"Spider Megacity" Found Inside Sulfur Cave
Language
Reading Level
Listen to Article
Alignment
Researchers have found the largest spider web ever recorded inside a sulfur-rich cave along the Greece–Albania border. The "spider megacity" covers an astounding 1,140 sq ft (105 sq m). This is about the size of a small apartment. This remarkable discovery was revealed by biologist István Urák and his team on October 17, 2025.
A group from the Czech Speleological Society — an organization dedicated to the study and exploration of caves — first stumbled upon the site in 2022. Recognizing its unusual size, they alerted scientists. The scientists visited the cave in 2024 and collected specimens from the web. These spiders were later analyzed by Urák. He later organized his own expedition to what is now called Sulfur Cave to study the web and its inhabitants in greater detail.
"You have to experience it to truly know what it feels like," Urák said.
A closer examination revealed that the web is home to around 111,000 spiders. They belong to two different species. About 69,000 are barn funnel weaver spiders also known as common house spiders. Measuring about 12 mm long, they typically build funnel-shaped webs in dark spaces such as attics or basements.
The remainder are a much smaller species called Prinerigone vagans. They are usually 1.7 to 3 mm long. In Sulfur Cave, these spiders do not build webs of their own. Instead, they live on the larger spiders’ webs and ambush passing insects. These two species do not normally live together. However, they are able to coexist in this cave. That is because the larger spiders cannot see the smaller ones, which barely move in the pitch-black environment.
The scientists believe Sulfur Cave provides an ideal environment for this giant web. It is dark, quiet, and protected from the outside world. Hence, the spiders face few predators or disturbances. The cave’s walls are covered with sulfur-eating bacteria, which support large populations of midges and other small insects. This steady supply of prey lets the tens of thousands of spiders live together without competing for food.
Urák and his team plan to continue studying the cave to learn more about its ecosystem and massive spider colony. They also want to study the spiders' genes to understand how they survive in the harsh, sulfur-rich environment.
"We're just beginning to understand how extraordinary this ecosystem really is — and there’s so much more to uncover," Urák said.
Resources: Livescience.com, Smithsonianmag.com, nbcnews.com
Get the Workbook for this article!
Workbook contains: Article, Reading Comprehension, Critical Thinking Questions, Vocabulary in Context (+ answers), Multiple Choice Quiz (+ answers), Parts of Speech Quiz (+ answers), Vocabulary Game (+ answers)Cite Article
Learn Keywords in this Article
55 Comments
ripclaude1 dayCool!!!! I do like spiders but 111,000 is too much...
arwen_the_elf10 daysi almost had a panic attack reading this
ilovehenrydsaf9 daysYour arachniphobia is that bad? Goodness. I'm sorry about that :(
ekoehler544522 daysamazing
migsyberry26 daysITS SOOOO COOOOL HOW THATS THE BIGGEST SPIDERWEB I HAVE EVER HEARD OF!- migsyberry29 daysVERY COOL! I have a pet spider named Princess she is a tlitlcotl albopilosus.
- ilovehenrydsaf26 daysAww, a spider named Princess?? I love that 😭 I wish I had a pet spider. And a mouse too. I want a mouse named Mr. Boy, like the one will wood has :'3
- migsyberry8 daysThanks. A mouse named Mr. Boy sounds nice. I used to have a mouse named Valentine.
ohhhyeah30 daysI can handle a few but 110,000 is just wrong. Someone needs to hire 1,000 exterminators for that.
hosejypa-175621585135about 1 monthwhy so many spiders
eli9167about 1 monthso disgusting and creepy- ilovehenrydsaf25 daysI think they're pretty neat :(
alishertur007about 1 monthwhen i read that THAT was a common house spider i froze
ihaveauraabout 2 monthsi don't like spiders ahhhhnhhhhhh
hawabyhecufiabout 1 monthThey're cute!!!- ilovehenrydsaf25 daysThey are indeed cute!
