Spiders are creepy to some people! One of the main reasons people tend to be creeped out by spiders is because of their 8 legs – which are sometimes really hairy and long.
But if you are not one of those people that get creeped out by spider legs, you may be interested in learning why spiders have eight legs.
This article breaks down the reasons spiders have eight legs and presents a study that possibly confirms that spiders don’t really need eight legs.
In the study discussed in this article, you will learn how spiders that don’t have eight legs are still able to survive and perform activities that spiders with eight legs can perform, like building webs and catching prey.
Let’s get started learning about spiders and their legs!
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Do All Spiders Have 8 Legs?
All spiders are born with 8 legs as a part of their anatomy unless there is some sort of birth defect that happens – but naturally – all spiders have eight legs.
However, it is not uncommon to find a spider that has less than 8 legs due to other reasons in nature.The cause for this is that some spiders may lose a leg or two for unnatural reasons.
Spiders that only have 6 or 7 legs, likely lost a leg or two while escaping a predator or for another similar reason like getting caught in your door or window frame when you close it.
Spiders typically have two pairs of front legs and two pairs of back legs all attached to their cephalothorax.
Although the placement of the legs can vary from species to species, all spiders have eight legs to start their lives with.
Do Spiders Need 8 Legs?
A study conducted by scientists found that after collecting thousands of spiders from the wild, over ten percent of them were missing at least one of their eight legs.
Since over ten percent were missing legs, scientists wondered if this caused the spiders to be less effective than spiders that still had their eight legs.
Scientists placed over one hundred spiders in individual boxes where the spiders would be able to still build their webs.
Around half of the spiders placed in the boxes were missing at least one leg.
Scientists found that even though half the spiders were missing at least one leg, their webs did not differ significantly from the spiders that still had eight legs.
They also found that spiders only missing one or two legs were still effective hunters and were still very capable of catching and eating prey.
However, there was a limit to how effective spiders can be when missing some of their legs.
The study also found that spiders missing more than two legs were only able to build shoddy webs and weren’t as effective as spiders only missing one or two legs.
Although on a small scale, this proved that spiders that are missing one or two of their eight legs can still be effective at building webs and don’t differ that much from spiders that still had all their eight legs intact.
It is important to note that in this study, scientists did not find many spiders in the wild that were missing more than two legs, so it seems that if they are missing more than two legs, they don’t have much chance of survival in the wild.
Why Do Spiders Have 8 Legs?
Since the study conducted by scientists proved that spiders don’t necessarily need eight legs, you might be wondering why spiders even have eight legs in the first place since it doesn’t appear as though they need so many legs.
It is believed that the reason spiders have 8 legs is that the extra legs can actually save their lives.
Spiders with less than eight legs most likely lost one of their legs due to a predator or in a fight with another spider.
Scientists propose that spiders have eight legs – which is more than they need – so that if they are caught by predators, they are still able to get away by losing a leg or two.
If a predator has latched onto one of their legs or bitten a leg off, they can afford to lose that leg and still get away and survive.
Spiders may even sever one of their own legs if doing so will help them escape a predator.
This is an advantage for the spider because even though they’ve lost a leg or two, they are still able to function similarly to spiders that still have their eight legs.
They are still able to effectively hunt and successfully build webs just like spiders that have eight legs.
So they are able to live another day by losing a leg or two and it doesn’t affect them too much.
Do Spider Legs Grow Back?
Spiders can typically regrow their lost legs if they have at least one more molt left in their life cycle.
However, this isn’t the case with all spiders but the odds of being able to regrow legs go up with the more molting periods a spider has left in its life.
If a spider is older and has no more molts, the spider will not be able to regrow a lost limb.
How Long Does It Take for Spider Legs to Grow Back?
The length of time it takes a spider to regrow a leg depends on how long the spider molts. Most younger spiders molt around once a month while older spiders may not molt but once every year or so.
Some spiders have a molt that will only last a few days up to a week while others can last several weeks in the molting process.
If a spider is regenerating a leg during molting, the molting process will be extended by at least a few days in most cases to account for the regrowth of the lost limb.
Can All Spiders Regrow Legs?
No, not all spiders have the ability to regrow their legs. Spiders have a better chance of regenerating a lost limb if they are younger and have several molts left.
However, once the molting is limited as they get older, they are unlikely to be able to regrow a lost leg.
Even in younger spiders, there is no guarantee that molting will produce a new leg – and oftentimes – it may take several molts to fully regenerate a lost leg to its full capacity and strength.
Do Spiders Eat Their Own Legs?
Spiders don’t eat their legs if they are still attached to them.
But some spiders (such as tarantulas) will eat legs that have become severed from their body – assuming it wasn’t a predator doing the severing.
