Crested Gecko

7 Reasons A Crested Gecko Is Opening Its Mouth Wide

Geckos are well-known for their ability to climb walls and cling to ceilings, but did you know that they can also open their mouths extremely wide? If you’ve ever seen your crested gecko open its mouth really wide, you may be wondering why it’s doing this.

Why Do Crested Geckos Open Their Mouths Wide?

Here are the reasons why crested geckos open their mouths wide:

  • Body temperature regulation
  • Respiratory infection
  • On guard ready to fight or defend itself
  • Possible metabolic bone disease
  • High tank temperature
  • Low tank humidity
  • They are yawning

If you see your gecko opening its mouth frequently and you’re not sure why this article will help.

Body Temperature Regulation

When a reptile is too warm, it will open its mouth and extend its tongue to promote heat loss from evaporation. The crest on a Crested Gecko’s head also plays an important role in regulating its body temperature. By cupping their hands over their crests, they are able to direct heat away from their bodies and help them stay cool.

In addition, Crested Geckos will often move to different areas of their enclosure to regulate their temperature. If they are feeling too warm, they will move to a cooler spot. Conversely, if they are feeling too cold, they will move to a warmer spot. By carefully monitoring their environment and adjusting their position accordingly, Crested Geckos are able to maintain a comfortable body temperature.

Respiratory Infection

If you see your Crested Gecko opening its mouth and appearing to gasp for breath, it could be a sign of a respiratory infection. These infections are caused by bacteria or viruses and can be serious if left untreated. Early signs of a respiratory infection include lethargy, loss of appetite, and increased mucus production.

If you notice any of these symptoms, take your gecko to the vet for a check-up. Respiratory infections can be treated with antibiotics, but it’s important to catch them early. 

On Guard Ready To Defend

When a crested gecko opens its mouth and bares its teeth, it may be trying to look bigger and scarier in order to defend itself. If you see a crested gecko doing this, it’s best to leave it alone and give it some space. Crested geckos are usually gentle creatures, but they can get scared or upset just like any other animal.

When they feel threatened, they may open their mouths wide in an attempt to make themselves look more intimidating. In the wild, this behavior may help to scare off predators or competitors.

However, in captivity, there is usually no need for such displays of aggression. If you see a crested gecko opening its mouth, try to figure out what might be causing the stress and see if there is anything you can do to help make the situation better.

Possible Metabolic Bone Disease

If your Crested Gecko is frequently opening its mouth, it could be a sign of Possible Metabolic Bone Disease. This is a serious condition that results from a lack of nutrients, especially calcium and vitamin D3. Without these essential nutrients, the bones can become weak and deformed.

Symptoms of Metabolic Bone Disease include softening of the jawbone, malformed bones, and muscle weakness. If you think your Crested Gecko may have this disease, take it to the vet for diagnosis and treatment. Left untreated, Possible Metabolic Bone Disease can be fatal.

High Tank Temperature

It turns out that there are a few reasons why the temperature in the tank could be the cause. If the temperature is too hot, the gecko will open its mouth to pant and cool down.

The downside to this is that if the temperature gets too high, it can actually start to cook the gecko from the inside out. If the temperature is too cold, the gecko will open its mouth to warm up.

Low Tank Humidity

Another reason why your gecko might be opening its mouth is due to humidity levels. If the humidity in the tank is too low, the gecko may open its mouth to try to increase the humidity level.

One way to tell if this is the case is by checking for mucous around your gecko’s nose. If you see any, it’s an indication that the air is too dry. By increasing the humidity levels, you can help your gecko stay healthy and comfortable.

They Are Yawning

Some people believe that crested geckos open their mouths when they yawn, but this is not the case. When a crested gecko yawns, its mouth opens wide and its tongue extends outwards.

The skin around the mouth does not open up like it does when the lizard is gliding. Instead, the skin stays in place and the crest simply flattens out. So, if you see a crested gecko with its mouth open, it is not yawning; it is probably getting ready to glide!


If your crested gecko is continually opening its mouth, it could be due to a variety of different reasons. It might be trying to catch some prey, or checking out its surroundings. If you notice your gecko doing this more frequently than usual, it might be a sign that it’s not feeling well.

However, if your gecko seems healthy and active otherwise, then there’s a good chance that its mouth-opening behavior is simply due to curiosity.


Chris is a reptile enthusiast, breeder, and blogger from the Milwaukee, WI area. After breeding hundreds of bearded dragons to supply local pet stores and owning many other types of reptiles, he is now focused on sharing knowledge to help owners properly care for their little reptiles friends.

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