| Sulfur Cave | |
|---|---|
 The world's largest spiderweb in the Sulfur Cave, illuminated by lights. | |
 Interactive map of Sulfur Cave | |
| Location | Konitsa, Greece Kolonjë, Albania |
| Coordinates | 40°05′46″N20°40′44″E / 40.0961°N 20.6789°E [1] |
| Length | 1,710 feet (520 m) [1] |
| Discovery | 2022 |
| Geology | Sulfuric acid |
| Entrances | 1 [1] |
The Sulfur Cave is a cave of the same name on the Greco-Albanian border, and an example of the broader phenomenon of Sulfuric acid caves [2] , and is known for containing the first reported super-colony of spiders, which are usually a solitary species. The cave was discovered in 2022 by cavers who then reported their discovery to scientists. The cave itself is over 97 square metres (1,040 sq ft) in size and contains over 111,000 spiders of the species Tegenaria domestica and Prinerigone vagans . [3] This is the first documented example of these 2 species of spider constructing webs together.
Sulfur acid caves are an extreme environment, being completely dark and filled with hydrogen sulfide gas, a gas which is toxic to most life-forms. Researchers were able to determine that the spiders in the cave feed on sulfur-oxidising microbes as their main food source. Additional genetic analysis also showed that the species inhabiting the cave are becoming distinct from their counterparts outside of the cave. They hypothesise that genetic isolation and an abundant food supply led them to develop colonial behaviour, which is unheard of in spiders.
One of the species in the cave, colloquially known as the funnel weaver spider is known to be predatory, and would normally eat the other species of spider in the cave with it, the sheet weaver spider. However, a lack of light and the amount of food available in the cave were judged to be the two main reasons why this didn't happen. The ecosystem is fuelled by microbes which feed on the toxic gas in the cave. These are then eaten by crustaceans, which are then eaten by midges and flies the spiders use as a food source.