Turtle Eyesight: Can Turtles See Color?


Have you ever wondered if how well can turtles see? Can they see color and how many colors is there in the turtles rainbow?

Turtles can see quite well both on land and under water. They can see better underwater though. They see color as well. In fact, humans can perceive light rays with a wavelength between 400 and 700 nanometers, what we think of as visible light. Turtles however can see light waves in the ultraviolet spectrum meaning that they can see colors that we cant even dream of.

It used to be thought that turtles and other reptiles could only see in black and white. But increasing scientific evidence is proving to the contrary that for turtles at least they can differential between a vast palette of colors.

According to this New York Times article, a scientific study was published reporting that turtles have a special red gene that may have originated in ancient dinosaurs. This gene allows turtles to not only be able to pick out the color red and various patterns consisting of it, but also see shades of red that we can not.

Most humans can perceives shades of red like scarlet and crimson, but turtles with this special red gene can see shades that are in between crimson and scarlet. In addition to this some turtles, such as the red eared slider can see about the highest 100 nanometers of ultraviolet light, which is something humans can see in only very special circumstances.

How do Turtles React to their Color Vision?

Many keepers of turtles have reported their turtles acting strangely around certain colors. Most of these colors occur as variations of red, yellow and orange. These reactions as you can imagine can be immensely amusing and fascinating to the turtles human keepers.

Yellow: Some people have reported their turtles have wierd fascination with the color yellow. Looking for it in their tank and in the room, some turtles love bananas and see could be the cause. Seeing that one of their favorite foods are yellow they quickly begin looking for anything yellow thinking it might be a delicious banana they can munch on.

Red: This color as reported earlier is the one wiht the most official scientific backing. Turtles can percieves subtle shades of red that are imperceptible to humans. It is difficult to think what this color might be like but the best way would be to try to picture colors somewhere between scarlet and crimson in shade. Turtles have a special gene that allows them to do this called CYP2J19. Interestingly enough they also share this gene with ancient dinosaurs, which may have been where they got it from.

Orange: Humorously some turtles see to be greatly turned off by this color. Some keepers have reported that their turtle will even hide in their shell from orange colored things. And will go great lengths to even avoid tasty fish and shrimp if they appear orange for some reason. This is very funny to think about, imagining a poor turtle hiding from the color orange. If you have a turtle it might be an interesting little experiment to try, introduce something orange and see how they respond comment below if you see anything interesting.

Turtles many various responses to color, while some being partially do to the eccentricities of individual turtles, may have something to do with finding food in their environment. Colorful things stand out in nature and often contain vital nutrients. With people there are even dietary recommendations to eat as many color of food as you can to guarantee a cornucopia of diverse nutrients and vitamins. By turtles being attracted to strange colors this serves as mother natures way of encouraging them to try to get all the nutrients they can while in the wild.

Can Turtles See in the Dark?

Animals that can see in the dark have positioned behind their eye a mirror like reflective membrane called a tapetum lucidum. This is what allows animals ranging from owls to dogs and cats to be able to have excellent night vision. Humans do not have a tapetum lucidum so therefor we depend upon our pupils dilating to be able gather what little light we can in the dark.

Ever bumped around at night while your dog or cat jaunt about gracefully as if they had a secret flash light? That’s because they in fact do. That’s their tapetum lucidum in action which works like a lens that magnifies light allowing them the best night vision nature can provide. You can see this effect too if you take a picture with flash of cats or dogs.

Unfortunately turtles do not have a tapetum lucidum. They can of course still see somewhat in the dark just like humans can, but their night vision will never rival that of animals like the common house cat or a pet dog. Just like us they must allow their pupils to dilate and acclimate to the darkness to be able to perceive.

While it is not a sure fire way, there is a way that you can tell if an animal has a tapetum lucidum or not. You have probably seen this effect with your dog or cat where their eyes sometimes glow in pictures. This is usually a good way to tell if an animal has special nightvision or whether they just have normal night vision like humans.

