There are a lot of things that we still don’t know about tortoises, but with every year that passes, we learn new things about them. One question that has been recently answered is how tortoises see in the dark.
Tortoises can see in the dark, but only up to a certain extinct. They don’t have night vision like some other animals do, but their vision can adjust to the darkness up to a certain point.
To better understand how tortoises see in the dark and how they see things in general we first have to understand how they see colors.
How Tortoises See Colors
Until a few years ago, it was believed that tortoises don’t have a very good vision, and some people believe that they don’t even see colors. But recent studies have shown not only that tortoises are able to see colors, but that they are able to see even more colors than us.
Here is a picture that shows on the left how we see things, and on the right how a tortoise could possibly see things.
The study has found that tortoises and birds possess a gene called CYP2J19. This gene has been traced back 250 million years to a dinosaur called Archosaur. The Archosaur is a strange creature, it is believed that he had scaly skin, and a head similar to a bird but instead of a beak it had a snout similar to a pig and that it had a shell on its belly. It probably didn’t look as bad as this description, but those are the only things that are similar in appearance.
The CYP2J19 gene is also referred to as the red gene. This is because this gene allows some bird and tortoise species 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, this color receptor is called cones. Humans have 3 different types of cones, and each type is able to detect a certain number of colors that they can then send to the brain where they will be processed and displayed.
Since tortoises 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.
Now that we know how tortoises see colors, let’s see how they see in the dark.
How Tortoises See in The Dark
Tortoises are able to see in the dark the same way we are able to do so, the only difference is that they will see colors a little differently. Here is an example of how we see in the dark (left) and how tortoises 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 tortoises. 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.
How We Know That Tortoises Don’t See in The Dark
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 on your camera and take a photo with a flash of a dog and one of a tortoise and see the difference. Here is one example.
Why Tortoises See Differently Than Us
So, it’s quite clear that tortoises can see more colors than us, but things weren’t always this way. At one point in history, humans were able to see just as many colors as tortoises do. But due to the way we evolved we gave up a few genes that allowed us to see the “extra” colors. Tortoises on the other hand decided to keep them.
The extra colors that tortoises can see are extremely useful when they are trying to spot predators and food.
Humans have evolved to live in groups that lived in small communities, that over time grew bigger and bigger. And instead of hunting and foraging for food, we started to tame animals and farmland. So over time the extra colors didn’t help us too much, so we reallocated the resources that were used for those extra colors somewhere else.
Since those kinds of changes take thousands of years to take place we can’t exactly say for sure when it happened, but we know for sure that humans were also able to see the extra colors at some point.
How the Way They See Influence the Daily Life of Tortoises
The way we see things has a huge influence on us, and the same thing can be said for tortoises.
While tortoises don’t have a favorite color to influence their choices, the fact that they see more red than us will drastically influence their behavior. Let me give you an example.
A tortoise gets out of the pond to look for some berries to eat. If the vegetation around the berries is full of life and it’s green everywhere, the tortoise will be able to spot the berries immediately. As the predominant color is green, red berries will be easy to spot.
But if it’s autumn and the whole area is covered with dried-up leaves, the berries will be much harder to spot. While we would see the leaves yellow or orange, the tortoises will see them red and orange. Here are a few pictures for you to see the difference.
This is how we see:
This is how tortoises see:
Related Questions
Should I live the lights on for my pet tortoise during the night? No, tortoises don’t need light during the night. But if you want to look at your tortoise 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 tortoise? The best practice is to let the lights on for the same amount of time that the sun is in the sky. 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 tortoises see humans? Yes, tortoises are able to see humans very well, and they are also able to distinguish between us, based just on physical appearance.
How do sea turtles see underwater? The vision of a turtle is the same on land as it is underwater. They are able to see the exact same things and the exact same color.
The only impediment to their vision can be the dirty water. If the water is dirty and unclear, the turtles won’t be able to see as far. But those kinds of things affect everybody. Even eagles who are known for their great vision, can’t see anything if they are caught in smoke or in fog.
There is something that allows turtles to maintain their good vision underwater, and that we don’t have. And that thing is found in their tears. Turtle tears contain some kind of mucus that covers their eyes and allows them to see underwater without their eyes being affected by the salt or bacteria that lives in the water.
When I say tears, I mean the kind of tears that help the eyes stay hydrated, not the kind of tears we produce when we cry because we are in pain, or due to emotional reasons. Even if they are similar, they appear for different reasons. And turtles don’t cry because they are in pain or anything like that.
Some people still believe that sea turtles will cry due to pain when they lay eggs. But what sea turtles actually do is they eliminate the excess salt through tears, it has nothing to do with pain.
Hello,
If you enjoy the content that we create, please consider saying a "Thank You!" by leaving a tip.
Every little bit can help us tremendously in continuing to create quality content that helps turtle and tortoise owners around the world.
We really appreciate the kindness and support that you show us!