Fish-Eating Spiders Widespread Except in Antarctica

All spiders feed on a wide range of insects but scientists have found that spiders even prey on small fish.

In a new finding, Arachnologist Martin Nyffeler, of the University of Basel in Switzerland, and fish ecologist Brad Pusey, of the University of Western Australia discovered that spiders all over the world at times supplement their diet catching small fish that lurk near swamps, ponds and rivers.

The researchers documented numerous incidents of spiders preying on fish from almost all around the world. Based on the review, they found that spiders from as many as five families prey on small fish in the wild and three more families were seen eating fish in lab settings.

Referred to as the semi-aquatic spiders, these spiders dwell in shallow fresh water streams. Some of these have the ability to swim, dive and walk on the surface of the water and have strong neurotoxins and enzymes that help them kill and digest the fish bigger than them in size.  

"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", says Martin Nyffeler.

Fish-eating spiders were seen across all continents except Antarctica. Most of these semi-aquatic spiders were seen in North-America, mainly the wetlands of Florida and they were often seen preying on small freshwater fish such as the mosquito fish.

To catch the prey these spiders fix their hind legs to a stone or plant and rest their front legs on the water surface. They are always ready to attack their prey and on grabbing one they drag it to a dry place and then begin their feeding process that lasts for several hours.

The finding is documented in the journal PLOS One.