Have you ever tried to scoop up your bearded dragon from above, and he totally freaked out? You can thank your bearded dragon’s parietal eye for that.
Bearded dragons are fascinating creatures. Fascinating, three-eyed creatures. Yes, you read that right! Bearded dragons have a third eye on top of their head.
In fact, bearded dragons are not the only reptile with a parietal, or third, eye. Iguanas, tuaturas, and geckos are all examples of other reptiles that have this intriguing addition.
All the better to see you with, my dear!
Creepy or cool, however you “see” it, these reptiles have a third eye that helps them with some important life functions.
About the Bearded Dragon’s Third Eye
The bearded dragon’s third eye is called the “parietal eye.” This eye is fundamentally similar to the dragon’s lateral eyes in that it has a cornea, a lens, and a retina (source: Parietal-Eye Photoreceptors in Lizard, in Encyclopedia of Neuroscience, 2009, listed in Science Direct). No iris, though!
Unlike the lateral eyes, the parietal eye is not connected to the optic nerve; rather, it connects to the parietal gland through the pineal gland in the brain (source: Parietal Eye, in Clinical Anatomy and Physiology of Exotic Species, 2005, listed in Science Direct).
“The pineal gland is closely associated with the parietal eye. ... It converts photic stimuli into neuroendocrine messages and may play a role in thermoregulation.” (Source: Parietal Eye, in Clinical Anatomy and Physiology of Exotic Species, 2005, listed in Science Direct)
As you can see, this is why the third eye does not function the same way as the dragon’s lateral eyes. It processes and transmits information differently, and for a different purpose.
What Does the Bearded Dragon’s Third Eye Do?
What exactly does the third eye do?
Essentially, the bearded dragon’s third eye senses light and darkness (including UV light). It can also detect shadows, or changes in the light.
Because of this, the parietal eye helps regulate body temperature, hormone production, the sleep cycle, appetite, balance, and navigation. It also helps your dragon know if it is night or day. And it warns your dragon of oncoming predators like snakes and hawks.
Has your bearded dragon ever become severely stressed going from inside to out in the sun? The third eye is probably the reason, as it can be an adjustment to register all that UV light all of a sudden.
The Parietal Eye and Sleep
How does the parietal eye impact your bearded dragon’s sleep?
We already discussed how the parietal eye connects through the pineal gland in the brain. The pineal gland produces melatonin, which is a hormone that helps regulate the sleep cycle. The parietal eye aids in the production of melatonin. So the third eye tells your dragon when to sleep and helps them sleep well.
It's interesting to note that many nocturnal lizards do not have the parietal eye—they don’t need it to help them sleep, but dragons do (source: Parietal Eye, Martin P.C. Lawton, in Reptile Medicine and Surgery (Second Edition), 2006, listed in Science Direct).
This just goes to show how important the third eye is in regulating your dragon's circadian rhythms.
What Does the Third Eye NOT Do?
So now you know the important role the third eye plays in your bearded dragon’s day-to-day functioning. Here are some things it does not do:
- It does not see images.
- It does not register color.
- It does not detect shapes.
- It does not blink.
What Does a Bearded Dragon’s Third Eye Look Like?
If you have a bearded dragon, you know that the third eye doesn’t look like an eye. It isn’t very obvious to find, either. In fact, the third eye is tiny and discreet, hidden under a scale. It is located on the back of your dragon’s head, slightly below the space between their other two eyes. It looks like a little gray or black speck.
The best way to locate the eye on your dragon is to observe your pet carefully. You can do so while handling her or just by watching her during playtime. Just make sure you don’t approach your dragon directly from above, or she’ll think you’re a predator.
Fun Facts about Bearded Dragon Vision
Now that you know what the parietal eye does, here are some fun facts you might want to know about your bearded dragon’s vision (you know, from their lateral eyes!).
- Bearded dragons see more color than we do. Bearded dragons can see a spectrum of color that humans can’t imagine. This is because they have four distinct cones in their eyes, whereas humans have three. Crazy, right? So they have better vision than people in that regard. Additionally, they can see UVA light. Can you try to imagine what that looks like?
- Bearded dragons don’t have good night vision. As diurnal creatures, bearded dragons typically sleep at night. So they aren’t active at that time, and have no need for sharp nighttime vision. They can’t see well in the dark or in low lighting conditions.
- Bearded dragons can see forwards and over their shoulder at the same time. Because of the location of their lateral eyes, bearded dragons can see a wider range than humans can. Basically, bearded dragons can see a little bit of what’s in front of them and a little bit of what’s behind them at the same time.
- Bearded dragons have poor depth perception, but sharp long-distance vision. Because their eyes don’t see straight ahead, bearded dragons have limited ability to focus on what is directly in front of them. They can see far into the distance, though, which helps them hunt insects.
Taking Care of Your Bearded Dragon’s Third Eye
It may not be as fearsome as the eye of Sauron, but the tiny third eye of your dragon is still pretty awesome. At this point, you might be wondering, does your bearded dragon’s third eye require any special care?
All it requires is good husbandry practices and a few considerations:
- Never approach your bearded dragon directly from above. If you hover over your dragon, the parietal eye will perceive you as a predator. Make sure you are in your dragon’s actual line of vision (so they can see you with their lateral eyes) when you approach.
- Make sure the terrarium is completely dark at night. Your dragon’s light and basking lamp should be on for twelve hours during the day and off for twelve hours at night. If you leave the light on in the terrarium, your dragon won’t be able to sleep. Because the parietal eye helps regulate circadian rhythms, it can really disrupt your dragon’s natural processes if you leave a light on at night. Their appetite, hormone regulation, sleep, and energy levels can all be negatively affected.
- Make sure your terrarium is set up properly. For so many reasons, it’s vital to set up your dragon’s terrarium correctly. Here are some core rules to remember:
- Use a high quality UVB lamp.
- During the day, ensure the basking spot is 95 to 110 degrees Fahrenheit, with the rest of the tank being cooler.
- Nighttime temperature should be 65 to 75 degrees Fahrenheit.
- Make sure you know what to do if your dragon goes into brumation.
Takeaway: Your bearded dragon has three eyes. The third eye, or parietal eye, perceives light, dark, shadows, and UV light. Bearded dragons can see more color than we can and have good long-distance vision, although their nighttime vision is not very good. The third eye doesn’t require any special care—just replicate their natural habitat as best you can.
Sources & Further Reading:
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