If you have pet turtles, then you probably know this to be true. Turtles are sneaky creatures, and they often come out on the cover of the night to explore their aquarium. You must have spotted your turtle walking around at night – especially sea turtles, who are nocturnal breeders and lay their eggs at night. To do so, it is evident that they need to look clearly in the dark.
An interesting question that arises here is: can turtles see in the dark?
The answer to that is: yes, turtles can see very well in the dark. Unlike other animals, they do not possess night vision. Their eyesight is very similar to that of a human being.
Consider this: if you are in a dark room and suddenly bright lights switch on overhead, your first response will be to blink furiously, and then slowly, your eyes will adjust to the light. Similarly, if you are in a brightly lit room, and all the lights go out at once, your eyes will be able to make out shapes in the dark. It is the same case for turtles. Their eyes eventually become well-adjusted to their surroundings at night, so they do not need night vision.
This behavior does not make turtles nocturnal animals, though. Nocturnal creatures often rest during the day and wake up at night to explore their surroundings. Turtles do not do this. During the nighttime, turtles will try to identify a safe space to rest.
To know more about how to care for your turtle, check this.
Can Turtles See In The Dark?
As mentioned earlier, turtles’ vision is similar to that of humans. Just like us, the turtles’ eyes adjust to the dark eventually. There is a significant difference between the human eye and the turtle eyes. For humans, once our eyes get accustomed to the darkness, we can see things around us faintly or make out big blocks of items around us.
Unlike humans, turtle eyes can make out objects around them with a red hue. This ability allows them to see as almost as clearly in the dark as they can in the day.
Now that we have established that turtles can, indeed, see in the dark, let us take a look at how a turtle’s vision works and to what extent do turtles’ eyes allow them to see.
How Do Turtles See Colors?
Another popular question apart from ‘Can turtles see in the dark?’ is: ‘Can turtles see colors?’. A lot of humans believe that a turtle’s vision is not advanced enough to see colors. Some also think that turtles are color blind.
This assumption is false. Turtles can see colors, and what’s more, they can see more colors than human beings.
It might come as a surprise to you when I say this, but humans cannot see the color red.
Even though humans have good eyesight, we can only see colors of three wavelengths of light. Those wavelengths are red, green, and blue (also commonly known as RGB). We can only see colors that are a result of three wavelengths of light clashing together.
It is mind-boggling how many colors these three colors can produce. A turtle can see more colors compared to this!
The reason why humans cannot see red is that red has many extra shades. Humans can only see a limited number of reds compared to a turtle.
CYP2J19 or The Redness Gene
Turtles see differently than we humans do, even though we share many similarities. One glaring difference between us and the turtle species is the gene named CYP2J19, or simply put, ‘the redness gene.’
The Origin of CYP2J19
Researchers trace the origins of this gene back to millions of years ago. The first animal to have the gene is a dinosaur who had a peculiar build; it had the body of a crocodile, the snout of a pig, and the stomach of a turtle. People believe that the dinosaur passed down this gene, and now turtles and birds possess it.
The main difference between the shade of red that we see and the turtles can see is that our eyes can only see crimson and scarlet, whereas we are ‘color blind’ to the colors in between. There are more shades of red that we do not know.
Turtles use these in-between colors to enhance their vision. When the turtles hunt underwater or spend time underwater, they can see more shades to investigate better.
Yellow and Orange Colors
Research has shown that turtles are strangely attracted to the colors red, yellow, and orange. We read earlier why red draws them. But some turtle owners have observed that when there are yellow or orange objects around them, turtles see them and try to investigate.
Turtles do this because they are trying to figure out if they can eat that object.
How Do We Know That Turtles Don’t See In The Dark?
Turtles can see things in the dark, but they do not have night vision. Turtles also cannot inherently see in the dark. It is something that they develop.
Do That Mean Turtles Have Night Vision?
Night Vision is when your vision in the dark is as clear as your vision during the day. Most nocturnal creatures possess night vision. For turtles, this is not true because they do not have ‘tapetum lucidum.’
What is ‘Tapetum Lucidum’?
‘Tapetum Lucidum’ is the tissue in the eyes which are behind the retina. This tissue acts as a ‘retroreflector,’ meaning that the tissue’s job is to refract light and help us see better in situations where lighting is low. The retroreflector passes the photons in the eyes. Nocturnal animals like owls depend on this tissue to be able to see in the dark.
Remember, turtles can see in the dark. But they have to adjust their eyes to do so.
Can you prove it?
In the case of turtles, you can quickly. Check if they have night vision or not. You can do this little experiment using your phone. Simply click a picture of your pet turtle using the flash of your phone. The eyes of the animals who have night vision will glow in the image. On the contrary, your pet turtle’s eyes will not.
This experiment is proof that turtles do not have the extra ability to see in the dark.
Can Turtles See Underwater?
Unlike humans, turtles have excellent vision even if they are far underwater. Turtles can see as clearly underwater as human beings can during the daytime. Even popular pets like the Red Eared Sliders can see and live underwater adeptly.
