Spiders are beneficial in keeping insect populations down and also protect plants and trees that could be food for invasive insects, study lead author Martin Nyffeler of the University of Basel in Switzerland said.
According to their extrapolations, 400 to 800 million tons of prey are being killed by spiders each year.
The researchers estimate that there's probably around 25 million metric tons of spiders in the world.
The appetite of spiders even exceeds that of whales, which consume an estimated 280 million to 500 million tons of prey a year. Their conclusion: altogether there are about 25 million metric tons' worth of them around.
Spiders, in turn, serve as an important prey population. They make an important contribution to maintaining the planet's ecological balance.
Among the astronomical amount of prey, insects and springtails remain the top snack for the spiders, accounting for over 90 percent of their annual prey consumption, Other spiders, especially large tropical spiders, sometimes feast on small vertebrates, such as snakes, frogs, lizards, bats and fishes. Spiders have been found in the northern most islands of the Arctic, the hottest deserts, at the highest altitudes of any living organisms, bogs, sand dunes and other types of habitats. Zoologists at the University of Basel and Lund University in Sweden have now shown just how true this is - spiders kill astronomical numbers of insects on a global scale.
With the new findings, it will help future researchers to calculate how spiders eating (and being eaten) contribute to the global food chain, while also shining the spotlight on how necessary these eight-legged critters really are.
"We hope that these estimates and their significant magnitude raise public awareness and increase the level of appreciation for the important global role of spiders in terrestrial food webs", Dr. Nyffeler said. Between 8,000 and 10,000 other predators, parasitoids and parasites feed exclusively on spiders, while spiders at the same time form an important part of the diet of an estimated 3,000 to 5,000 bird species. The scientific journal The Science of Nature has published the results.