Researchers Explain Unique Behavior of a Spider Species

Spiders are loners, hunting and living on their own. However there is one species of spider that lives in a colony-like arrangement with other spiders of its kind. A team of researchers has now found how this spider species- Parawixia bistriata- lives in a colony.

The spiders of this species stay together in a bivouac, which is a soccer-like arrangement made of hundreds of spiders. The bivouac exists at the center of a tree with strong spider web-lines radiating outside. These lines connect nearby tree branches with the bivouac. Spiders usually spend the daytime in these bivouacs.

At night, all the spiders begin to drift away from the bivouac along these web lines and build individual webs, each of which is linked with thousands of other webs. By daybreak spiders consume their prey along with their webs and return back to the bivouac.

These spiders pick a spot to build their nest by fending off any intruders during early evening. They usually do this by bouncing up and down the web-lines.

Now, there is only a limited amount of space available for spiders and often they dont get a place to build their webs along the web lines. When this happens, the "webless spiders" just hang around the already-built nest and freeload on prey caught by the resident spider.

"Charles Darwin almost certainly observed this species while travelling overland in Argentina in October 1832, describing them in his Voyage of the Beagle as 'many large black spiders, with ruby-coloured marks on their backs, having gregarious habits'.... 'this gregarious habit, in so typical a genus as Epeira, among insects, which are so bloodthirsty and solitary that even the two sexes attack each other, is a very singular fact," Professor Jonathan Bacon, one of the study authors from the University of Sussex.

Interestingly, the resident spiders don't fight over food with the freeloader spiders. Living in a colony helps these spiders avoid being eaten by predators, researchers added.

The study is published in the journal The American Naturalist.