Spiders eat more insects than humans eat meat
The present study was conducted by biologist Klaus Birkhofer at the Faculty of Science at Lund University in Sweden. Together with a researcher in Switzerland he has analysed how much these eight-legged carnivores consume in a year.
“Many people are afraid of spiders and find them unpleasant. I hope that this study will help people better understand the good things that spiders do”, says Klaus Birkhofer.
Spiders keep pest insects in check. The enormous amount of insects that spiders eat would otherwise cause major damage to agricultural crops and forests. But that’s not all.
“For example, in areas with malaria the spiders help by catching mosquitoes that can infect humans”, says Klaus Birkhofer.
To estimate how many spiders there are in the world, the researchers based their calculations on data from 65 previous studies. They then figured out the amount of prey that spiders kill every year in order to survive. The answer is between 400 and 800 million tons. By comparison, the world’s whales consume between 280 and 500 million tons per year.
More than 90 per cent of the spiders’ prey are insects and springtails. Large spiders in the tropics can also catch and eat other animals such as frogs, lizards, birds and bats.
The results from the study are published in The Science of Nature.
Text: Jan Olsson