Chameleons are some of the coolest, most unique creatures on our planet. They also make really fascinating and fun pets for reptile enthusiasts. But when it comes to understanding their quirky behavior, it can often leave us scratching our heads (or Googling to find the answer)!
One of these questionable behaviors is sitting with their mouth open, also known as “gaping”. While it may look like a big yawn, it could actually indicate a number of things that range from normal behavior to life-threatening concerns.
So, if you see this behavior, you might ask: Why does my chameleon have his mouth open?
If you see your chameleon sitting with their mouth open, it could mean they’re simply shedding, feeling stressed, or being territorial. However, prolonged gaping can mean that your chameleon is overheating, has a mouth injury, or has a bacterial mouth infection or respiratory infection. That’s why it’s important to pay attention to this behavior.
We’ll dive deeper into the five most common reasons why your colorful friend might have their mouth open, and what you can do to address it below. We’ll also touch on a few less-common reasons so you have all the answers you’ll need when it comes to this interesting chameleon behavior.
Reason 1: Defensiveness Due To Stress Or Fear
One of the most likely reasons why your chameleon has his mouth open is because it perceives you, your pet(s), or anyone else in the room as a threat.
In the wild, chameleons have very few natural defense mechanisms, making them extremely vulnerable to predators. The best way for them to protect themselves against perceived threats is to appear as big and intimidating as possible.
To do this, a chameleon will inflate their entire body, curl their tail up, and puff their throat out as far as it will go. They will open their mouth wide and their colors will drastically change.
Depending on the species, they can become vibrant with bright colors of the rainbow, or they can become really dark and appear almost black.
If the perceived threat persists, the chameleon will draw their front arms up toward their body and begin to hiss, twist and lunge toward it, warning of an incoming bite. If it continues to feel threatened enough, it will bite.
In captivity, chameleons may act this way toward you or anyone else in the room that they feel threatened by. Simply walking by or interacting with them in any way could trigger them into a defensive posture.
So, what should you do if this happens?
First, it’s important to understand that this means your chameleon is very stressed, and chronic stress weakens a chameleon’s already delicate immune system.
If your chameleon seems very defensive around you, step away or walk out of the room to give them time to decompress. Allow a few minutes to pass, then you can check back in to see if their defensive posture has gone down and their mouth has closed.
Learn to identify the 5 most obvious signs of a defensive chameleon, including gaping, in this video:
Reason 2: Territorial Behavior
One of my favorite things about chameleons is their sassy personalities. They may be small, but they are fierce!
By nature, chameleons are solitary creatures and are known to be very territorial. They’re not afraid to put up a fight against any intruders that wander into their space.
Since captive-owned chameleons require such attentive care, their owners often have to spend a good amount of time inside their cages. If you are in your chameleon’s cage cleaning, feeding, or misting them, their territorial nature may come out as if to say, “Hey! Get outta my house!”
They will show you their “angry” colors, an open mouth, and a whole lotta attitude.
Another way this territorial behavior could come out is if you have more than one chameleon in the room and they can see each other (especially males). Even if their cages aren’t close, chameleons have excellent eyesight, so they might see each other from across the room and put on their open-mouthed displays.
To keep them from stressing each other out, put a visible barrier between the two cages or place their cages in separate areas of the room where they can’t see one another. By doing this, any territorial gaping behavior should subside.
Reason 3: Regulating Body Temperature
Like most reptiles, chameleons are cold-blooded. This means they’re unable to generate their own body heat and must rely on the temperatures in their environment to warm up or cool down.
In the wild, chameleons will make their way up to the tops of trees where they can bask in the sun to warm up as needed. In captivity, however, we must replicate the sun for them by creating a basking spot with a lighting source that emits heat.
If you see your chameleon opening their mouth while sitting in their basking spot, it’s likely because it has gotten too warm and is overheating. Similar to how a dog pants or we sweat when we’re hot, a chameleon opens their mouth to let hot air out in an attempt to bring their body temperature down.
The same can happen if you take your chameleon outside for some natural sunlight. Even if the temperature is comfortable for you, it might be too warm for your cham.
Make sure to pay close attention in either situation, because if the chameleon is overheated for too long and unable to cool off, it could be fatal for them.
In most cases, chameleons will move themselves to a cooler area in their enclosure once they warm up. But if you notice your cham isn’t moving from their basking spot or if they’re outside in the sunlight with no cover, you’ll need to step in and bring their body temperature down.
