Spiders beat humans, whales by consuming upto 800 million tones of prey each year

New Delhi: They may be small in size, but turns out spiders really are mighty as they consume an astonishing amount of prey each year, making them one of the most prolific predators on the planet.

Researchers have revealed that spiders wipe out an estimated 400-800 million tonnes of prey every year, compared to an estimated 280-500 million tonnes of prey that the world's whales eat.

And more than 90 per cent of spider prey is insects and springtails (Collembola).

 

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.

"Our calculations let us quantify for the first time on a global scale that spiders are major natural enemies of insects," said lead author of the study Martin Nyffeler from the University of Basel in Switzerland.

"In concert with other insectivorous animals such as ants and birds, they help to reduce the population densities of insects significantly," he added.

The research also showed that spiders kill many times more insects in forests and grasslands than in other habitats.

Due to their secretive lifestyle - many spiders are nocturnal or live well camouflaged in vegetation - it was previously difficult to demonstrate their ecological role, but the zoologists at the University of Basel and Lund University in Sweden used calculations to conclude that spiders indeed have an enormous ecological impact as natural enemies of insects.

The researchers used two calculation methods based on different models, which consistently showed that the global spider population (with a weight of around 25 million tons) wipes out an estimated 400-800 million tons of prey every year.

According to the Food and Agriculture Organisation of the United Nations, worldwide human population consumes around 400 million tonnes of meat and fish every year.

Whales in the world's oceans eat an estimated 280-500 million tonnes of prey a year.

The new findings have been published in the journal The Science of Nature.

(With IANS inputs)