There are a more spiders on earth than most people would dare to imagine. In fact, the world’s spider population weighs in at a whopping 29 million tons, or roughly the equivalent of 478 Titanics. As horrible as that seems, there is another fact about spiders that is even more terrifying — They’re everywhere!
A study was done recently in North Carolina where a physical inspection of 50 different houses conducted by entomologists discovered spiders in 100% of the homes and it wasn’t just in basements or attics either. Of these homes, 68% had spiders in the bathroom, 78% had them in bedrooms and 90% had spiders in the kitchen. There is a decent chance you have crossed paths with a spider in your own home today, whether you realized it or not.
Most spiders only eat insects, but that doesn’t make them any less terrifying. Then there are some of the larger species that also eat lizards, rodents, small mammals and even birds. Knowing this made two European biologists, Martin Nyffeler and Klaus Birkhofer, curious; What is the sum total eaten in 12 months by the world’s spider population?
Their results, published in the journal The Science of Nature earlier in the month, concluded that somewhere between 400 million and 800 million tons of prey are consumed by spiders each year. That is a hard number to visualize so to put it in perspective for even the most basic of laymen, the total biomass of the earth’s human population of 7 billion people equates to around 287 million tons.
What that means is that spiders could eat every man, woman, and child on earth in 12 months and still have plenty of room left for dessert. What is even more frightening is the fact that humans consume about 400 million tons of meat and fish per annum. Yes, spiders eat more prey when measured in total mass per year than humans do.
The researchers did some complex mathematics based on estimates to arrive at this total. First they had to figure out how many spiders live in a square yard for all of the main habitat types on earth as well as the average amount of food consumed by spiders of different sizes in a 12-month period. If you weren’t arachnophobic before you read the results, there’s a good chance you are now.