![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2025\/11\/spider-web-642x361.jpg\")
Part of the giant colonial web in Sulfur Cave. (Ur\u00e1k et al., Subterr. Biol., 2025)<\/p>\n
It’s the first documented case of true colonial<\/a> web formation in both of these species, says a team led by arachnologist Istv\u00e1n Ur\u00e1k of Sapientia Hungarian University of Transylvania.<\/p>\n Not only do they have unique behaviors, the cave-dwelling spiders have genetic differences from their surface-dwelling kin, suggesting they are adapting to their isolated habitat.<\/p>\n Related: Scientists Translated a Spiderweb Into Music, And It’s Eerily Captivating<\/a><\/p>\n “Our findings,” the researchers write<\/a>, “unveil a unique case of facultative coloniality in this cosmopolitan spider, likely driven by resource abundance in a chemoautotrophic cave, and provide new insights into the adaptation and trophic integration of surface species in sulfidic subterranean habitats.”<\/p>\n Sulfur Cave is a subterranean network of interconnected limestone<\/a> chambers, with the entrance in Greece, and the body of the cave crossing the border into Albania. The spider megacity was first spotted in 2022 by recreational cavers, who alerted scientists after stumbling across the strange silken expanse.<\/p>\n Subsequently, scientists made several visits<\/a> to the cave to understand its highly unusual habitat. It’s not just the size \u2013 massive cave walls coated with webs \u2013 but the cohabitation: Although both spiders are quite common, neither had ever been seen living colonially, let alone peacefully alongside each other.<\/p>\n Tests of the web show that the barn funnel weavers handled the construction of the web, and the sheetweb spiders simply moved their arachnid butts in and took up residence, cheek-by-pedipalp.<\/p>\n The vast sheet, the researchers ascertained, consists of thousands of individual funnel-shaped webs, overlapping and interconnected<\/a>.<\/p>\n Genetic, microbiome, and isotope analyses revealed distinct cave-dwelling lineages isolated from their surface relatives and showing no signs of population exchange. Generations of isolation have reshaped both their genes and gut microbes. The colony appears to be completely cut off from the surface world.<\/p>\n Then the isotope analysis got to the meat of the matter \u2013 quite literally. The spiders were not eating insects that had somehow blundered into the cave, but insects that had been born there.<\/p>\n As the name suggests, Sulfur Cave is rich in sulfur, an element that supports an ecosystem based on sulfur-metabolizing microbes, out of reach<\/a> of the life-giving light of the Sun that supports food webs based on photosynthesis<\/a>.<\/p>\n In the cave, chemoautotrophic<\/a> microbes congregate to feast upon the available chemicals, forming microbial mats. These microbial mats then attract predators such as centipedes, midges, isopods, beetles, springtails, and various arachnids.<\/p>\n The isopods and springtails eat the microbes; midges and spiders eat the isopods and springtails; and the spiders also feast, mightily, upon the abundant midge population. The most densely webbed sections of cave wall were those where midges were most numerous.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2025\/11\/cave-map.jpg\")
The layout of Sulfur Cave. (Ur\u00e1k et al., Subterr. Biol., 2025)<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2025\/11\/spider-cave.jpg\")
A female of the species Tegenaria domestica in one of the web’s funnels. (Ur\u00e1k et al., Subterr. Biol., 2025)<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2025\/11\/web-swarm.jpg\")
The web and a swarm of midges. (Ur\u00e1k et al., Subterr. Biol., 2025)<\/p>\n
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