Can A Tarantula Climb A Glass Wall?

Tarantulas are heavy-weighted spiders that are generally rather good climbers. There are even tarantulas that live in trees — also known as arboreal tarantulas. But when you keep tarantulas in a glass terrarium, should you be careful that they don’t climb out? Can tarantulas climb a glass wall of their enclosure?

Tarantulas are able to climb smooth surfaces like a glass wall; even the terrestrial ground-living tarantulas can. However, many tarantulas don’t prefer to climb a glass wall and be mainly with all eight legs on the ground or climb other objects. Because tarantulas can climb on glass, you should always have a lid on your tarantula enclosure.

So, don’t be surprised to see your tarantula climb on glass, but even that they can, doesn’t mean they will climb on it. But, how is a tarantula able to climb on glass with their heavyweight body. How can they get a grip on such a smooth surface?

In this video you can see how easily a tarantula climb a glass wall.

How can a tarantula climb a glass wall?

How do they do it? How can a tarantula with its large body climb on such a smooth surface? Well, there is a secret!

It was long believed that tarantulas grabbed silk from the spinnerets — located on the abdomen — to create lifelines and secure their grip on smooth surfaces. However, a recent discovery shows this is not true.

Tarantulas can climb confidently on glass because of silk-shooting feet. Scientists discovered that tarantulas do not only produce silk in their spinnerets, but also within their eight legs. With the help of small amounts of sticky silk, they can easily climb glass walls — the fibrous silk ‘glues’ to anchor itself down and prevent a fall.

When a tarantula climb on a smooth surface, you will see it always keep four legs on the surface to keep a grip. It also more slowly and more precisely moves its feet.

Tarantulas have more to battle climbing difficult terrain. On each leg, a tarantula has a small claw that helps when climbing. Also, many tiny hairs on their feet — called setules — form a weak electric attraction with the surface to keep them on smooth surfaces. While this attraction work for small spiders and lightweight spiders, tarantulas are too heavy to only rely on this adhesion with the help of setules.

Silk-shooting legs make them able to climb even glass walls. It can even hang upside down because of this adaption.

Read more in this research article about the climbing adaptations in tarantulas.
Fernando Pérez-Miles, Carlos Perafán, Laura Santamaría (2015)

Why is my tarantula climbing walls?

There can be many reasons why tarantulas climb. For arboreal species, it is quite normal that they climb and it would be more surprising and strange to see them on the bottom of their enclosure. For terrestrial tarantulas, however, to see them climb may be a signal that your tarantula wants to tell you something. Let’s discuss the reasons why your tarantula is motivated to climb?

Your tarantula does not like its substrate

Tarantulas that don’t like its substrate may start to climb to get away from it. This can have several reasons. For one is that it doesn’t like the substrate material. This may happen, for example, when you use vermiculite as a substrate.

Another instance when a tarantula climb is when the substrate is too wet. Although tarantulas like humid environments and a damp substrate, when it is too moist, they look for a way they do not get wet feet.

There is mould in the substrate

If the substrate is too dirty, and especially when there is mould growing on it, your tarantula may start to climb. When you see your tarantula effortless try to climb the glass, have a look at the cleanness of your substrate.

Tarantulas are neat creatures. They like a tidy and clean environment. Mould is also harmful to tarantulas, so make sure you keep your enclosure clean and tidy.

There are (pest) creatures in the substrate

An enclosure infested with other (pest) bugs makes your tarantula climb as well. Although cleanup crews in the substrate can be beneficial, your tarantula may not like it crawling under its feet.

Your tarantula may have no problem with other bugs in the enclosure at the start, ut when they reproduce and get with too many, it is trying to avoid them by climbing on objects and possibly also the glass.

Have you seen the substrate guide for tarantulas already? It is packed with practical tips and tricks to create the optimal substrate for tarantulas. Please go check it out!

No suitable place to hide

Terrestrial and fossorial tarantulas like a place to hide. They need a shelter or enough substrate to burrow. If you do not provide this, a tarantula will feel uncomfortable and unhappy. It may also try to search for a place it feels more comfortable and will start climbing objects or the glass walls.

It is important to fulfil the needs of your tarantula. Every tarantula needs some sort of hiding place that suits the species. For fossorial species, you need to provide a thick layer of a substrate. Terrestrial species like to have a wood or bark piece to shelter. Arboreal species like to have pieces of wood to crawl behind to have some privacy.

Your tarantula is exploring its environment

Your tarantulas may climb objects and glass walls simply because it’s exploring the environment. Although tarantulas often are hidden for long times and seem to like sitting still for a whole day, they sometimes go out exploring their enclosure.

Some tarantulas are more curious and more adventurous than others. It depends on the species, but also the character of your individual spider. There are tarantulas that just simply like to climb its terrarium wall.

Your tarantula is hungry or thirsty

When a tarantula is climbing on the terrarium wall can be a sign that your tarantula is hungry or thirsty and search for food or water.

Some tarantulas tempt to climb in the approach of you as a keeper, in the hope they will get their next meal. It can also be learned behaviour. It may be that your spider has learned that, when it climbs on the glass wall or certain object, that it gets food.

A close-up look at one hairy leg of a tarantula where you can see its claw (Photo by Melvyn Yeo)

Why can’t my tarantula climb glass?

By now, it will be clear that a tarantula should easily climb a glass wall or any other slick surface. But it can be that your tarantula will try to climb but fail in the attempt. Don’t worry. There are some logical reasons why it temporarily lost the ability to climb glass.

When a tarantula is nearing its next moult (called premoult), it will often lose the ability to climb slick surfaces like glass walls. The quality of its hairs is not that good anymore. You can recognise that your tarantula is in premoult when it develops a ‘blad spot’ that is shiny and without hairs. Also, often your tarantula starts to get a bit dull coloured when it is nearing its next moult.

It can be that your tarantula has broken its setules hairs on its legs. This may happen when walking on a bad quality substrate or because of excessive climbing (often stress or lack of basic needs). Of course, the first step is to provide the basic needs for your tarantula, so it feels happy again. Do not worry; your tarantula will be able to (better) climb after it is moulted.

Make your tarantula enclosure escape-proof

Now we know your tarantula can climb a glass terrarium wall, you might consider if your enclosure is escape-proof? First, you need to keep your tarantula in an enclosed space. With other words, your enclosure should have a lid on it.

For terrariums, a lid is always included. When you use another type of enclosure, like a glass aquarium, you need to build a lid yourself. Otherwise, your tarantula will walk out in no time. And although you probably are not scared of tarantulas like some people are, you don’t want your tarantula to walk freely in your house. They can harm themselves, and your house has not the optimal environment for them to stay healthy.

However, many terrariums have wired mesh lids on top. There are some tarantulas known to weaken and bend the mesh eventually, and then break out. Also, make sure your tarantula enclosure is closed and locked when you are not around. When a lid is not secured, they can push it open and crawl out.

Want to know more?

Do you like to know more about keeping and caring for tarantulas? If you do check out our basic guide for keeping tarantulas and how to provide the best care for them.

The substrate is one of the most important features in a tarantula enclosure. And there is much to learn about the best substrate for your spider. Read our tarantula substrate guide to learn all about how to provide the best quality substrate, and many practical tips and tricks.

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