy a special light just for that. They are very dim, usually red or blue lights, that were created just for that purpose.
How long should you leave a light on for a turtle? The best practice is to let the lights on the same amount of time that the sun is in the sky. The winter is the only exception, because the sun is up for a very short period of time. During the winter, you leave the lights on for 10 to 14 hours.
Can turtles see humans? Yes, turtles are able to see humans very well, and they are also able to distinguish between us, based just on physical appearance.
How long can a turtle stay underwater ? It depends on the turtle, most sea turtles will be able to go for at least 5 hours without breathing, most aquatic turtles should be able to stay underwater for at least 20–30 minutes, land turtles on the other hand are not very good at staying underwater so 1 minute is the average you can expect them to be able to stay underwater. Here is a list of average times a turtle can spend underwater:
- Box turtle – 1 – 2 minutes
- Desert tortoise – 1 – 2 minutes
- Snapping turtle – 20 – 30 minutes
- Red-eared slider – 20 – 30 minutes
- Map turtle – 20 – 30 minutes
- Green sea turtle – 7 – 10 hours
- Leatherback sea turtle – 7 – 10 hours
- Kemp’s Ridley – 7 – 10 hours
- Olive Ridley – 7 – 10 hours
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