Spiders could theoretically eat every human on earth in one year


Love is, actually, all around us. Coincidentally, so are spiders.

An entomological survey of North Carolina homes turned up spiders in 100 percent of them. More specifically, 68 percent of bathrooms and more than 75 percent of bedrooms.

Luckily, spiders eat mostly insects -- especially the ones you may also find in your home. But as spiders get bigger, so do their prey, and larger arachnids feast on lizards, birds and small mammals.

The appetite of the tiny beasts had two European biologists wondering: How much food does the entire spider population eat in a single year?

Martin Nyffeler and Klaus Birkhofer published their estimate in the journal the Science of Nature in early March. They found that all the spiders in the world consume somewhere between 400 million and 800 million tons of prey in any given year.

That's pretty disturbing. But what's even more disturbing? The amount of "meat" is equivalent to that of all 7 billion humans on the planet combined.

Spiders could, theoretically, eat every single human on earth within one year.

It gets worse. Those humans consume about 400 million tons of meat and fish each year, so ultimately, the tiny creatures are consuming all of that, too.

Does this seem like a stretch? The biologists provided another way to look at it.

The total biomass (which is the total mass of organisms in a given area or volume) of all adult humans on earth is estimated to be 287 million tons. And yes, spiders could eat all of that.

Even if you consider an extra 70 million tons to account for the biomass of children, it's still not equal to what spiders can consume.

So, technically and theoretically, the total amount of food consumed by spiders in one year exceeds the total weight of the entire population of the globe. Spiders could eat all of us and still crave more.

Let's break it down.

Nyffler and Birkhofer's calculations are complicated. The estimations are based on research into how many spiders live on a square meter of land for all main habitat types of earth, and the average amount of food consumed by spiders of different sizes in one year.

Those numbers are too interesting to glaze over. One study estimates that the global average spider density is 131 spiders per square meter.

Obviously, habitats like deserts have fewer spiders, but others have spider densities of 1,000 per square meter. (The scientists did not describe those densely populated areas of spiders, but we assume it's either in a forest or in the corners of your room.)

If you weighed every single spider on earth, they'd weigh about 25 million tons, according to Nyffler and Birkhofer.

A handy infographic from The Washington Post shows that the Titanic weighed about 52,000 tons. So the mass of every spider on earth is equivalent to 478 Titanics.

So, moving on, spiders consume about 10 percent of their body weight per day. (If you weigh 200 pounds, imagine eating 20 pounds of meat daily. It's a lot.)

According to that calculation, it would take approximately 2,000 pounds of spiders to consume a 200-pound man in one day.

Keep in mind this is probably never going to happen. Spiders are never going to revolt and feast on the entire human population.

Good news! Their voracious appetites are actually good for humans -- they keep mosquitoes and other pests away from your homes and yards. Who knows how many people mosquitoes could eat in a year.

[H/T The Washington Post]