Spiders around the world consume about 400 to 800 million tons of prey every year — a show of their contribution in keeping ecological balance in check.

According to a team of zoologists from Switzerland’s University of Basel and Sweden’s Lund University, insects and springtails make up more than 90 percent of spider prey. Large tropical spiders also occasionally devour plants and small vertebrates such as lizards, frogs, fish, snakes, birds, and bats.

Spider Diet In Focus

“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. “Spiders thus make an essential contribution to maintaining the ecological balance of nature.”

Spiders are some of the world’s most species-abundant and widespread predators at more than 45,000 species and a population density reaching 1,000 individuals for every square meter (11 square feet). They lead a largely secretive lifestyle of nocturnal activities or camouflaging in vegetation, which previously made it difficult to better illustrate their environmental role and impact.

The team used two calculation techniques based on varying models, finding that the global spider population weighs around 25 million metric tons and wipes out up to 800 million tons of prey annually. Most spiders reside in forests, grasslands, shrublands, croplands, and deserts.

Further calculations revealed that spiders living in forests and grasslands take up more than 95 percent of the yearly prey kill of its global community. This is likely because these areas are less frequently touched by agricultural or urban practices, therefore allowing the biomass to thrive.

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

Last January, a tarantula spider was documented eating a snake under the rock, a rare “dinner” that surprised scientists in Brazil.

Why Spider Predation Matters

Compare this annual prey intake to those of humans and other animals: all humans eat about 400 million tons of meat and fish, while whales feed on up to 500 million tons of seafood. Seabirds, meanwhile, eat approximately 70 million tons of fish as well as other seafood.

The team’s estimates prove important for both natural and semi-natural habitats.

“Many economically important pests and disease vectors breed in those forest and grassland biomes,” added Nyffeler.

Spiders, in turn, serve as an important prey population. Some 8,000 to 10,000 other predators and parasites consume spiders exclusively, while up to 5,000 bird species have made these crawlies a part of their diet.

The findings were discussed in The Science of Nature journal.

Researchers recently discovered three new species of hairy tarantula spiders from the genus Avicularia. These new finds survive in trees and feast on small mammals and birds.

These three species are the A. caei, native only to Brazil; A. lynnae, spotted in Ecuador and Peru; and A. merianae, indigenous to Peru and was named after the naturalist Maria Sibylla Merian. Their genus has grown to include at least 50 species and has been tied to such an imposing size, tree-dwelling ways, and preferred prey of insects, bats, and birds.

In February, experts also revealed that around 40 serious medical conditions including diabetic ulcers, antibiotic-resistant staph infection, and herpes have been and can be mistaken as a bite from a brown recluse spider. Here are ways to tell if it’s a spider bite or not.

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