In the past, scientists assumed turtles only saw things in greyscale. It’s now evident that they can see color and ultraviolet light too. However, does it mean they can see in the dark?
So, can turtles see in the dark? Yes, turtles can see in the dark, but not as clearly as nocturnal animals. A turtle’s vision in darkness is as good as that of a human at night. Turtles don’t need a night light and can perfectly sleep in darkness.
In this article, you will get an in-depth understanding of turtles’ vision, how well they can see at night, and more.
Can Turtle See in The Dark?
Turtles can see at night. However, their sight at night is not that great, and they can’t decipher images. Just like humans, their iris narrows, and the pupil compresses when exposed to bright light. During the night, their pupils widen to allow as much light as possible and improve sight.
Turtles, specifically the red-eared slider turtles, have unique eyes that work the same as humans. Most animals have a vestibulo-ocular reflex (VOR), a reflex that allows humans and animals to maintain focus while moving. Despite having lateral eyes, turtles’ VOR resembles that of front-facing mammals while maintaining focus. When turtles retract their head to their shells, there is less room for head movement, and they manage by this unique ocular anatomy.
In the wild, turtles are active during the day under sunlight. During the nighttime, turtles retract to their shells and sleep, only surfacing to breathe when necessary. Captive turtles can and should survive with this light circle that resembles natural lighting in their aquatic environment. They should have at least 12 hours of light to represent daylight and 12 hours of darkness for sleep.
Turtles also have underwater vision, which perfectly suits them since they are aquatic animals who spend much time in deep water. Their eyes are able to adapt when they come out of the water for breathing and basking. These aquatic creatures can also see bioluminescence, which allows them to spot prey deep under the sea. Turtles have flat corneas and an additional ability to see other wavelengths of light, like ultraviolet light.
Do Pet Turtles Need a Nightlight?
Despite being unable to see clearly at night, turtles don’t need lights on over the night. Just like humans, most turtles can’t sleep when the lights are on, which sometimes disrupts their sleep. For a normal circadian rhythm, there should be a balance between the presence and absence of light.
However, sometimes pet owners will compromise this cycle and keep the aquarium lights on at night. This is common when there are new hatchlings in the tank, who often sleep in the basking area. In this case, you can use infrared heat lamps that have less intense light, to create artificial beach lighting. The purpose of these lights is to keep the baby turtles warm and provide some light for them as they wander.
Another case is where you will need to keep the lights on if your turtle pet is sick. In this case, you can use a night light to keep the pet warm and be of viewing aid when it moves. Since they are ectothermic, turtles rely on the heat in their environment to regulate their body temperature. Keeping the dim light on will speed up their metabolism, and your sick pet will have a better chance of recovering.
Do Turtles Have a Strong Vision at Night?
You might be surprised to see your turtle moving around at night occasionally. This is perfectly normal because some species of turtles are known to be nocturnal in their natural habitats. This doesn’t mean their vision is strong, actually, it is as strong as that of humans.
Scientists have argued about whether turtles are nocturnal or diurnal animals. Some argue turtles in captivity adopt and follow the cycle of their pet parents and sleep most at night. Also, turtles lack most characteristics of nocturnal animals, like sharp senses and night vision which disqualifies them from this category.
Turtles also lack tapetum lucidum, a reflective membrane behind nocturnal animals’ eyes that enables them to see in the dark. Turtles sleep for around six to seven hours, after which they will be active, though not as active as during the daytime. Also, turtles will regularly float to the water surface to take a breath of air during the night while they sleep. They also float when busking to dry up.
Also read: Do Turtles Need a Water Heater?
Why Is It That Turtles Don’t See In The Dark?
A turtle’s vision at night is like that of a human being. If you walk out at night, at first, you will not see anything. But, after some time, your pupil grows larger, allowing you to see, though obscurely. The turtles see things like that, only that there is a red shade in their case.
But the red shade doesn’t make their vision any better. Mostly, this is because, unlike other animals like dogs, turtles don’t have a retroreflector. As the name suggests, the retroreflector returns light, allowing the animal to see images more clearly at night.
Since a turtle lacks this, it only sees images to the extent that its pupil expands, just like a human being. If you want to see the difference, you can take a photo of both animals’ eyes at night. Take a photo of your dog’s and turtle’s eyes in the dark using flash and compare.
Have you seen a cat’s eyes at night? That glow reflects from the results from the retroreflector we are talking about. You will never see this with a turtle or a human being, and that’s why we’re saying they lack night vision.
Pet parents are often curious about some of their pet’s qualities, including their eyesight strength. However, this can only mean more questions are asked and likely remain unanswered. The following are frequently asked questions on this topic and their answers.
No. Your turtle does not have many activities to engage in at night. Just like humans, they sleep at night and remain active during the day. Although their night vision is not good, you should not keep the aquarium lights on. They will distract the pet and deprive its sleep, which could affect its health.
Despite being able to move around in the dark, turtles don’t have excellent night visions. Their vision in the dark is more comparable to that of humans at night. They’re able to see figures and shapes, but they cannot completely discern images at night.
If you want to know whether your pet turtle sees in the dark, you can take a photo of its eyes. Animals with night vision have their eyes light up when you take a photo in the dark, with a flash on. Unlike owls and bats, your turtle’s eyes will not produce that glow produced by animals with night vision.
Related: Do Turtles Need Calcium?
New pet parents sometimes see their pet turtles moving in the tank at night and wonder if it’s normal. This also makes them wonder, can turtles see in the dark? The correct answer is yes, though they can see as many details as you can see in the dark. Aquatic turtles also have an extra ability to see extra color and light levels like ultraviolet light.
Adult Turtles don’t need to sleep with a night light on, which can end up costing them their sleep. However, sometimes artificial lighting will be necessary for hatchlings, though the light should be less intense. It’s best to give turtles even hours of daytime and night to keep a natural feel to their cycle.