World's biggest spider web spans two countries and houses more than 100k creepy crawlies

Scientists have discovered a colossal spider web thought to be the largest in the world that plays host to more than 100,000 creepy crawlies. In startling images that are sure to strike fear into any arachnophobe, a vast communal web can be seen covering a cave wall, dubbed Sulfur Cave, on the border between Albania and Greece. 

Found in 2022 by cavers from the Czech Speleological Society and later analysed by scientists, the web spans an impressive 106 square metres and features two distinct species, 69,000 domestic house spiders (barn funnel weaver) and 42,000 Prinerigone vagans (a type of sheet weaver spider), reports Discover Wildlife. Situated in sulphur caves formed by sulphuric acid as part of a process that involves hydrogen sulphide reacting with oxygen, the web's location is within a cave system that has an entrance in Greece but crosses into Albania.

Its enormous size isn't the only notable aspect of this discovery, however; it also marks the first time that a web created by multiple species has been recorded.

The barn funnel weaver is a predatory species and will normally feed on smaller spiders, such as the aforementioned sheet weaver, making the find particularly unusual.

Speaking to As It Happens' Nil Köksal, and reported by CBC, scientist Serban Sarbu said: “To find so many spiders in one spot in a cave, that was the first surprise. So [then], you ask yourself the question, ‘Why are they there? What’s, in fact, keeping them alive?’”

It’s believed that the absence of light and access to midges or flies as a source of food for both species meant that the spiders didn’t need to leave the cave, according to the BBC.

The scientists, writing in the journal Subterranean Biology, said: “The colonisation of Sulfur Cave by T. domestica was most likely driven by abundant food resources represented by the dense swarm of chironomids [midges] thriving in the cave.”

The cave is home to other animal species, too, including scorpions, centipedes, bats, beetles and chironomid fly larvae, which become trapped in the web when they mature.

Sarbu said: “They become trapped there and then the spiders get out of their little funnel holes and catch the flies and eat them.”

In related news from October, the BBC reported that an endangered species of spider, known as Aulonia albimana (a type of wolf spider), was rediscovered on the Isle of Wight, marking 40 years since it was last documented.

It was found at the National Trust’s Newtown nature reserve. Mark Telfer, who formed part of the search, described it as an “unforgettable” discovery.

He said: “To find a species thought lost for 40 years is thrilling – and testament to how the right habitat management, combined with curiosity and collaboration, can deliver remarkable results.”