Video: Scientists Discover World's Largest Spiderweb Housing Over 110,000 Creatures

In what can only be described as an arachnophobe's worst nightmare, scientists have discovered the world's biggest spiderweb inside a deep, dark cave on the Albanian-Greek border. The colony, comprising 69,000 domestic house spiders and more than 42,000 dwarf weaver spiders, spans a total area of 1,140 square feet.

The researchers have been perplexed as to how the colony managed to sustain itself in a sulfur cave where there is a noticeable absence of sunlight and high levels of toxic hydrogen-sulfur gas.

"The large spider colony in Sulfur Cave was mainly observed on the left bank of the sulfidic stream of Sulfur Cave, in a permanently dark zone, starting at approximately 50 m from the cave entrance," the study published in the journal Subterranean Biology highlighted.

Sulfur Cave's spider colony is one of the largest ever documented, and the species involved weren't previously known to assemble and cooperate in this way.

"The colony covers a surface area of over 100 square meters and represents the first documented case of colonial web formation in these species," the study stated.

Lead author Istvan Urak, an associate professor of biology at Sapientia Hungarian University of Transylvania in Romania, said the two dominant spider species cohabiting together was a unique case.

"You have to experience it to truly know what it feels like. If I were to attempt to put into words all the emotions that surged through me [when I saw the web], I would highlight admiration, respect and gratitude," said Urak.

Scientists discovered the world's largest spiderweb, covering 106 m² in a sulfur cave on the Albania-Greece border.

Over 111,000 spiders from two normally rival species live together in a unique, self-sustaining ecosystem—a first of its kind.pic.twitter.com/LPLKVElSNv

— Massimo (@Rainmaker1973) November 6, 2025

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Food Habits

The researchers also discovered that the underground spiders consumed tiny midges that feed on sulfur-eating microbes that thrive in the cave environment. The sulfur-rich diet influenced the microbiomes of the spiders, causing them to be significantly less diverse than the microbiomes of spiders from the same two species outside the cave.

Molecular data also showed that the spiders inside the cave were genetically different from their relatives living outside, suggesting the cave-dwellers have adapted to their dingy surroundings.

Notably, cavers with the Czech Speleological Society first discovered the massive spiderweb in 2022. In 2024, a team of scientists visited the cave, collecting specimens that Urak and his team analysed before embarking on their own expedition.