Arachnophobes best look away now, because a group of scientists have found what could be the biggest spider colony in the world.
The web is 106 square metres (1,140 square feet) in size and is thought to be home to up to 111,000 spiders. That’s roughly half the size of a tennis court.
The researchers, who recently published their findings in Subterranean Biology, found the colossal colony was crafted by two different species of spider.
The spider colony is located on the border of Greece and Albania in the Vromoner Canyon, in a section called the Sulfur Cave.
The web stretches along a narrow, low-ceilinged passage 50m (164ft) from the entrance, in a permanently dark part of the cave. It is made from a multi-layered patchwork of individual funnels, which combine to form a spongy mass.
According to the researchers’ estimates, the colony is home to around 69,000 Tegenaria domestica (also known as barn funnel weavers or common house spiders) and 42,000 Prinerigone vagans spiders.
While these two species are often found close to each other, they don’t normally coexist so closely.
In fact, the barn funnel weavers usually prey upon the smaller Prinerigone vagans. The researchers suspect that the poor light in the cave is impairing the spider’s vision, leading to the unlikely truce.
Instead, the spiders eat non-biting midges, which have an unusually dense swarm near the colony. These in turn feed on bacteria that are sustained by a sulphur-rich stream, which is fed by a natural spring and runs through the cave.
DNA analysis of the spiders revealed that they are genetically distinct from their outside relatives, suggesting they have adapted to their environment.
Meanwhile, their sulphur-rich diet has resulted in their gut microbiomes becoming a lot less diverse.
Both of these suggest the spiders do not mix with their cousins on the surface.
The colony was first discovered in 2022 by a group of cavers from the Czech Speleological Society, who were exploring the region.
The team of researchers then ventured into the cave in 2024. They estimated the number of spiders in the colony by counting the number of web funnels, before taking several specimens for more in-depth study.
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