The discovery of the world’s largest spider web; The city with 111 thousand spiders!

In the depths of a sulfur cave and in absolute darkness on the border between Greece and Albania, researchers have managed to discover an amazing phenomenon; A huge colony of over 111,000 spiders that seem to have built the world’s largest spider web. This discovery is of great scientific importance not only because of its huge dimensions, but also because it reveals an unprecedented social behavior in two common spider species.

This extraordinary colony is located in a completely dark area of ​​the cave. This giant web, which is actually a collection of thousands of separate funnel-shaped webs, covers an area equal to 106 square meters along the wall of a narrow passage. The results of this research were published on 25 Mehr 1404 (17 October 2025) in the journal Subterranean Biology.

Analysis of the samples showed that two species of spiders live in this colony. This discovery is unique in that these two species were not previously known for social life and cooperation on such a large scale. This is a unique case of two species coexisting in a cobweb structure with such a large population, says Istvan Orak, lead author of the study.

This spider colony is located in Sulfur Cave; A cave formed due to the presence of sulfuric acid resulting from the oxidation of hydrogen sulfide in underground water. In this environment, spiders feed on small, non-biting mosquitoes, which themselves feed on the white microbial layers (biofilm) of sulfur-oxidizing bacteria in the cave. This complex food chain has helped this huge population survive in total darkness.

Molecular data also show that cave spiders are genetically different from their non-cave relatives, indicating their adaptation to their dark and unique environment. According to Orak, some species show remarkable genetic flexibility that is usually revealed only under extreme and unusual conditions.