Try shutting off the basking light for a few minutes or, if outside, bring them inside or into some shade. This should help cool them off and they’ll eventually close their mouth.
Reason 4: Stomatitis
Stomatitis, also known as “mouth rot”, is a type of bacterial infection that can easily spread through your chameleon’s mouth and into their esophagus.
While it’s usually caused by an injury to the mouth area, other contributing factors can be chronic dehydration, poor nutrition or vitamin deficiency, and stress.
If left untreated, it can lead to painful inflammation and mucus deposits around the mouth, causing the chameleon to open their mouth from discomfort.
Signs to look out for are yellow discharge and swelling around the mouth/lips, mucus-like saliva, and dark deposits on the teeth or gums. Your poor chameleon could also become uninterested in eating and drinking if the infection advances enough.
If you suspect your chameleon might have stomatitis, contact your veterinarian for advice on proper cleaning and treatment.
Reason 5: An Upper Respiratory Infection
Perhaps the most concerning reason why your chameleon could have their mouth open is due to an Upper Respiratory Infection (URI). This happens when your chameleon is having difficulty breathing and is usually the result of environmental factors such as improper housing and high humidity levels.
In the early stages of a URI, you may see your chameleon holding their head stretched upward to allow for better airflow into their lungs. In later stages, your chameleon will hold their head stretched upward with the mouth open, as they’re gasping for air.
If you notice this behavior and there also appears to be mucus or bubbles coming out of your chameleon’s mouth or nostrils, this means their situation is dire and they need immediate medical attention to survive.
Regardless of the stage you find your chameleon in, I would recommend contacting your veterinarian and scheduling the soonest available visit to give your little buddy the best possible chance at recovery.
A URI must be treated with antibiotics and will only grow worse and eventually lead to death if left unattended at home.
Other Possible Reasons Your Chameleon Has Their Mouth Open
Some other reasons why your chameleon could have its mouth open that are less common, but worth mentioning:
Reason 6: During shedding
You may notice your chameleon stretch their mouth open wide and make a quivering motion when shedding to loosen the flaking skin around their face and body.
Although it looks quite alarming, this is normal behavior and nothing to be concerned about. It’s also difficult to catch as it happens quickly during the shedding process.
Reason 7: A mating display
In the wild, males put on the same dazzling display to attract females and ward off any potential competition. If you house a female chameleon in the same room, chances are your male cham will know she’s there and instinctively want to put on a show when he sees her.
Reason 8: Injury or deformation
If your chameleon’s jaw is injured from a fall or a fight with another chameleon, or if they have Metabolic Bone Disease (commonly known as MBD), they could have problems closing their mouth and even eating. It’s important to consult with your veterinarian if this is the case as either situation could lead to death.
It’s Not Because They’re Yawning
Some owners may see their chameleon open their mouth wide and think, “Look how cute, it’s yawning!”
But while it might appear to be what we’d picture a chameleon yawning to look like, there isn’t enough scientific evidence to suggest that chameleons actually do yawn — at least not for the same reasons humans do.
So, for now, the yawning theory remains unreliable.
If your chameleon opens their mouth, it’s more likely because of one of the reasons listed above.
Should You Worry If Your Chameleon’s Mouth Is Open?
Most of the time, this behavior is normal and nothing to worry about. Gaping out of defensiveness or due to their territorial nature is quite common for these feisty little reptiles.
However, if you notice that their keeping their mouth open for a prolonged time, or anything else seems a bit ‘off’ with your chameleon, it could be a sign of an underlying issue or illness that needs attention.
Look for any changes in their behavior or eating habits and for signs of overheating or trouble breathing. Also be sure to regularly check that your chameleon’s temperatures, lighting, and humidity are all at the recommended levels for the type of species you own.
It’s worth noting that chameleons are experts at hiding illness so they don’t appear more vulnerable to predators in the wild. For this reason, it’s best to keep a close eye on your chameleon, and don’t hesitate to contact a veterinarian if you have any concerns.
Final Thoughts
There you have it! All of the possible reasons why chameleons open their mouths.
While most tend to fall under typical chameleon behavior, it’s worth knowing what to look out for in case you need to take any additional steps.
Can you tell which one of these is causing your chameleon to open their mouth?
