A study by two biologists reveals that the number of arachnids on Earth and their eating habits far exceed humanity, since if you combine all types of spiders, they could eat all humans on the planet in a year (in theory...).
Spiders are literally all around us. There's a good chance that at this very moment at least one spider is hiding in a dark corner of the room you're in. If you've already stopped looking around, keep reading because what follows will make your hair stand on end. As is well known, spiders mostly eat insects, although some of the larger species bite lizards, birds, and even small mammals. Given their abundance and the voraciousness of their appetites, two European biologists asked themselves: if you had to count all the food consumed by the world's spider population in a single year, how much would it be?
Martin Nyffeler and Klaus Birkhofer published their estimate in the journal Science of Nature, and the number they arrived at is frankly surprising: spiders eat the equivalent of between 400 and 800 million tons, among their different types of prey, in a year. That means spiders eat at least as much meat as the 7 billion humans that inhabit the planet. For a slightly more unsettling comparison: the total biomass of all adult humans on Earth is estimated at 287 million tons. Even if you add another 70 million tons to account for the weight of children, it still doesn't equal the total amount of food spiders consume in a given year, exceeding the total weight of humanity. In other words, spiders could eat all humans on Earth in a year and still be hungry.
To arrive at this number, Nyffeler and Birkhofer made a very sophisticated estimation based on existing research on how many spiders live in a square meter of land for all major habitat types on Earth, and the average amount of food consumed by spiders of different sizes in a given year. The biologists have also discovered that spiders consume approximately 10% of their body weight in food per day. But in the end, the voraciousness of spiders actually works to humanity's benefit, since they primarily feed on insects, which means fewer pests in the garden, and fewer mosquitoes and flies in your home.
Source: Springer.