If a spider lost a leg for some other reason that didn’t involve a predator, there is a good chance that it will eat the severed limb.
Scientists believe this may be a way for spiders to recycle the lost proteins.
10 Common Questions Related to Spider Legs
Below are ten common questions about spiders and their legs.
1. Do All Arachnids Have 8 Legs?
Almost all adult arachnids such as camel spiders, harvestmen, mites, scorpions, spiders, ticks, and whip spiders have 8 legs.
Although some arachnid species have evolved to start using their front pair of legs as sensory limbs.
2. Are There Any Two-Legged Spiders?
There are no known species of spiders that are born with only two legs as this would be impossible for them to survive in the wild since their mobility would be limited and they would be extremely vulnerable to predators.
3. Are There Any Four-Legged Spiders?
As with two legs, there are no spiders that are born with only four legs and there are none that have been observed in the wild with only four legs.
Some spiders have been found with only five legs in the wild, but that seems to be the limit for a spider to survive.
Since these spiders aren’t born with just five legs, they most likely lost their other legs due to predators.
Although some spiders were found in the wild with only 5 legs, the loss of three legs appears to have hindered those spiders’ abilities to successfully hunt and build strong and sturdy webs.
It is unlikely that a spider with five legs or less would survive very long in the wild because the loss of that many limbs hinders their abilities to move quickly and makes them easy targets for predators since it would be hard for them to evade predators with only five legs (or less).
4. Are There Any Six-Legged Spiders?
While spiders have been found in the wild with only six legs, this isn’t a natural occurrence and is likely due to a predator biting off their other legs.
Any spider that has less than eight legs (whether it is a five-legged, six-legged, or seven-legged spider) is considered unnatural and will always have a valid reason, such as predators or possibly birth defects.
5. Are There Any Ten-Legged Spiders?
Ten-legged spiders are a hot debate in the science world.
While spiders really only have eight legs, some may consider their pedipalps – which are arm-like or short leg-like appendages on their cephalothorax – to be an extra set of legs, which would give a spider ten legs.
However, this is a highly debatable topic and it isn’t widely accepted in the science community that spiders actually have ten legs – especially considering that pedipalps are much shorter than the eight legs that spiders have surrounding their body.
6. Do Tarantulas Have Eight Legs?
Just like all other species of spiders, tarantulas have eight legs. If you happen upon a tarantula that has less than 8 legs, this is not natural and the tarantula has lost a leg or two due to a fight or due to a predator.
7. What Kind of Legs Do Spiders Have?
While spiders have muscles in their legs to flex them inward, they don’t have muscles to extend their legs outwards.
Spiders have hydraulic pressure in their legs that help them to extend their legs outward.
This is what causes spiders to have more of a jerky movement pattern that creeps many people out.
This is also why spiders curl up when they die.
Since spiders don’t have muscles to extend their legs – when they die – their legs curl up because the hydraulic pressure no longer forces their legs to extend outward.
8. How Do Spider Legs Work?
Spiders use muscle flexing to bring their legs inward and hydraulic pressure to extend their legs outward.
When moving, spiders use their front two pairs of legs to flex inward, causing a pulling force.
The third pair of legs are used as a pivot point while the fourth pair of legs extend from the hydraulic pressure, creating a pushing force.
This is how a spider walks and creates that jerky movement that most humans hate the sight of.
9. Do All Spiders Have Hairy Legs?
No, not all spiders are equipped with hairy legs or hair on their bodies at all – for that matter.
Some of the hairiest spiders are tarantulas, but other spiders such as black widows have little to no hair at all on their bodies – making them hairless spiders.
10. Do Spiders Have Arms?
While they are not specifically called arms, spiders do have a pair of pedipalps on their cephalothorax that are used somewhat in a similar manner as arms – although most scientists still consider them to be “leg-like” appendages.
Pedipalps help spiders shape their webs, sense objects that are encountered by them, and assist spiders in capturing and feeding on prey.
Recap
Thank you for checking out this article about spider legs.
In this article, you learned that all spiders have eight legs unless they lost legs due to fighting, a predator, or because of some other unnatural reason.
You should now know that spiders can survive with less than eight legs and some can even regrow their lost limbs if they are younger and still able to go through the molting process.
You learned how spiders use their legs and why some of them may be missing their legs in the first place.
So if you see a six-legged spider in the wild, you now know that this isn’t a natural occurrence and was likely due to one of the reasons mentioned above.
But don’t feel sorry for a six-legged or seven-legged spider since they are still able to live a normal life and do everything an eight-legged spider can do.
That is all I have to say about spider legs, but honestly, that was a lot!
If you enjoyed this article about spider legs, you are sure to find more enjoyable articles in our “spider parts” section where you can learn more about spider anatomy and how various spider parts work.
