Right now, as you read this, more than 110,000 arachnids are crawling around the world’s largest spiderweb.
The ‘extraordinary’ but skin-crawling discovery was made inside a pitch-black cave on the Albanian–Greek border.
The web stretches 1,140 square feet – about the size of a semi-detached house in the UK – and is home to two species of spider.
One is the Tegenaria domestica, otherwise called domestic house spiders, while the other is the far smaller sheet weaver, Prinerigone vagans.
Both live together within a patchwork of webs spread along the wall of a low-ceilinged passage, according to a study published in the journal Subterranean Biology.
The spider lair was discovered in the Sulfur Cave, a chamber hollowed out by sulphuric acid formed when hydrogen sulphide – an egg-smelling gas – from groundwater reacted with oxygen.
Spiders aren’t exactly known to be social creatures, so this might be the first example of two arachnids creating a colony, said study lead author István Urák.
‘The natural world still holds countless surprises for us,’ Urák told Live Science.
‘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.
‘You have to experience it to truly know what it feels like.’
The sprawling web was first spotted by cavers from the Czech Speleological Society in 2022.
Urák and his team visited the cave two years later to analyse the some69,000 T. domestica and 42,000 P. vagans lurking inside.
What took scientists off guard was that P. vagans are usually on the menu for the larger domestic house spiders.
They instead found the T. domestica nibbled on tiny, non-biting midges – though, they suggested this is because the lack of sunlight means the larger spiders simply can’t see their smaller housemates.
By peaking inside the stomachs of both spiders, the researchers found that they are one part of a complex ecosystem.
The midges feasted on by domestic house spiders eat white microbial biofilms, the slimy cling film that sulphur-oxidising bacteria exert.
By indirectly eating these bacteria, the spiders were enjoying a sulphur-rich diet that made them less diverse over time.
Rather, these creepy-crawlies had adapted to life in darkness and rarely, if ever, venture outside.
Even more species of spiders were found deeper in the cave, the researchers said: the spindly Kryptonesticus eremita and the tiny, blind Cataleptoneta.
‘Both K. eremita and Cataleptoneta sp. were present in large numbers but were spatially limited to areas where the cave walls were moist and free of gypsum crusts,’ the study said, referring to a calcium mineral.
Metellina merianae, a striped orb-web spider, was the spider megacity’s closest neighbour – researchers said they were larger than average, probably because of the abundant food around them.
For Urák, Sulphur Cave still holds many mysteries about arachnids and the way they can adapt to ‘extreme conditions’ like dingy caves.
After all, a species of spider long-feared extinct, the white-knuckled wolf spider, was recently found on the Isle of Wight.
‘Often, we think we know a species completely, that we understand everything about it,’ Urák added.
‘Yet unexpected discoveries can still occur.’
Get in touch with our news team by emailing us at webnews@metro.co.uk.
For more stories like this, check our news page.