Do Tarantulas Have 10 Legs?

One common question asked about tarantulas is whether they have 10 legs. It seems a lot of these searches recently are coming from Animal Crossing players, who have noticed that the tarantulas featured there seem to have 10 legs. Why is that? Do tarantulas really have 10 legs? 

If you’ve ever wondered the same thing then read on for the answer!

How Many Legs Do Tarantulas Have?

Tarantulas have 8 legs in total, not 10. That is to say they have 4 pairs of legs in total. 

So what about the other 2?

Well these look very similar to legs, but are infact known as “palps” or “pedipalps” to arachnologists. 

What are Palps?

Do Tarantulas Have 10 Legs?

Pedipalps are the leg-like appendages either side of the tarantula’s mouth – the pair closest to the front of the body. While they look like smaller legs, they are in fact modified mouthparts. 

While tarantulas may use these palps almost like an extra set of legs much of the time, they’re also so much more than this. 

Palps are perhaps most useful to adult male tarantulas. Up until that point the palps look just like the other appendages. However when a male tarantula passes through its final molt and becomes a mature male everything changes. This is sometimes known as the “ultimate molt” of the tarantula. 

In adult male tarantulas these palps suddenly change in appearance. They seem to have what look like tiny boxing gloves on the end. Look closely enough – if you dare – and you’ll see these “gloves” are actually shaped like the stinger of a scorpion. They’re normally kept folded up against the palp so you can’t easily see the shape, but it’s there.

These “gloves” are known as “palpal bulbs”.

It’s no coincidence that they look a bit like a scorpion sting, as they have a similar purpose. They’re actually a mating organ, which is inserted into the female’s reproductive area, and then the sperm is ejected from them. 

How Does the Male Tarantula Use His Palpal Bulbs?

By now you might have realized one weird thing. How is the male tarantula meant to use his palpal bulbs if they’re at the front of his body, while the female’s reproductive area is underneath her abdomen. That doesn’t seem to make a lot of sense. 

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And you’d be right. 

Essentially the male has to grip the female’s front legs and push her up into the air so she’s almost vertical, standing up on her back legs. Holding her there – and bearing in mind she’s quite likely to want to eat him at this point, he then has to move under her, insert his palpal bulbs and, hopefully, escape in one piece at the end. I wouldn’t want to be a male tarantula!

Can Tarantulas Lose Legs?

While we’ve ascertained that tarantulas don’t have 10 legs – they have 8 legs and 2 palps – it’s also important to point out that this is the maximum number of appendages a tarantula may have. 

The reality is that tarantulas can lose legs and they get by just fine. If a predator grabs them by the leg, a tarantula has the ability to drop its leg – like the way a lizard can drop its tail. In this way the predator keeps attacking the now-severed leg, while the tarantula can make a swift escape. 

Another way in which tarantulas can lose legs is when they go through a molt. Let’s remember that in order to molt, the tarantula has to slide out of its old skin. The new skin underneath then slowly hardens over a few days. Sadly, some tarantulas can get caught in their old skin. The new skin can start to harden before they’ve managed to get out of the old one. In these cases, again, it’s better for the tarantula to lose a leg or two but make it out of the molt alive.

So while it’s fair and accurate to say that tarantulas have 8 legs and 2 palps, it is possible to stumble across some tarantulas with less than 8 legs (but never more). This is most commonly seen in wild tarantulas, but can also be seen in some unlucky pet tarantulas. 

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Do Tarantula Legs Grow Back?

The good news is that tarantula legs do grow back over time. The same is true of palps. The next time the tarantula molts you’ll notice it has started to regrow the leg. 

Lost legs rarely regrow to their original size straight away. Instead, the “replacement” leg will be smaller and paler than the original. Then with the next molt it will get larger and more colorful. 

Eventually, after a few molts, you won’t even be able to tell which is the regenerated leg and which ones are the originals. 

So if you see a tarantula that seems to have one leg that is much smaller than the others you can feel confident that it has lost that leg in the past, and is slowly regrowing it. Adult tarantulas typically only molt once a year, so that limb regeneration can take some years to fully complete. 

Richard Adams

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