Pescatarian spiders munch on fish all over the world

Written by: Lisa Stelzner

Primary Source: Daily Dose of Science Blog

Although scientists have known there were a few types of fish-eating spiders out there, we recently just discovered there are many more than we once thought. There are 26 known spider species that eat fish from eight families, and some have been observed doing this behavior in the wild.  The spiders do this by dangling their front legs in water while they sit on a leaf at the surface, paralyzing a fish that comes by with neurotoxins, and dragging the fish away onto land to consume it.  Surprisingly (at least to me), half of the wild observations were in the U.S. and not in the tropics!  There are a ton of spiders of the Dolomedes genus in Florida, where they feast on mosquitofish. They are also found in the U.K., Australia, and South America – in fact, on every continent except Antarctica.These fish-eating spiders are only able to eat small fish – the largest fish one was spotted eating was 9 inches long (still huge for a spider).  They probably still get most of their food from insects, but fish are a nice, big, protein-rich meal that they can enjoy

You crazy, fish-eating spider.  Photo credit:  Patrick Randall.

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Lisa Stelzner
I'm a plant biology PhD student studying monarch butterflies in Michigan, but I'm interested in lots of other types of science, too. I am interested in how breeding monarch butterflies choose their habitat based on floral species richness and abundance. Few studies have been conducted on optimal foraging theory when it involves an organism searching for two different kinds of resources, and butterflies are an ideal study system to investigate this, since many species are ovipositing specialists and only lay eggs on one species of hostplant, but are feeding generalists and nectar from a broad variety of flowering forbs.