Inside the cave with the world’s biggest spider web

Inside the cave with the world’s biggest spider web

In a low, narrow passage where Albania meets Greece, researchers stepped into a limestone chamber carved by the Sarantaporos River and found a web the size of a small home. According to a report in the New York Times, the sheeted lattice covers roughly 1,140 square feet, shimmering when headlamps catch the silk. The cave is warm year-round and rich in hydrogen sulphide, an inhospitable mix for most animals but a protective moat for the life that adapts to it.

Two rivals share one web

Counting and sampling revealed a metropolis of roughly 111,000 spiders living under the same roof. Most belonged to the barn funnel weaver, Tegenaria domestica, with a large contingent of Prinerigone vagans, a smaller web-builder that the barn funnel weaver often preys upon outside. Underground, something changes. Scientists hypothesise that the perpetual darkness blunts visual cues that trigger aggression, allowing the two species to coexist and weave a patchwork of thousands of individual funnels into one sprawling structure.

Why the food supply matters

The cave teems with more than two million midges that drift into the silk and fuel the colony. With calories abundant, competition eases and predation pressure drops. The result is a dense settlement where spiders can repair and extend their funnels faster than gravity and moisture tear them down.

How the mega-web keeps standing

The web is not a single sheet spun at once. It is a living stack of layers. Old silk sags and sloughs off. New funnels bridge the gaps and bind to the ceiling and walls, creating a resilient sponge of fibres that flexes when touched and springs back. Researchers describe the texture as soft and buoyant, a property that helps dissipate the weight of moisture and the constant pelting of insects.

Genes hint at adaptation

Specimens from the cave show genetic differences from relatives outside, suggesting a population that is adapting to its sulphur-rich, lightless niche. Warmer temperatures, stable humidity and chemical exposure may be nudging physiology and behaviour in directions that favour cooperation and continuous web maintenance. The genetic signal does not prove a new species, but it strengthens the case that isolation and environment are reshaping familiar spiders into specialised cave dwellers.

Why scientists are cautious

The headline numbers are astonishing, and the methods are careful, but the team notes uncertainties. Measuring an object this irregular means some inactive or abandoned silk could have been included in area estimates. Population counts extrapolate from sampled zones to the whole lattice. Even so, independent arachnologists say the figures are plausible given the cave’s heat, gas chemistry and food supply.

The human effort behind the find

Reaching the site is not easy. The team waded through chest-high water, clipped to ropes, masks strapped on against the rotten-egg sting of hydrogen sulphide. They returned across seasons from 2023 to 2025, building a case strong enough for a peer-reviewed paper and a fresh line of inquiry: when resources are rich and senses are muted, how far can cooperation stretch among species that are usually enemies?