Spiders eat astronomical numbers of insects

Spiders eat astronomical numbers of insects

The study team also revealed spiders kill a lot more insects in forests and savanna than in other environments.

More than 90 percent of the spider diet is made up of insects and insect-like springtails, and by devouring several hundred million tonnes of these tiny pests every year, researchers say spiders play an essential role in keeping natural ecosystems in check. In addition to eating insects, big, tropical spiders will also prey on small vertebrates like frogs and fish from time to time, or eat plants.

A gargantuan figure at least equivalent to the quantities of meat and fish consumed each year by humans (400 million tons), according to data from the Food and Agriculture Organization of the United Nations ( FAO ).

"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.

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.

Each year spiders eat an estimated 400 to 800 million metric tons of insects. They make an important contribution to maintaining the planet's ecological balance. 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.

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

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.

The appetite of spiders even exceeds that of whales, which get through an estimated 280 million to 500 million tons of prey a year.

But if you're now worrying that the world might be inherited by spiders, remember that in turn, they are a source of prey as well. Between 8,000 to 10,000 predators eat only spiders, and another 3,000 to 5,000 bird species eat them frequently, USA Today reported.

The study appeared online Tuesday in the journal The Science of Nature.



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