Read Next

Spiders could eat all the humans on Earth in one year

Just by sheer tonnage of prey consumed, spiders could easily stomach every human on Earth.

Aug 8, 2019 |
5 min read

Before we start, let’s make it perfectly clear that no spider that we’re aware of has declared their intention to do this, or that it is a reasonable target to aim for. No, this is a side maths project for biologists Martin Nyffeler and Klaus Birkhofer, who decided to take a spare moment or two to try to calculate just how much biomass the world’s spider population can actually put away, and what this would mean in human terms.

They published their educated estimates in the journal The Science of Nature and explained that their maths was based on an assumption of a staggering 400-800 million tons of prey being devoured by the world spider population every year.

By comparison, we humans have to make do with eating a meager 400 million tons of meat and fish, annually. Even allowing for all the vegetarians, considering how big the animals we eat actually are compared to the small insects spiders will generally make do with, it does instead make us look like we’re not trying.

And then that brings us to how much biomass we humans represent in the world. Of course, everyone knows we’re outnumbered by tiny invertebrates, not just in numbers but also by sheer tonnage.

But it turns out we only add up to 287 million tons of biomass, little enough that spiders could eat every last one of us in a year and still be left feeling hungry. That’s partly because we are so insanely outnumbered.

While there are north of 7 billion humans on the planet, Earth’s spider population measures in the quadrillions, meaning we are outnumbered by a ratio of 2.8 million to 1. With each human having to be shared equally among nearly 3 million spiders, no wonder there wouldn’t be enough of us to go round, according to Nyffeler and Birkhofer’s estimates.

An article about their findings in the Washington Post has caused quite a stir and even prompted someone to begin a petition to Senator Al Franken via Change.org entitled “Give Spiders All the Help They Need to Eat Every Human on Earth Within One Year.

“It’s reported today by the Washington Post that spiders could eat every human on Earth within one year. We, the undersigned, are certain the spiders are doing the best they can, it’s clear that they could use some help,” the petition organizer, John Darnielle wrote on Change.org, “We call on the United States government to utilize whatever resources it deems necessary and effective to help the spiders in their noble cause. We’re sending our petition to Sen. Al Franken because he’s one of the few people in Washington who we sort of half-trust to not initiate surveillance on us or flag our tax returns for signing such a petition.”

Amongst the comments on the petition are such gems as:

“It’s time we acquiesce to our arachnid overlords. Finally, we will have the World Wide Web we deserve.”, “I’m tired of human beings not being eaten by spiders.”

And the frankly beautiful:

“It’s arachneeded.”

There’s every chance that the petition isn’t entirely in earnest which is just as well since:

  • 1) Al Franken stopped being a Senator in 2018
  • 2) Spiders just don’t eat humans.

For one thing, their tiny fangs are generally only too small to penetrate human skin and, when they do bite us, it’s pretty much always as a defensive mechanism. Or to give us radioactive superpowers. One of the two.

In fact, spiders are far more likely to use those terrifying looking fangs on other spiders, rather than us, potentially even post coitally.

In fact the tendency of female spiders to start chowing down on their sexual partners before the guys have yet finished the job has led to distinctive evolutionary traits and behaviors, such as in the Red Back spider, where the male effectively needs to mate twice, forcing the female to just snack on his superfluous abdomen until he’s done (at which point she draws him in and eats the rest of him).

The males of certain species of funnel weaving spider have even developed the ability to hypnotize their mates into a passive state, just to avoid being eaten by far larger partner.

In prehistoric times spiders could have grown to as large as a meter and a half, a much more human eating kind of size, but sadly not even our more distant hominid ancestors would have been around back then for the spiders to feast on.

Also, if you were thinking that spiders consuming us as we slept would only be our just desserts, considering the sheer number we inhale and swallow as we snore, well it turns out that this is a total myth. In fact, spiders are unlikely to go anywhere near us, or our beds, if they can avoid it.

They do favor bedrooms, as rooms in the house go, but not as high as they value bathrooms, but they still don’t want to get anywhere nearer to a human being than is necessary.

Equally, even those with venomous bites aren’t always as harmful to humans as we might imagine. In fact, some spider venoms are being harnessed for use in medicines for conditions like Alzheimer’s, muscular dystrophy, chronic pain, and even epilepsy.

So, since there are 25 million tons worth of spiders on the planet, who need to eat around 10% of their own body weight every day (so Earth’s spiders are eating 2.5 million tons of prey every day), it’s no surprise that they could take down the whole population before the end of the summer, if they started trying to eat us in January.

But it’s also no surprise, given how teeny tiny their fangs seem and how superabundant more suitably sized prey are, that they just don’t bother.

And I for one thank our arachnid overlords for leaving us well enough alone.

 More great stories to read: 

Read Next: