Putting this figure into context, spiders catch, kill and eat approximately the same amount as the weight of meat and fish eaten every year by the total human population on the planet. This is based on a study run by Dr Martin Nyffeler, who works at the University of Basel scientist. Dr. Nyffeler set out to test a hypothesis, first made in 1958 by William Bristowe in a book called The World of Spiders. This was that the weight of insects killed each year by the British spider population exceeded the combined weight of the British human population. This hypothesis had never been tested and, in setting out to test it, Dr. Nyffeler has done so accounting for the estimated global spider population.
To get to the position where a reliable estimate of the food eaten by the world’s spiders could be made has taken 40 years, Dr. Nyffeler has told BBC Sciece, stating the task involved “spending thousands of hours dealing with spider prey capture rates and prey selection – was needed to be able to write this paper on the global annual prey kill of the spiders.” Due to their secretive lifestyle—some species are for example nocturnal or hunt in litter and soil habitats—the predatory activities of the spiders has remained largely unnoticed and it has been a slow task to estimate the impact of spiders their on prey. To develop his research Dr. Nyffeler worked with Dr. Klaus Birkhofer of Lund University in Sweden.
Some of the most interesting facts from the research are:
The entire population of the world’s spiders weighs 25 million tonnes.
The world’s spiders hunt and eat between 400 million and 800 million metric tonnes of insect prey annually. This is based on fresh weight.
Forests and grasslands account for more than 95 percent of the annual prey kill of the global spider community.
Spiders provide food for other animals. There are 8,000-10,000 specialized insect species and up to 5,000 passerine birds which feed on spiders.
The new research has been published in the journal Science of Nature. The paper is titled “An estimated 400–800 million tons of prey are annually killed by the global spider community.”
