Spiders ― those eight-legged, hairy, creepy-crawling, poison-fanged, silk-spinning arachnids ― are often the stuff that nightmares and horror movies are made of.
Spiders primarily eat insects, with the exception of some larger spider species that have hearty appetites for a good lizard or bird or small mammal. But Washington Post reporter Christopher Ingraham explored a disturbingly intriguing dilemma this week ― if spiders ate human beings, how many would they eat?
The matter came up because earlier this month, European biologists Martin Nyffeler and Klaus Birkhofer published a paper in the journal Science of Nature, estimating the total weight of prey consumed by spiders as a group.
Their assessment: “Spiders evolved around 400 million years ago and are among the most common and abundant predators in terrestrial ecosystems. The annual prey kill of the global spider community is in the range of between 400 and 800 million metric tons.”
As the Post points out, the weight of what spiders eat in one year is more than all humans on the planet combined, citing a 2012 study that estimates the total biomass of all adults on Earth as about 287 million tons.
“Even if you tack on another 70 million-ish tons to account for the weight of kids, it’s still not equal to the total amount of food eaten by spiders in a given year, exceeding the total weight of humanity,” Ingraham writes.
The ominous conclusion (and possible scenario of a future end-of-humankind movie thriller) is that spiders have the potential of eating every one of us and not feeling full after the meal.
And there’s nowhere on Earth you’d be safe from this hypothetical human-eating spider chowdown, either.
There are currently approximately 45,000 species of spiders that “exhibit a very diverse range of lifestyles and foraging behaviors,” the scientists write. “Some spiders can travel distances of up to 30 km in a single day. There is hardly any terrestrial area on this globe where spiders would be missing.”
And while we’re on the topic of spiders eating humans and vice versa ― the long-standing myth that humans eat up to eight spiders a year while we sleep isn’t really true. Bill Shear, former president of the American Arachnological Society, told Scientific American last year that spiders have little interest in humans one way or the other. “We’re so large that we’re really just part of the landscape.”
And based on these latest calculations, we’re grateful for that.