Largest multi-species spider web

The largest spider web on record collectively created by spiders from more than one species was discovered on the wall of a narrow low-ceilinged passage near the entrance of Sulfur Cave, situated on the Albania-Greece border, and formally documented on 17 October 2025 in the journal Subterranean Biology. Spanning an area of 106 m2 (1,141 sq ft), the colony that created it comprises an estimated 69,000 individuals belonging to the domestic house spider, aka barn funnel weaver (Tegenaria domestica) and more than 42,000 individuals belonging to the common sheet weaver (Prinerigone vagans). Existing in pitch darkness there, this enormous composite web consists of thousands of individual funnel-shaped webs linked together like a patchwork quilt.

In addition to its huge size, this composite web is particularly remarkable inasmuch as the two species that have combined forces to create it were not previously known to cohabit and cooperate in colonial web creation. This veritable spider megacity was first brought to scientific attention in 2022, when cavers with the Czech Speleological Society discovered it during an expedition in the Vromoner Canyon. A team of scientists then visited the cave in 2024, plucking specimens from the web for identification purposes.

The study published in Subterranean Biology was a collaboration between the Sapientia Hungarian University of Transylvania, Emil Racoviţă Institute of Speleology, “Grigore Antipa” National Museum of Natural History (all Romania), University of Tirana (Albania), University of Maastricht (Netherlands), Université libre de Bruxelles, Vrije Universiteit Brussel, Interuniversity Institute of Bioinformatics, Brussels Laboratory of the Universe (all Belgium), University of Göttingen (Germany), Mediterranean Natural History Museum (Italy) and California State University (USA), led by István Urák of the Sapientia Hungarian University of Transylvania.