Ray-spider
Guides
Theridiosoma
ray spiders
Theridiosoma is a genus of ray spiders (family Theridiosomatidae) first described by Octavius Pickard-Cambridge in 1879. These small spiders, measuring 0.5–2.5 mm in body length, are renowned for their unique hunting behavior: they construct specialized webs that function as high-speed slingshots to actively capture prey. The genus contains approximately 33 species distributed globally, with records from North America, Europe, Asia, Central and South America, Africa, Oceania, and the Caribbean.
Theridiosoma gemmosum
Common Eastern Ray Spider, Ray Spider
A small Holarctic ray spider distinguished by its unique conical orb web. Females measure 2–3 mm, males 1.5–2 mm. The species constructs a specialized web held under tension by the spider, which is released to snap forward and capture flying prey. Mating involves successive copulations with males providing silk draglines that females ingest as nuptial gifts between copulations.
Theridiosomatidae
ray orbweavers, ray spiders, slingshot spiders
Theridiosomatidae is a small family of orb-weaving spiders known for constructing distinctive cone-shaped or slingshot webs. The family comprises approximately 137 extant species in 20 genera, distributed primarily in tropical and subtropical regions worldwide. Members are commonly called "ray spiders" or "slingshot spiders" due to their unique web architecture where the web center is pulled back and anchored, then released to propel the spider toward prey. Most species are small, typically under 1 cm in body length. The family exhibits remarkable behavioral diversity in web construction, with some genera showing specialized adaptations including cave-dwelling and high-elevation habitat preferences.