As if their venomous fangs, hairy legs and unholy sex routines weren’t enough to contend with, scientists have now revealed yet another reason to fear spiders: a voracious appetite that dwarfs even our own.
Earth’s arachnids devour 400 to 800 million tonnes of prey each year, according to a new study which establishes their critical role in the insect food chain.
By comparison, humans consume 400 million tonnes of meat and fish every 12 months, and whales an estimated 280-500 million tonnes of prey.
“Our calculations let us quantify for the first time on a global scale that spiders are major natural enemies of insects,” said Martin Nyffeler from the University of Basel, lead author of the study.
While the 25 million tonne global spider population feasts mostly on insects and springtails, larger arachnids also eat frogs, lizards, snakes, fish, birds and bats.
“In concert with other insectivorous animals such as ants and birds, they help to reduce the population densities of insects significantly,” said Nyffeler. “Spiders thus make an essential contribution to maintaining the ecological balance of nature.”
In some parts of the world, spiders have a population density of 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.
It’s not the only recent spider discovery likely to give arachnophobes the creeps.
Earlier this month, Matthew Persons, an American biology professor, revealed that wolf spiders have threesomes to reduce the risk of being eaten after sex.