New spider produces world’s largest web and strongest natural material

27/09/2010 14:11:37 Giant orb spiders from Madagascar use the toughest biomaterial to cast webs across rivers
September 2010. Scientists from the United States and Slovenia have discovered a new spider species from Madagascar that makes one of the largest known webs and suspends the giant webs across rivers and lakes. The spiders achieve this feat by using the toughest -most energy absorbing - silk ever discovered , tougher than any other known biological, and most man-made, materials.

The international team of scientists consists of Ingi Agnarsson, Assistant Professor and Director of Museum of Zoology at the University of Puerto Rico, Matjaž Kuntner, chair of the Institute of Biology at the Scientific Research Centre, Slovenian Academy of Sciences and Arts, and Todd Blackledge, Associate Professor of Biology at The University of Akron.

Largest webs up to 25 metres wide!
In the Journal of Arachnology paper, Kuntner and Agnarsson use morphology and DNA evidence to show that the spider, named Caerostris darwini, is a new species previously unknown to science and to describe its unique web and habitat. The spider, named in honor of Charles Darwin 200 years after his birth and precisely 150 years after publication of his Origin of Species, builds one of the largest orb webs ever described and suspends those webs across rivers and lakes, spanning bodies of water up to 25 meters wide.

World's toughest natural material
In the concurrently published PLoS ONE paper, Agnarsson, Kuntner and Blackledge report on the testing of material properties of C. darwini silk. Knowing the unique web gigantism in C. darwini, the authors predicted that such unusual webs would be spun using extraordinary silk. Here, they demonstrate that the prediction was correct. Spider silks combine high strength with elasticity, and are therefore already exceptionally tough-i.e. able to absorb three times more energy than Kevlar before breaking. However, C. darwini silks prove to be about 100% tougher than any other known silk. C. darwini thus produces the toughest biological material known.

Darwinian
These scientists believe extreme web architecture and silk properties likely coevolved. "The ancestors of C. darwini were able to occupy a novel niche through a combination of new web building behavior and new silk qualities", says Agnarsson. "The species may become a model for evolutionary studies, and thus its name after Charles Darwin is very appropriate", adds Kuntner. Precisely why C. darwini evolved such unique webs and silk and how they use their giant riverine webs is currently being investigated by the team through a grant by the National Geographic Society.
The findings were published in the Sept. 15/16 issues of the journals PLoS ONE and Journal of Arachnology.