Cobweb Spiders, Theridiidae
Theridiidae is a family that contains over 2,200 species of cobweb spiders, also known as tangle-web spiders or comb-footed spiders, which can be found throughout the world. This species received its common names from its tendency to build three dimensional, sticky webs and from the comb of serrated bristles on the fourth leg. It is thought that this family is the only to hold a high diversity of web types, including gumfooted webs, which are highly similar to those produced by spiders in the Nesticidae family. Some of the largest genera in the family include Theridion, which holds over six hundred species, and Parasteatoda, which holds the common house spider of North America.
The physical appearance of species within the Theridiidae family varies greatly, with some spiders like those in the Argyrodes genus holding triangular shapes. These spiders are kleptoparasitic in nature, inhabiting the webs of other spiders and eating their prey. Some species, like the happyface spider from Hawaii, are used for studies pertaining to color genetics, while others, including those in the Anelosimus genus, are used to study social structures and reproduction habits of spiders. The black widow spider, among other widows, is a member of this family and is often the subject of medical studies.
Image Caption: Female comb-footed spider (family Theridiidae), Enoplognatha ovata. Photographed in the wild at DuPage County, Illinois, USA. Size = 15mm. Credit: Bruce Marlin/Wikpedia (CC BY 3.0)