Arachnophobes look away now: The world's biggest spider web stretches more than 80 feet across river



Arachnophobes, look away now.



For scientists have discovered some of world's biggest and strongest spider webs spanning over a river in Madagascar.

Created by Darwin's bark spider, a newly identified species, the giant webs are made of the world's strongest known biological material.

Shown here in these pictures the orbs are the world's largest webs of any single spider, according to new studies.

A giant web made by Darwin's Bark Spider spans over a river in the Andasibe-Mantadia National Park in Madagascar

Zoologist Ingi Agnarsson of the University of Puerto Rico and colleagues have found Darwin's bark spider webs as wide as 82 feet in the Andasibe-Mantadia National Park.

Despite spinning webs of Spider-Man-like size and strength, the Darwin's bark spider uses them to feed mainly on small fry-insects such as mayflies and dragonflies, the team found.

The weavers of the largest Darwin's bark spider webs are almost always female, said Agnarsson.

Juvenile males also weave spider webs, but once they become adults, they abandon this behaviour and instead direct their energies solely to sex.

A park ranger near standing below one of the giant webs, some of which were up to 80 feet wide

For survival, the Darwin's bark spider relies in part on its mottled, jagged appearance, which camouflages the spider against trees and-along with Charles Darwin-inspired its name.



A female Darwin's Bark Spider, a newly identified species

The species is known to exist only on the island of Madagascar, off Africa's southeastern coast.

Darwin's bark spider webs are made out of two basic kinds of silk, Agnarsson explained.

'Dragline' silk is used to create the supporting strands that anchor the endpoints of an orb web to tree branches overhanging rivers or lakes and forms the radial threads in the web.

Stretchier, stickier silk is used to create the spiral that captures prey.

When an insect flies into the web, it becomes stuck, and its struggles causes the silk lines to vibrate, alerting the Darwin's bark spider.

The spider then crawls to the captured insect, and envelops it in a silk cocoon to eat at its leisure.

An analysis of the Darwin's bark spider's silk indicates it's the toughest biological material discovered to date.

''Tough' means the ability to absorb energy before breaking, and results from a combination of strength and elasticity,' National Geographic News quoted Agnarsson, as saying.

Scientists wondered how Darwin's bark spider creates webs wide enough to span bodies of water.

One of the rangers 'said the spiders do a Tarzan swing, like they hang down on the silk and swing over. We really, really tried to verify that, but it turned out to be false,' said Agnarsson.

He hopes that studies of the species will help shed light on mysteries of spider silk.

The findings appear in the Journal of Arachnology and PLoS ONE.



Prey caught in the web which is made form the world's strongest known biological material

The research team from the University of Puerto Rico inspect the spider webs and terrain



