Why Do Tarantulas Lay on Their Backs?

Many people think that tarantulas lay on their backs to die, but this is not true. Most tarantulas die the right way up, with their legs curled underneath their body. So if tarantulas don’t die on their backs, then why exactly do some tarantulas lay on their backs?

The simple answer is that tarantulas lay on their backs in order to molt. They roll over, split open the old skin, and then slowly slide out of it to reveal a new, larger skin beneath. 

How Long Do Tarantulas Remain on Their Backs?

The process of molting takes some hours, during which time a tarantula may lay on their back. This means that if you see your tarantula laying on it’s back in the evening, typically by the time you wake up the next morning all will be back to normal. The tarantula will have flipped itself back over and should look beautiful thanks to its new skin. 

While it is perfectly normal for tarantulas to lay on their backs in order to molt, they will only spend a very short period of time each year in that position. 

Some tarantulas keepers won’t have seen their tarantula molting in the past; they may simply have just found the discarded skin inside the cage. As a result, finding your tarantula laying on it’s back for the first time can be a surprising and worrying experience. 

Little wonder that so many people end up searching online to try and find out what is going on!

Should You Flip Over a Tarantula Laying on It’s Back?

A tarantula laying on it’s back is in the process of molting. This is a dangerous time for tarantulas. A molt that goes wrong can lead to lost appendages or even death. The less you interfere in the process with the process, the better. 

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If you find your tarantula laying on it’s back it is best to leave the spider well alone.

Do not try to flip the spider over the “right way”, nor disturb the spider in any way. Shining a bright light on the tarantula so you can see better, for example, is best avoided.

The best advice when your tarantula is molting is simply to leave it well alone and let it do it’s thing.

How Often Do Tarantulas Lay On Their Backs?

Tarantulas only lay on their backs to molt. So the question of how often tarantulas lay on their backs is really a question of how often tarantulas molt. 

Adult female tarantulas typically molt once a year, though some species may go for longer stretches between molts. Younger tarantulas molt more frequently. Baby tarantulas – often known as spiderlings – typically molt every few months. As tarantulas grow and get larger, the time between molts normally increases. 

So in answer to the question of how often tarantulas lay on their backs, the answer is likely to be somewhere between every few months and once a year, depending on the size and age of the tarantula. 

Do Arboreal Tarantulas Lay Upside Down to Molt?

It is easy enough for ground-dwelling tarantulas to lay upside down to molt – after all they’ve got plenty of substrate to lay on. But how do arboreal tarantulas moult? Do they lay on their backs too?

Arboreal tarantulas typically build a silken web high up in their cage. In many species this can look like a tiny spider hammock. It is on this hammock that they lay to change their skin. Some arboreal tarantulas will roll onto their backs in order to molt, but others may roll onto their side etc.

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Do All Tarantulas Molt On Their Backs?

While it is very normal for tarantulas to lay on their backs to molt, there are a small number of cases where a tarantula may molt the right way up. Molting the right way up is possible, but it can be slightly more risky. 

All the same, if you find your tarantula molting, but not laying on its back, then this too is reasonably normal, if unusual, behaviour. 

Richard Adams

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