Scientists have identified what appears to be the world’s largest contiguous spider web in Sulfur Cave on the Greece–Albania border. The web spans 1,076.4 square feet and shelters about 110,000 spiders, primarily 69,000 Tegenaria domestica and 42,000 Prinerigone vagans. Genetic tests show the cave populations are distinct, and T. domestica displays larger egg clutches in early summer. The cave also hosts 512 other species from 20 families, and the web — first noted in 2022 — was recently analyzed in detail.
World’s Largest Known Spider Web Found in Sulfur Cave — 110,000 Spiders Share 1,076.4 sq ft
Scientists have identified what appears to be the world’s largest contiguous spider web in Sulfur Cave on the Greece–Albania border. The web spans 1,076.4 square feet and shelters about 110,000 spiders, primarily 69,000 Tegenaria domestica and 42,000 Prinerigone vagans. Genetic tests show the cave populations are distinct, and T. domestica displays larger egg clutches in early summer. The cave also hosts 512 other species from 20 families, and the web — first noted in 2022 — was recently analyzed in detail.
05:32 AM, 11/12/2025Science
World’s Largest Known Spider Web Discovered in Sulfur Cave
Researchers exploring an underground cavern along the Greece–Albania border have documented what appears to be the world’s largest contiguous spider web, according to a study published in Subterranean Biology. The silk structure runs 1,076.4 square feet along a cave wall in Sulfur Cave and is currently inhabited by an estimated 110,000 individual spiders.
Two species, one giant web
Careful field counts and genetic analyses show the web supports roughly 69,000 individuals of Tegenaria domestica alongside about 42,000 of Prinerigone vagans. The researchers describe this as the first documented case of colonial web formation for these two species living together in a single, continuous silk structure.
“Molecular data confirmed the identity of the two spider species and revealed that their populations in Sulfur Cave are genetically distinct from other populations,”
The study also reports a seasonal pattern in reproduction for T. domestica, with significantly larger egg clutches observed in early summer.
A rich subterranean ecosystem
Sulfur Cave supports a remarkably diverse community: investigators recorded 512 additional species representing 20 families, all sustained by nutrients available within the cave ecosystem. The large web was first noted by the Czech Speleological Society in 2022 and has only recently been thoroughly examined and analyzed by the research team.
“It is a unique case of two species cohabiting within the same web structure in this huge number,”
István Urák of Sapientia Hungarian University of Transylvania, who analyzed samples from the site, described the finding as a striking example of nature’s ingenuity and the unexpected complexity possible in subterranean ecosystems.
Why it matters
The discovery is notable for several reasons: the exceptional size and density of the web, the cooperative (or at least cohabitative) behavior of species not typically viewed as social, and the genetic distinctiveness of the cave populations — all of which raise new questions about adaptation, reproduction, and community dynamics in isolated subterranean habitats.
Sources: Study in Subterranean Biology; initial reporting by the Czech Speleological Society (2022) and subsequent media coverage.