What is thought to be the world\u2019s largest-known spider\u2019s web, housing tens of thousands of\u00a0arachnids, has been discovered in a cave on the Albanian-Greek border.<\/p>\n
After researchers published their findings of two different spider species peacefully cohabiting in a giant colony nestled in a pitch-black, sulfur-rich cave, evolutionary biologist Lena Grinsted likened the \u201cextremely rare\u201d occurrence to humans living in an apartment block.<\/p>\n
\u201cWhen I saw this study, I was very excited because \u2026 group living is really rare in spiders,\u201d Dr. Grinsted, a senior lecturer at the U.K.\u2019s University of Portsmouth, told The Associated Press. \u201cThe fact that there was this massive colony of spiders living in a place that nobody had really noticed before \u2014 I find extremely exciting.\u201d<\/p>\n
READ MORE: How the itsy bitsy spider evolved from a giant prehistoric sea creature<\/a><\/p>\n The results of the study, published last month in the journal Subterranean Biology, spread rapidly online due to the striking images of the giant 1,140-square-foot spider\u2019s web, a carpet-thick sprawl stretching along a narrow passage wall inside Sulfur Cave, which extends into Albania from its entrance in Greece.<\/p>\n This arachnophobe\u2019s worst nightmare was quickly labelled the \u201cworld\u2019s largest spider web.\u201d<\/p>\n But the most surprising thing about the spider colony \u2014 which boasts an estimated 110,000 spiders \u2014 had less to do with its size and more to do with what scientists found inside the huge mass of funnel-shaped webs.<\/p>\n Two different spider species \u2014 about 69,000 Tegenaria domestica, or common house spider, and 42,000 Prinerigone vagans \u2014 were living side by side and thriving. The behavior, which had never been observed before, stunned scientists as, typically, the larger house spider would prey on its smaller neighbor.<\/p>\n \u201cSo often if you have spiders in close vicinity, they will fight and end up eating each other,\u201d said Dr. Grinsted, who was not part of the cave study but has extensively researched spiders. \u201cWe can sometimes see that if there\u2019s an abundance of food that they sort of become a bit less aggressive.\u201d<\/p>\n Abundant food source<\/p>\n Scientists are keen to understand how and why the two species came to coexist peacefully in a \u201cpermanently dark zone\u201d about 50 meters (164 feet) from the entrance of the cave, carved out by the waters of the Sarandaporo River to form the Vromoner Canyon.<\/p>\n Part of the answer, the research suggests, may lie in the combination of the estimated 2.4 million midge flies that buzz around the spider colony \u2014 an \u201cunusually dense swarm\u201d that provides a constant food source in an otherwise predator-scarce environment. The scientists also speculate that the friendly living arrangement could be a result of darkness impairing the spiders\u2019 vision.<\/p>\n However, Dr. Grinsted says it is more likely that the larger spiders evolved or simply grew accustomed to responding to vibratory cues when the small flies land on their silken web \u2014 and maybe don\u2019t attack otherwise.<\/p>\n \u201cSpiders, in general, are not particularly good at seeing stuff \u2026 and that includes these two species,\u201d she said. She added that the two species might cooperate \u201cto some extent in building the web \u2026 but I think it\u2019s highly unlikely that they cooperate in anything else like prey capture, in brood care, or looking after each other\u2019s babies.\u201d<\/p>\n Dr. Grinsted draws parallels between the cohabiting spiders and how humans tend to coexist in apartment blocks.<\/p>\n \u201cYou\u2019re very happy to share the stairs, the lift,\u201d she said. \u201cBut if anybody comes into your living room and you haven\u2019t invited them, you\u2019ll be aggressive towards them.\u201d<\/p>\n She added that while many spiders are \u201ctypically solitary, very aggressive\u201d toward other critters, the cohabitation of two species is \u201crelatively common\u201d once spiders have evolved the ability to live in groups.<\/p>\n \u201cBut again, because these two species have never been found to live together and never been found to live in groups, it makes it particularly exciting,\u201d she said.<\/p>\n \u2018The web is dense \u2014 like a blanket\u2019<\/p>\n Dr. Blerina Vrenozi, a biologist and zoologist at the University of Tirana, in Albania, who co-authored the research paper, told the AP that the expeditions this year helped understand \u201chow this mystery existed in there.\u201d<\/p>\n \u201cThe DNA is interesting because they revealed that the species which live inside the cave is different from the one which lives outside the cave,\u201d she said. \u201cSo it\u2019s the same species, but different DNA.\u201d<\/p>\n