Tarantulas can easily climb glass, which means that a secure-fitting lid is essential when they are kept as pets.
They manage this thanks to the microscopic hooks on their “toes”, combined with many fine hairs to be found on their legs.
The ease and speed with which a tarantula climbs glass can vary, however. Arboreal tarantulas have evolved in such a way that they naturally live off the ground. They’re most commonly found resting in or on trees, and may also enter human homes, sometimes found resting up in the rafters waiting for a suitable prey item to pass within pouncing distance.
Such arboreal tarantulas are normally kept in “tall” cages, perhaps with a piece of cork bark arranged vertically in one corner. It is perfectly normal to find the tarantula sat motionless on the side of the tank, effortlessly resting on what should be slippery glass.
While ground-dwelling tarantulas (such as those that burrow or hide under rocks) can climb glass, they tend to be heavier overall. This chunky appearance can make climbing more difficult as well as slower. Even these heavy-set species, however, are capable of climbing glass without too much effort.
In essence, the critical message here for tarantula keepers is that properly sealing the top of your tarantula cage should be considered essential if you are to prevent escape.
Can Tarantulas Climb Plastic?
Most tarantulas can climb plastic just as easily as they climb glass.
Just because you’ve chosen a plastic tank instead of glass, therefore, doesn’t in any way do away with the importance of a close-fitting lid on your tarantula cage.
How Do I Stop My Tarantula Climbing Their Glass?
Many tarantula keepers are concerned when they find their tarantula climbing up the sides of their enclosure. They wonder why it happens (which we’ll get to shortly) and how to stop it happening. Quite frankly, it seems abnormal to some.
There is a greater concern, however. The abdomen of a tarantula is soft and pliable. It is able to rupture if the tarantula falls from enough height, which has been known to cause the death of tarantulas.
Both these reasons mean that many people want their pet tarantula to stop climbing the glass of their cage.
Before we discuss how to stop your tarantula climbing the sides of their cage it’s important to make a clear distinction. This distinction once again goes back to arboreal tarantulas versus other lifestyles.
Arboreal tarantulas can and do naturally climb in nature. They’re slight, with a smaller abdomen and long legs. They can effortlessly climb, even at surprising speed, and will readily chase prey items even on vertical surfaces like the sides of their cage.
Arboreal tarantulas should therefore not be prevented from climbing. It’s just “what they do”.
Preventing terrestrial or fossorial tarantulas from climbing is another matter, however. They do not naturally climb, and spending too much time climbing may pose a health risk to them, especially in taller tanks.
So how do you stop such a tarantula from climbing up the glass? There are several options open to the caring tarantula owner:
Use a Lower Cage
The most obvious way to stop a tarantula climbing the glass of their cage is to move them into a vivarium with less vertical height.
If the space between the top of the substrate and the top of the cage is little more than the legspan of your tarantula then they will have little need to climb.
They’ll be able to reach the top of the cage with one leg, while still having other legs on the ground.
Add More Substrate
An alternative (or additional) tip for stopping a tarantula from climbing the glass is to add more substrate.
The goal is essentially the same; to reduce the distance between the top of the substrate and the lid of the cage. This answer, however, can be cheaper to implement because it removes the need to buy a new cage.
An added benefit of providing more substrate is it can permit more digging for burrowing tarantulas.
Interestingly, once a burrowing (sometimes known as “fossorial”) tarantula has managed to excavate a suitable hole in which to live, they will often naturally stop climbing the glass of their cage.
Improve Cage Conditions
In my experience tarantulas are most likely to climb the glass of their cage in response to environmental conditions. It’s like you or me pulling our chairs a bit closer to the radiator when we’re sitting in a cold room.
So put some thought into your tarantula cage design and be willing to make modifications to see how your tarantula is impacted.
A great example of this would be increasing the temperature in the cage. This prevents the spider from searching high and low for somewhere warmer.
Another would be providing additional or alternative hides (such as pieces of cork bark) so your tarantula has more places to hide.
A third might be swapping the substrate for an alternative; it seems that some tarantulas develop a dislike for walking on certain substrates so a swap can help to reduce climbing in some instances.
An Important Proviso: Tarantulas Are Explorers
It should be noted here that tarantulas are naturally curious animals. It is perfectly normal for a tarantula to wander around its cage from time-to-time, exploring its surroundings.
This is especially so after a tarantula is moved into a new cage.
Just like you or I, they’ll invest some time getting familiar with their surroundings, and deciding where they want to build a lair.
Such temporary glass climbing is not necessarily a worry. It is more when a terrestrial tarantula spends much of their life sitting on the glass that some owners start to get concerned.
Why Is My Tarantula Climbing to the Top of the Tank?
Some tarantulas are less concerned about how to stop their tarantula climbing the glass of their cage, and rather more about why they’re climbing in the first place.
Here are the most common reasons I’ve identified for a tarantula climbing about their cage non-stop:
The first, most obvious reason, is that climbing is simply a natural act among some tarantulas. This is primarily the arboreal species, and when you first put a tarantula into a new cage.
Arboreal tarantulas have evolved to climb, and trying to stop them behaving this way is in direct opposition of how they’ve evolved. Such arboreal tarantulas should be allowed – even encouraged – to climb the sides of their cage.
However assuming your concern is more to do with terrestrial tarantulas then there are other reasons why they may be climbing their cage…
Hungry tarantulas will often go “on the prowl” looking for prey. A tarantula that hasn’t been fed for some time is far more likely to become active in their cage. They may roam the bottom of their cage, and can even climb up the glass sides looking for an insect to grab.
If you repeatedly find your tarantula climbing the glass of their cage then consider when they were last fed, and whether offering a feeder insect will help them to calm down.
Tarantulas are naturally quite shy animals, and appreciate at least one place where they can hide away from view. For ground-dwelling tarantulas this may mean giving enough substrate that they can dig a burrow, or giving them a hide such as a curved piece of cork bark that they can sit under.
Cages that are too “open” and don’t provide hiding places can result in stress. The tarantula responds by seeking out more suitable conditions, and this may include climbing the glass of their vivarium.
Most tarantulas gravitate towards warmer temperatures when given a choice.
In winter, when ambient temperatures are often at their lowest, a tarantula may be seen climbing the sides of their cage in the hunt for additional warmth. In these cases consider adding some supplementary heat so they feel more comfortable.
Searching for a Mate
A mature male tarantula has only one thing on their mind; the search for a mate. Some weeks after their final molt they’ll start this search, which typically only ends in death either through exhaustion or at the fangs of a hungry female.
Mature male tarantulas are therefore typically far more active than juveniles, roaming their cage in search of a mate.
While females are more likely to stay out of view, comfortably resting in their burrow, even they may pace about their cage if they sense an adult male nearby.
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