Fish-eating spiders conquer every continent

Spiders capable of catching and eating fish have been found on every continent except Antarctica.

In news that will disturb the sleep of arachnophobes around the world, researchers have found three families of large, semi-aquatic spider that prey on fish significantly bigger than themselves.

According to evidence gathered by Martin Nyffeler from the University of Basel in Switzerland and Bradley Pusey from the University of Western Australia, fish may in fact be a significant part of some spiders' diets.

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"Our evidence suggests that fish might be an occasional prey item of substantial nutritional importance," said Dr Nyffeler.

The scientists' research showed that three families spider capable of swimming, diving and walking on water, can also catch fish under laboratory conditions.

According to the report, these semi-aquatic species catch fish that are, on average, more than twice as long as they are.

The most common hunting technique is for the spider to anchor its hind legs on a stone or plant and rest its front legs on the surface of the water. When a fish strays too close, the spider will pounce and drag the fish to dry land to be eaten. The spiders then pump digestive enzymes into their prey before sucking out the dissolved tissue in a process known as "extra-intestinal digestion". The whole procedure tends to take several hours.

Most of the arachnids that have been observed catching fish in the wild are found in North America, particularly in the wetlands of Florida. But the new research shows that the practice is significantly more widespread than previously thought. Scientists were also surprised by the size disparity between the spiders and their prey.