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Why Do Bearded Dragons Open Their Mouths? 8 Interesting Reasons

Gregory Iacono

By Gregory Iacono

a bearded dragon with the mouth open

As one of the most beloved reptiles kept as pets in the United States, the bearded dragon looks very much like its namesake. With a scaly, armored outer skin, this strangely beautiful reptile includes eight species, but Pogona vitticeps, the Central bearded dragon, is the most popular. The bearded dragon comes from Australia, and their range extends over much of the country. They need a dry, hot environment to thrive. However, bearded dragons have been bred extensively in the United States as pets.

One interesting trait the bearded dragon has is to sit completely still and open its mouth. You might be concerned if your bearded dragon displays this odd-looking habit. In most cases, however, you shouldn’t be. Find out why your bearded dragon sits still and opens its mouth with our list of the eight reasons for this behavior below.

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The 8 Reasons Bearded Dragons Open Their Mouths

1. Your Bearded Dragon Is Engaged in Normal Basking Behavior

Bearded dragons, because they’re cold-blooded, need to raise their body temperature to between 95° and 110° F every day. To help them, most bearded dragon owners place a basking spotlight in their enclosure. The spotlight, which produces moderate heat, allows a bearded dragon to raise its temperature to the correct level.

Once this goal is achieved, most bearded dragons will open their mouth to dissipate any extra body heat they’ve accumulated. This is how they regulate their body temperature, especially since they can’t sweat. In your bearded dragon’s enclosure, it should have an area where it can heat up and cool down. That way, once it reaches its desired body temperature, it can move to a cooler area.

2. Your Bearded Dragon’s Enclosure Is Too Hot

Unfortunately, many bearded dragon owners keep their pet’s enclosure at the wrong temperature, and it’s usually too hot. If you see your bearded dragon with its mouth open (aka gaping), but it’s on the cool side of its enclosure, the temperature is likely too high.

This is especially true if your bearded dragon is hiding and gaping at the same time. A bearded dragon that is acting lethargic is likely overheated and might be dehydrated, also. Before taking it to the veterinarian, you should try letting it soak first. It’s also a good idea to use an infrared thermometer in the enclosure so you can check the temperature easily and regulate it if necessary.

bearded dragon opening its mouth
Image Credit: Incy, Pixabay

3. Your Beardie Is Getting Ready to Shed

Like most reptiles, bearded dragons occasionally shed their skin and beard. Before they do, however, they need to loosen the skin around the area they will shed. To do this, your bearded dragon may sit with its mouth open briefly. Also, some bearded dragons will puff up their beards, which is a great way to stretch them before sloughing them off.

4. Your Bearded Dragon Is Asserting Its Dominance

When you purchased your bearded dragon, you might’ve heard from the breeder that you shouldn’t keep more than one in the same enclosure. They are not social animals; while they may get along for a short time, one will usually try to assert dominance over the other. Opening their mouths is one of the primary methods a bearded dragon will use to establish itself as the “alpha” in the enclosure. This will usually be accompanied by puffing up their beards, and the other bearded dragon, if it’s submissive, will wave its arms.

bearded dragon on the log opening its mouth
Image Credit: Opayaza12, Shutterstock

5. Your Bearded Dragons Are Mating

Although it’s not recommended to keep two bearded dragons in the same enclosure, if you have two in separate enclosures and they can see each other, they may open their mouths during mating season. When it’s time to mate, certain hormones in a bearded dragon’s body are released. These hormones cause it to be a bit more defensive, and keeping its mouth is a defensive measure. Many will also hiss while opening their mouths.

6. Your Bearded Dragon Is Being Defensive

We mentioned that, when mating, a bearded dragon gets more defensive and will open its mouth in a defensive posture. The same thing happens if your bearded dragon feels intimidated or scared. If it does, it will puff up its beard, start hissing, and open its mouth.

This instinct makes a bearded dragon appear larger and more fierce in an attempt to drive away the animal that’s stressing or frightening it. Bearded dragons are also highly territorial reptiles, and even in an enclosure, if they see other animals approaching, they will take a defensive posture and open their mouths.

bearded dragon opening its mouth
Image Credit: Ashley Whitworth, Shutterstock

7. Your Beardie Has a Respiratory Issue

Although relatively uncommon, if the enclosure isn’t ventilated well or is extremely humid, your pet may get a respiratory infection. If this happens, you’ll notice your bearded dragon is gaping for hours at a time. Typically, this occurs with other abnormal behaviors. The good news is that if you catch the condition early, your veterinarian should be able to sort it out, and your beardie will fully recover.

If your bearded dragon’s enclosure gets too cold at night, and then the temperature rises quickly in the morning, it can also cause respiratory issues to emerge. Some of the abnormal behaviors that go along with opening their mouths include the following:

  • Lethargic (slow) movements
  • Coughing and wheezing
  • A loss or lack of appetite
  • Mucus forming around your bearded dragon’s eyes and nose

8. Your Bearded Dragon Has MBD

MBD, which stands for metabolic bone disease, is a health issue your bearded dragon can contract if it isn’t getting sufficient calcium or vitamin D3 in its diet. MBD often occurs with a deficiency in vitamin D due to a lack of UVB lighting in your bearded dragon’s enclosure.

When a bearded dragon has MBD, it will keep its mouth for hours. The condition causes its jaws to swell, and your beardie can’t close its mouth correctly. If your pet displays this behavior, along with the signs below, you must take it to your veterinarian immediately.

  • Its limbs are trembling
  • Your pet has a distinct lack of appetite
  • Its muscles are twitching
  • Your beardie can’t walk
  • Its face or hind legs begin to swell
  • You notice deformities in your pet’s body
a bearded dragon with the mouth open
Image Credit: Dudley Simpson, Shutterstock

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Final Thought

In most cases, a bearded dragon sitting with its mouth agape is 100% normal behavior. Your pet is likely regulating its temperature, but it might be showing aggression towards another bearded dragon (or another pet) or trying to mate with another beardie. An improper diet can also cause metabolic bone disease, and one common sign is the bearded dragon sitting for hours with its mouth open. However, this is uncommon if you feed your bearded dragon the proper diet.

If your bearded dragon is sitting with his mouth open but also showing other unusual behaviors, you should visit your veterinarian to have your pet examined.

Featured Image Credit: Deb Kletch, Shutterstock

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