{"id":121039,"date":"2025-11-07T19:44:12","date_gmt":"2025-11-07T19:44:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/il\/121039\/"},"modified":"2025-11-07T19:44:12","modified_gmt":"2025-11-07T19:44:12","slug":"over-111000-spiders-of-two-different-species-coexist-in-pitch-black","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/il\/121039\/","title":{"rendered":"Over 111,000 Spiders of Two Different Species Coexist in Pitch Black"},"content":{"rendered":"

A remote cave system nestled along the border of Greece and Albania has revealed what may be the largest known spider colony on Earth\u2014and possibly the largest web ever documented. The discovery, made by a team of European biologists, challenges long-held assumptions about arachnid behavior and adaptation, particularly among species once thought to be strictly solitary.<\/p>\n

The cave, known as Sulfur Cave, houses a web complex sprawling over 100 square meters (approximately 1,076 square feet \u201c100 m\u00b2\u201d), constructed from thousands of interconnected funnel-shaped silken structures. What\u2019s more, the structure is cohabited by more than 110,000 spiders from two distinct species\u2014Tegenaria domestica and Prinerigone vagans\u2014living together in apparent harmony.<\/p>\n

\"\"The layout of Sulfur Cave. (Ur\u00e1k et al.,\u00a0Subterr. Biol., 2025)<\/p>\n

The finding, first reported in the peer-reviewed journal Subterranean Biology<\/a>, documents not only the size of the structure but also a previously unknown form of facultative colonialism in two species historically observed in isolation. The team\u2019s analysis suggests this behavior may have emerged in response to the cave\u2019s uniquely sulfur-rich, lightless environment.<\/p>\n

\u201cWe weren\u2019t just observing webs\u2014we were witnessing architecture on a different scale,\u201d said Istv\u00e1n Ur\u00e1k, lead author and biologist at Sapientia Hungarian University of Transylvania. \u201cThis isn\u2019t just a habitat. It\u2019s an ecosystem engineered by spiders.\u201d<\/p>\n

A Thriving Ecosystem Built on Sulfur, Not Sunlight<\/p>\n

Unlike most ecosystems on Earth, Sulfur Cave is sustained not by photosynthesis, but by chemoautotrophic bacteria that feed on hydrogen sulfide emitted from the cave\u2019s geothermal springs. These microbes form dense biofilms, which serve as the base of an entirely subterranean food web.<\/p>\n

The researchers conducted stable isotope analyses (\u03b4\u00b9\u00b3C and \u03b4\u00b9\u2075N) to trace this food chain. Results confirmed that the spiders are primarily feeding on a native midge species (Tanytarsus albisutus), which in turn feeds on the microbial mats coating the cave walls. The entire ecosystem\u2014from microbes to midges to spiders\u2014functions independently of the sun.<\/p>\n

\"APart of the giant colonial web in Sulfur Cave. (Ur\u00e1k et al.,\u00a0Subterr. Biol., 2025)<\/p>\n

\u201cThis is a classic chemoautotrophic system, akin to what we see in deep-sea vents,\u201d said Serban Sarbu, a subterranean biologist and co-author of the study. \u201cBut what\u2019s remarkable here is how surface-dwelling species have colonized and adapted to such a radically different biochemical environment.\u201d<\/p>\n

Both spider species typically inhabit human dwellings or forested areas, making their presence in Sulfur Cave\u2014and their peaceful coexistence\u2014all the more unexpected. DNA sequencing revealed these cave-dwelling populations are genetically distinct from their surface counterparts, showing no evidence of recent migration or interbreeding.<\/p>\n

Colonial Behavior Defies Evolutionary Expectations<\/p>\n

One of the most striking findings was the emergence of social web-building behavior in species long considered solitary. The funnel weaver T. domestica appears to be the primary architect of the web complex, while P. vagans occupies existing sections without contributing to construction.<\/p>\n

Researchers expected interspecies predation, given that T. domestica is significantly larger than P. vagans. But field observations and spatial distribution <\/a>analyses suggest the two species rarely interfere with one another. One hypothesis is that the perpetual darkness of the cave may suppress aggressive behaviors by limiting visual cues.<\/p>\n

\u201cThere\u2019s almost no precedence for this kind of cohabitation among spiders,\u201d Ur\u00e1k noted. \u201cIt\u2019s an extreme example of environmental pressure rewriting behavioral rules.\u201d<\/p>\n

\"\"A female of the species\u00a0Tegenaria domestica\u00a0in one of the web\u2019s funnels. (Ur\u00e1k et al.,\u00a0Subterr. Biol., 2025)<\/p>\n

The researchers also documented seasonal shifts in egg sac size among T. domestica, with larger clutches recorded during early summer. Gut microbiome analysis further showed that cave-dwelling spiders had significantly lower microbial diversity compared to individuals of the same species found near the cave entrance, a likely consequence of a more limited and homogeneous diet.<\/p>\n

The Cave\u2019s Complex Subterranean Network<\/p>\n

Sulfur Cave is part of a larger limestone system that includes Atmos Cave and Turtle Cave. The network extends across national borders, with the entrance located in Greece and deeper corridors reaching into Albania. Water from sulfur-rich springs flows through the caves, eventually joining the Sarandaporo River.<\/p>\n

\"\"The web and a swarm of midges. (Ur\u00e1k et al.,\u00a0Subterr. Biol., 2025)<\/p>\n

The cave\u2019s inner walls are covered in slimy microbial films, forming a continuous substrate that supports a wide array of invertebrates including centipedes, pseudoscorpions, mites, and beetles. Notably, many of these species also appear to be genetically unique, suggesting a high degree of endemism driven by chemical isolation and evolutionary pressure.<\/p>\n

What began as a casual discovery by recreational cavers in 2022 has quickly evolved into a significant biological investigation. The full scope of the ecosystem\u2014both in terms of biodiversity and evolutionary adaptation\u2014remains under study.<\/p>\n","protected":false},"excerpt":{"rendered":"A remote cave system nestled along the border of Greece and Albania has revealed what may be the…\n","protected":false},"author":2,"featured_media":121040,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[85,46,141,386],"class_list":{"0":"post-121039","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-il","9":"tag-israel","10":"tag-science","11":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/121039","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=121039"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/121039\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/121040"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=121039"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=121039"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=121039"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}