Spiders, in turn, serve as an important prey population.
Using data from 65 previous studies, Nyffeler and Birkhofer first estimated how many spiders are now to be found in seven biomes on the planet.
It is news that no arachnophobe will wish to hear - but spiders are one of the world's most voracious predators after devouring a whopping 800 million tons of prey each year.
After extrapolating and calculating and estimating, they came up with the "400 to 800 million tons of prey are being killed by spiders each year" figure. About 90% of their prey consists of springtails, insects, and other arthropods. Furthermore, large tropical spiders occasionally prey on small vertebrates (frogs, lizards, snakes, fish, birds, and bats) or feed on plants. "Spiders make an essential contribution to maintaining the ecological balance of nature", Nyffeler said, USA Today reported.
"There is hardly any terrestrial area on this globe where spiders would be missing", wrote the researchers, Martin Nyffeler of the University of Basel and Klaus Birkhofer of Lund University in Sweden and the Brandenburg University of Technology Cottbus-Senftenberg in Germany.
I can't even conceive of what a single pound of spiders would look like, let alone 25 million metric tons of them. Spiders in these locations catch enormous numbers of forest and grassland pests, while spiders living in deserts, Arctic tundra and agricultural areas kill fewer insects.
Humans consume about half that amount, eating 400 million tonnes of meat and fish, while whales get through an estimated 280 million to 500 million tonnes.
In comparison, all the humans on Earth consumed about 400 million tons of meat and fish each year, according to the UN Food and Agriculture Organisation. These eight-legged creeps have a population density of up to 1,000 individuals per square meter.
As a result of most spiders' clandestine lifestyle, it has been challenging to show their ecological role.
Of course, spiders are just part of the food chain, and are frequently eaten themselves: Between 8,000 and 10,000 predators feed exclusively on spiders, while spiders are also an important part of the diet of an estimated 3,000 to 5,000 bird species.
"We hope that these estimates and their magnitude will help alert public opinion and improve the overall appreciation of the role of spiders."".
The study appeared online Tuesday in the journal The Science of Nature.