How it happens6:56Why the world's largest web surprised a scientist
Serban Sarbu thought he had seen it all until he entered a pitch-dark cave located on the border between Albania and Greece.
In the so-called Sulfur Cave, Sarbu and a team of researchers discovered a thriving ecosystem, home to more than 111,000 spiders entangled in the world's largest web.
“Finding so many spiders in one place in the cave was the first surprise,” said Sarbu, a cave scientist. How it happens presenter Neil Koksal.
“So [then]you ask yourself, “Why are they there?” What actually keeps them alive?”
The opening was recently published in the journal “Underground Biology”.
Caves, he explains, are usually devoid of life. No light means no photosynthesis, so there are no green plants and very little organic matter for animals to eat. According to him, any cave creatures are often small, blind and slow, so they try to save all the energy they can.
Why are there so many spiders?
According to Sarbu, the unusual abundance of life in the cave is due to its sulfur-rich environment.
In caves such as this, there is an opportunity for microbes to live, using the chemical energy generated by the oxidation of hydrogen sulfide.
Besides spiders, the cave is also home to other creatures such as centipedes, scorpions, beetles, bats and chironomid insect larvae.
When these flies mature, many adults are caught in the spiders' sticky webs.
“They get trapped and then the spiders come out of their little funnel holes and catch the flies and eat them,” Sarbu said.
According to Sarbu, the huge network is not the product of joint planning. Instead, each spider builds its own web, but because the food is concentrated, the webs were built so close together that they eventually merged into a huge multi-layered structure.
Over time, the old networks collapsed under their own weight, and new layers formed on top of them.
“I don't think the spider has any intention of building a colonial web. They don't get together and say, 'Okay, let's build a big web together and one will help the other,'” he said.
The network covers about 1,140 square feet, which is roughly the size of a small home. It hangs in a low, narrow passage among a network of limestone rooms carved by the Sarantaporos River.
More amazing discoveries
Even more remarkable, Sarbu says, the researchers found two species of spiders coexisting in a huge funnel web: about 69,000 individuals. Tegenaria domesticaor common house spiders, and 42,000 Prinerigone Vagana.
Typically larger spiders prey onthere are smaller spiders, makes this peaceful coexistence unprecedented, evolutionary biologist Lena Grinstead, who was not involved in the cave study, told The Associated Press.
“Very often, if you have spiders in close proximity, they will fight and end up eating each other,” said Grinstead, a senior lecturer in zoology at the School of Biological Sciences at the University of Portsmouth in the UK.
Tegenaria domestica more than Prinerigone to wanderand in this case they live together.
“Sometimes we can see that if there is a lot of food, they become less aggressive,” Grinstead said.
She noted that darkness can impair spiders' vision, reducing their aggression.
“Spiders generally don't see things very well… including these two species,” she said.
She says the two species may cooperate a little in network building, but are unlikely to cooperate in other behaviors, such as prey capture or offspring care.
What was equally astounding to Sarbu was the attention the discovery received from the public.
“It’s very hard to believe because I’m used to people liking dogs, cats, penguins, whales and many other things,” he said.
“Most people, when they see one spider, they start screaming. But here we have 100,000 spiders and everyone wants to know about them – I find it hard to believe.”