Mdf / CC BY-SA

Turtles Have a Special Range of Vision

Your range of vision consists of your field of view and what your eyes focus upon and how they focus. Humans and most animals have what called a vestibulo-ocular reflex or a VOR for short. This ocular reflex allows your eyes to maintain their focus on one spot even when you turn your head to the right or left. Most animals have a VOR but not all do. Chickens and pigeons for example do not, as they are always walking around with their heads bobbing so they can alternate their vision between the ground, where most of their food is located, and paying attention to where they are going.

In addition to those animals whose eyes are forward-facing (like dogs, humans and cats) and those creatures that have sideways facing eyes (deer and cows for instance), both have VOR but it works differently based upon which direction their eyes naturally face.

In animals with forward facing eyes the superior oblique eye muscle rotates their eyes away from the nose to the side. While animals that have sideward facing eyes this oblique muscles does the complete reverse! It rotates the eyes towards the nose in a inward movement.

With turtles eyes however something strange and unique happens. For example researchers discovered that with red-eared sliders, who have side-ward facing eyes but their superior oblique muscles move the eyes as if the turtles had forward facing eyes.

This was a unique adaption of turtle eye biology meant to deal with the fact that turtles can retract their heads into their shells. While turtles have eyes on the side of their head to look out for predators they also must be able to see when their heads tuck into their shell. To be able to still see well when their enclosed their ocular anatomy has to allow their eyes to then act as if they were forward facing eyes. So that they can keep watch even when their shy and scared.

If turtles didnt have this unique biological trait then they would be almost blind to danger when ever they tucked their head in their shell.

How Well do Turtles See Underwater?

Since turtles spend most of their lives under the water, they need to be able to see quite well. But large amounts of dirt and debris can be found in most pond and lakes. So how does a turtle see through that murky under water haze? Even birds of prey notorious for amazing eye sight like eagles and hawks are practically blind when smoke or fog obscured their vision.

Fortunately, turtles have developed a way to counteract this problem. The eyes of a turtle produces a special kind of tear that covers and protects their eyes. These tears aren’t like a humans tear when we cry, but instead consist of a particular kind of mucus that keeps their eyes from being affected by particles like salt and dirt as well as keeping their turtle lenses safe from water living bacteria.

Eye Diseases That Turtle Owners Need to Watch Out For

Turtles eyes are so remarkable and important to their lives. There are some problems that can develop in turtles eyes that the responsible turtle owner should try to be aware of.

The two major eye problems that can affect turtles are swollen eyelids and bacterial eye infections.

Swollen eyes: With swollen eyes the turtles conjuctiva and tear-secreting glands become heavily inflamed. This can become so bad that the eyes can swell completely shut which effectively blinds them. This can lead to malnutrition as turtles need to be able to see food in order to eat it. This can be accompanied by build up of gunk around the eye and what may seem like weeping. Breathing problems can develop as well as its possible to cause the turtles nasal passages to become blocked as well.

Eye infections: Eye infections in turtles can be accompanied by swollens eyes as well. Their can also be a connection between respiratory infections and infections of the eye. This infection will have similiar symptoms to the swollen eyes. The eyes may appear puffy and the turtle will frequently scratch or rub them. These infections can become even more deadly by spreading and causing the turtle to develope a respiratory infection. Which will have symptom such as loss of balance while swimming, excessive mucus coming out of the nose, bubbles around the mouth and loud wheezing.

If your turtles shows signs of these symptoms then you will want to take them to a vet immediately for medical care. These eye diseases are no laughing matter and can be fatal for a turtle if not promptly treated by a professional.

Conclusion Summary

Turtles can see more colors than humans can, as they can see into even the ultraviolet spectrum of light. Using a gene passed down to them by dinosaurs they can perceive a shade of red invisible to even the senses of the most skilled human artist. They can not however see in the dark like cats and dogs can, but can see as well in the dark as you and me.

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