Wait ... spiders pig out on how much each year?!

"In concert with other insectivorous animals such as ants and birds, they help to reduce the population densities of insects significantly", said lead study author and University of Basel professor Martin Nyffeler in a statement.

It is a long-held belief that spiders are one of the most essential categories of predators of insects, and a recent study has revealed that spiders kill 400 to 800 million tons of insects around the world each year. More than 90% of that prey is insects and springtails (Collembola).

A new study released on Tuesday says that spiders eat an estimated 400 to 800 million metric tons of insects every year.

The researchers estimate that there's probably around 25 million metric tons of spiders in the world.

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.

Nyffeler has been studying spiders for 40 years and used data from 65 previous studies to determine these estimates. "Spiders thus make an essential contribution to maintaining the ecological balance of nature", he adds. Furthermore, large tropical spiders occasionally prey on small vertebrates (frogs, lizards, snakes, fish, birds, and bats) or feed on plants.

It's hard to estimate the number of spiders in the world.

The vast majority of this insect devouring occurs in forests and grasslands, which are thought to account for about 95 percent of the annual spider prey kill. These eight-legged creeps have a population density of up to 1,000 individuals per square meter. They thrive in forests and grasslands, killing much more prey than in deserts and agricultural areas, the study found.

As a result of most spiders' clandestine lifestyle, it has been challenging to show their ecological role.

"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. Spiders are also an important source of food for 8,000 species of birds, parasites and other predators.

The findings are reported in The Science of Nature.

  • Joey Payne