This trait is fascinating because, as mentioned earlier, humans and turtles share the same kind of vision. So, what makes a turtle better here?
Turtles’ Vision Underwater
Turtles are aquatic and semi-aquatic animals.
A turtle lives underwater, but it needs to come out to breathe occasionally. It is essential to understand two things here: first, turtle eyes, and second, how far they can see.
How do Turtles See Underwater?
Humans have a curved cornea in the eyes, which refracts light. This trait helps us to see clearly. However, the cornea cannot do the same thing when we go underwater, and we have fuzzy eyesight. For turtles, there is a slight difference. Just like other animals who need to see underwater, turtles have flat corneas and spherical lenses. Through these, turtles have a similar vision to ours when they are above water. The cornea of the turtle will serve as a protective layer for them.
Even though there is not much difference between the turtles and us, the eyes of a turtle produce mucus (which we humans do not), and it is their body’s defense mechanism.
Funnily enough, turtle owners sometimes mistake this mucus for tears and believe that their turtles are crying. But it is just this ocean salt secreting through the eyes of a turtle. It prevents excess salt from the ocean or bacteria from getting into the turtle’s eyes.
Dirt in the water is the only thing that prevents the turtles from having a clear vision underwater. It becomes a bigger problem when the turtles live in captivity because tank water is likely dirtier than ocean water.
Keep in mind that dirty water will damage the eyesight of your turtle if not regularly cleaned.
How Far Can A Turtle See?
Turtles need little light, even underwater, to navigate their way. Naturally, turtles have to be farsighted. The flat cornea helps the turtle to see well underwater. But when they come out, they are pretty near-sighted on land.
Eye Problems in Turtles
As someone who cares for turtles, you must keep yourself up to date with pet medical advice. To maintain the good health of your turtle, you must identify any eye illness that your pets face and treat them accordingly. There are two primary underwater diseases that turtles seem to suffer from:
Eye infections are related to Respiratory Tract Infections. Sometimes these infections can also cause other respiratory disorders. They are because of certain deficiencies or poor living conditions. Some symptoms of this include puffy eyes, reddening of the eyes, loss of balance when swimming, etc. You can prevent them from happening by testing water regularly and giving your turtle a balanced diet.
Swollen eyes are a sign of vitamin deficiencies. This lack causes their eyes to swell and become puffy. If not treated in time within a short period, it might even render your turtle blind. Symptoms of this disease can be weight loss, turtles might stop eating, and swollen eyelids.
For both these illnesses, you must consult a licensed veterinarian for timely treatment and pet medical advice to make sure that you keep your turtle’s eyesight unharmed.
Should I Leave The Lights On For My Pet Turtle During The Night?
Your pet turtle will not appreciate it if you keep your aquarium lights on at night. Like most animals, turtles need adequate sleep. Even if turtles are underwater, having a light on will serve as the only hindrance to good sleep. The bright lights will not only prevent your turtles from sleeping deprived, but they might also fall sick.
One reason for keeping a bright light on during the night is to check on your turtles. However, this reason is not worth upsetting the sleep cycle of your pet turtle.
The turtles’ vision underwater will only improve in the dark if we give them the freedom to explore the tank at peace. If you would still like to have some light, consider getting a small night light for the aquarium.
Do not worry about whether or not the turtles’ vision will improve, and keep the lights off. The chances are that they will enhance their vision themselves through nightly excursions. They do not need more light.
Having darkness around the tank will stimulate a night sky for them and help them sleep better.
How Long Should You Leave A Light On For A Turtle?
Even though, as a turtle owner, you might be tempted to leave a small light on for your turtle, it is not advisable.
Sometimes, you should keep the lights on, depending on the location of the tank or the natural light that touches the tank. Usually, during the winters, when sunlight is low, you can switch on a light for the tank for a few hours in the day.
If there is enough natural light, let the tank stay the same way.
As mentioned earlier, at night, let the turtle rest by providing darkness.
Can Turtles See Humans?
Yes, turtles see humans very clearly. Most turtles are also able to distinguish between different people if they see them regularly. Since their vision has a red-colored primary tint, they will be able to see a red-shaded human. But it does not matter as long as they can see you!
What Do Sea Turtles Do at Night?
At night, if they are not exploring their tanks, turtles prefer sleeping. Sea Turtles are diurnal creatures. So they like tucking themselves into a nook or digging a hole and resting!
As we have seen, the eyes of a turtle are perfect for them to see in the dark and explore their surroundings. Not only can they use this ability to roam at night, but they can also identify food through it, as we have seen with the other colors.
Turtles are adept at underwater vision and can see very well, even in the absence of light.
As charming as they are, turtles can also suffer from diseases that You can avoid with care. Make sure to keep the water tank clean and feed a balanced diet to your turtle.
Interested to know more bout turtles? Also read whether turtles can run, or do box turtles bite, here!