Now and again you might come across a living spider with 6 legs. Does this mean they were born this way? Do some spiders only have 6 legs? The simple answer is no…
Spiders are all born with eight legs. If you see a spider with 6 legs, then it means that they have lost two somewhere along the way. Many spiders can cope with this, and continue to lead healthy lives. Sometimes their missing legs could partly regrow.
While that’s sad, it’s also interesting to look at how a spider is able to cope with 6 legs, and let’s also answer the question as to whether or not they can grow a leg back.
There is a whole lot more to this issue of a spider and its legs than you may imagine. So, let’s check it all out.
To Be a Spider, It Must Have 8 Legs
Let’s get one thing absolutely straight, in order to qualify as a spider, it must have 8 legs when born.
Like we just said, it is possible that a spider will lose a leg at some point in its life, but it was still born with 8 legs. That simple fact cannot be disputed in any way. If a creature is born with 6 legs, then it’s not a spider.
Well, it turns out that there may very well be an explanation for it, and it’s all to do with their ancestors. Note, this is one theory that’s out there, but it’s not the only one.
A spider has evolved from the same ancestor as a horseshoe crab.
If you look at this crab, it actually has 12 limbs, and that’s a lot. [Source] So, it makes sense that a spider has this many legs simply because of where it comes from. Just imagine what it would have been like if the spider had 12 legs!
Also, it’s common for a spider to lose a leg.
There are some ideas that the percentage may be as high as 30%, and that’s astonishing.
However, other studies put it as low as 5%, but considering the huge number of spiders out there in the world, that’s still a lot without a leg.
Another Theory About 8 Legs
But there’s another interesting theory about why a spider has 8 legs, and it’s to do with nature providing them with a couple of extra ones. That may sound strange, but it’s grounded in some sense of reality.
Scientists have studied spiders that have lost a couple of legs in their life, and they have discovered that those spiders are just as good at doing things as those with a full quota.
A spider with only 6 legs can still make the same web, mate, and catch the same prey as one with 8, so it appears to be the case that the spider is not inhibited in any way if it’s missing a leg or two.
But the problem comes when they go below 6 legs. Life becomes a lot harder for them at that point, and then the life of the spider is going to be in danger.
So, the theory is that they were given a couple of extra ones just in case of a mishap to make sure that they could still survive.
The difficulty we have is that spiders have been on the earth for around 400 million years.
There’s an argument that the environment shaped everything, but we don’t know the exact kind of environment the spider was living in all those years ago. Something in there must have made it important that the spider had so many legs.
So, this then opens up the question of how a spider can lose a leg, or two?
Escaping From a Predator
This is one of the coolest things about a spider, and it’s the way in which they can escape from a predator by basically giving up a leg. If a spider has been caught by a predator, they can release a leg in order to get away. It seems like a small sacrifice to make in order to survive and not merely be eaten.
It’s tough for us to imagine what it must be like to have to do this, but it’s second nature to a spider. They would prefer this to happen compared to the alternative situation.
Once again, this fits into the theory of a spider being born with a couple of extra legs.
Us Catching Them the Wrong Way
All of those spider catching gadgets can unfortunately hurt a spider who was just busy going about their own lives before we decided to interrupt them.
A number of the gadgets to catch a spider can sadly lead to the spider losing a leg if it’s not used in the correct way.
It’s not our intention, but a leg can be caught, and the spider, which is highly stressed and anxious, will basically do the same as they would if caught by a predator.
That means the leg comes off to hopefully allow them to escape.
The idea of being able to shed a body part to get away is astonishing, but it’s not the only party trick that a spider is going to have up its sleeve.
How a Spider Copes
So, how is a spider able to cope with the fact they have lost 1 or 2 legs? Well, it doesn’t affect their ability to do anything at all, so the initial answer is that they cope pretty well with their new situation.
One thing to remember is that a spider will generally lose a leg at a specific break point. These points are important, as it does mean their abdomen is protected.
This entire thing is well calculated by the spider, and while we may see it as a stressful event, they appear to be capable of getting over things pretty quickly and moving on with their life.
A spider is also likely to feel some pain when they lose a leg, but we don’t believe that it’s to the same extent as we would experience. However, that is something that is always up for debate, but they are certainly aware that something has happened to their body.
The one thing we do know is that the spider will get back to its old ways pretty quickly. Even losing a leg won’t stop them from building a fantastic web in order to catch their prey.
They Could Regrow Their Leg
So, let’s say the spider has lost a leg, how cool is the fact that they can regrow that leg and be back to normal? Well, that’s what can happen, but there must be certain circumstances for it to occur.
For example, they can only regrow the leg if they have a molt cycle left, or more than one in some cases, as it’s the molting aspect that will allow them to refashion a new leg.
Remember that your spider has an exoskeleton, so they need to molt in order to grow and become an adult spider. If they have a molting cycle left, then this new leg will appear. [Source]
However, the new leg doesn’t come back the exact same as the other 7. Instead, it tends to be somewhat shorter and also thinner than the other legs.
The amazing thing is that the spider doesn’t allow this to hold it back as you must remember that it can easily survive with 6 legs without it having a negative impact, so this ability to regrow a leg is not always necessary.
Of course, even if they are past that last molt cycle, they can still survive perfectly fine without the leg, so don’t stess if you see a spider with a leg or 2 missing. They are quite content.
Just to Recap
So, a quick recap in order to clear everything up. Yes, a spider can indeed have 6 legs, but it’s only due to some kind of trauma and is not the way they were born.
At times, it’s the spider itself that gets rid of a leg in order to survive, and we think that’s a cool thing to happen. Add in the fact that some spiders can effectively regrow a leg, in the right circumstances, and what you have here is an amazing creature that gets something of a bad press.