Spiders Eat 400-800 Million Tons of Insects and Other Prey Annually

It's enough to make an arachnophobia sufferer wince - spiders devour up to 800 million tonnes of prey a year, making them one of the world's most voracious predators, researchers found.

More than 90% of that prey are insects and springtails.

Besides insects, larger species of spiders can also eat frogs, lizards, snakes, fish, birds, and bats.

All the spiders in the world combined annually eat about 440 to 880 million tons of insects and other pests - equal to the weight of more than 85 million elephants, according to a new study.

Nyffeler has been studying spiders for 40 years and used data from 65 previous studies to determine these estimates.

Jumping spider Phidippus mystaceus feeding on a nematoceran prey.

Incredibly, they're capable of killing between 400 million and 800 million tons of prey annually. "Spiders thus make an essential contribution to maintaining the ecological balance of nature", he adds.

The team sourced existing estimates based on biomass averages from a range of different terrestrial biomes - including forests, grasslands, croplands, and other areas - and concluded there's some 25 million tonnes of spiders on Earth right about now.

The stunning numbers comes from a study conducted by scientists from the University of Basel in Switzerland and Lund University in Sweden.

With more than 45,000 species and a population density of up to 1,000 individuals per square metre, spiders are one of the world's most species-rich and widespread groups of predators, the researchers said.

This showed just how big a role spiders play in keeping pests and disease-carriers at bay - especially in forests and grasslands where majority live.

In comparison, spiders in deserts, the Arctic tundra, and annual crops 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.

"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", the study authors wrote. The scientific journal The Science of Nature has published the results.

  • Tracy Ferguson