Spiders found on almost every continent in the world feast on fish by hunting them then dragging them to dry land, where they devour the creature over several hours, scientists have discovered.

Zoologists from Australia and Switzerland found that spiders from at least five different families eat fish far bigger than themselves.

While traditionally viewed as insectivorous – or a predator of insects – experts are becoming increasingly aware that spiders will eat other forms of meat to survive.

Published in PLOS ONE, the study showed spiders both in the wild and laboratory conditions hunting, killing and eating fish.

"These so called semi-aquatic spiders typically dwell at the fringes of shallow freshwater streams, ponds or swamps," a statement from the University of Basel said. "These spiders, some of which are capable of swimming, diving and walking on the water surface, have powerful neurotoxins and enzymes that enable them to kill and digest fish that often exceed them in size and weight."

spider eating fish
Fishing spider Dolomedes facetus captured fish in garden pond near Brisbane, Australia. Peter Liley, Moffat Beach, Queensland

The only place spiders have not been observed eating fish is Antarctica. They were most commonly found in parts of North America, especially the wetlands in Florida, where mosquitofish is a regular on the spider menu.

Spider expert Martin Nyffeler said: "The finding of such a large diversity of spiders engaging in fish predation is novel. Our evidence suggests that fish might be an occasional prey item of substantial nutritional importance."

Explaining the killing process, the study's authors said: "In order to catch its prey, the spider will typically anchor its hind legs to a stone or a plant, with its front legs resting on the surface of the water, ready to ambush. The fish will then be dragged to a dry place before the feeding process can begin which usually lasts several hours."