Spiders don't just eat insects, but also several types of small fish, a new study shows.  

These arachnids are usually considered insectivores. However, zoologists have found fish-eating spiders from all parts of the world except Antarctica.

For the present study - Martin Nyffeler from the University of Basel, Switzerland, and Bradley Pusey from the University of Western Australia, gathered and documented information about spiders that eat fish. They found 89 such instances of spiders preying on fish.

Researchers say that they have found 18 different spider species that catch fish in the wild and another six species that ate fish in laboratory settings, Livescience reported.

These semi-aquatic spiders live near shallow streams or ponds. Some of these spiders can swim, dive or even walk on water. They carry neurotoxins that help them kill and eat the fish, according to a news release.

"Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders' body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance," the authors wrote in the study.

Previously, Nyffeler has published reports of spiders that hunt earthworms and even bats. These studies show that spiders have varied diets. "Rarely, this scattered information is processed and synthesized," Nyffeler said, according to Livescience. "Very few scientists look at things from a global perspective."

So, how do these eight-legged creatures fish? Researchers said that spiders adopt the wait-and-watch strategy while fishing.

"The spider typically assumes a position near the water's edge, with the rear pair of legs anchored to some vegetation or wood or rock, and their three front pairs of legs out of the water's surface," Pusey told Live Science.

Once a fish swims too close to the surface, the spider attacks it and injects a dose of neurotoxin. The spider then drags the fish out of the water.

The study is published in the journal PLOS One.