Giant spiders cast webs over river using super biomaterial

Sep 17, 2010
Caerostris darwini, a giant orb spider and namesake of Charles Darwin, weaves a web of tremendous strength and size never before seen. Photo courtesy of Matjaz Gregoric.

(PhysOrg.com) -- The antithesis of the itsy-bitsy spider, Caerostris darwini, a giant orb spider and namesake of Charles Darwin, weaves a web of super strength never before seen, says Dr. Todd Blackledge, Leuchtag Endowed Chair at The University of Akron.

Blackledge, an associate professor of biology; Ingi Agnarsson, Blackledge’s former postdoctoral researcher at UA and current assistant professor and director of Museum of Zoology at the University of Puerto Rico; and Matjaž Kuntner, chair of the Institute of Biology at the Scientific Research Centre, Slovenian Academy of Sciences and Arts, reveal this new species from Madagascar and its incredibly expansive web.

“Darwin’s bark spider or C. darwini,” as it is referenced, makes one of the largest known webs and suspends the giant webs across rivers and lakes, according to the researchers. The scientists say these spiders achieve this feat by using the toughest, most energy-absorbent ever discovered, stronger than any other known biological material and most manmade varieties. They publish their findings in the Sept. 15 and 16, 2010 issues, respectively, of the Journal of Arachnology and the PLoS One interactive open-access journal for the communication of all peer-reviewed scientific and medical research published by the Public Library of Science.

This close-up view of a giant orb spider web spanning a river demonstrates the tremendous strength and elasticity of this type of silk. Photo courtesy of Matjaz Kuntner.

In their paper, Agnarsson, Kuntner and Blackledge report on the testing of material properties of Darwin’s bark spider. The authors predicted that the expansive webs would be spun using extraordinary silk and they proved their prediction correct. First, the researchers considered that spider silks already combine high strength with elasticity, demonstrate exceptional toughness and are able to absorb three times more energy than Kevlar (a high-strength synthetic fiber) before breaking. The scientists prove that Darwin’s bark spider silk is about 100 percent tougher than any other known silk. Subsequently, this spider species produces the toughest biological material known.

Possibilities considered for technological applications

“The incredible toughness of this spider’s silk is an important discovery for two reasons. First, it suggests that these spiders may have evolved a novel mechanism for the production or assembly of their ‘super silk.’ Second, it opens up new technological applications for spider silk that capitalize on C. darwini silk’s truly impressive combination of light weight and high performance,” Blackledge says.

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

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 Darwin’s bark spider 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.

Explore further: Nature collides with James Bond: Newly discovered ant species hides in plain sight

Provided by University of Akron

4.9 /5 (37 votes)

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User comments : 18

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CreepyD
5 / 5 (2) Sep 17, 2010
I've always wondered this, especially in this case. How does the spider get the initial thread to the other side?
I know some use the wind, but sometimes it's done indoors where there is no wind.
Bob_Kob
not rated yet Sep 17, 2010
Ever watched spiderman? Just launches it out.
El_Nose
4 / 5 (4) Sep 17, 2010
i believe most spiders like you said jump with the wind to there destination or simply walk there -- remember there are 'types' of spider silk that spiders produce. Each spider can produce at least three types the strongest strands that support the infrastructure of the web are not sticky so as long as the spider does not get it caught on something they can pull it up. And extra silk produces is digested by the spider.

http://www.chm.br...age2.htm

Corban
not rated yet Sep 17, 2010
This article doesn't even say WHAT makes this spidersilk so much better than others. Is it the protein? Does it weave the threads? Or is it drier or wetter?
AMMBD
not rated yet Sep 17, 2010
so, super silk. what exactly are these spiders hunting?
droid001
not rated yet Sep 17, 2010
they hunting birds I suppose
Sean_W
1 / 5 (2) Sep 17, 2010
so, super silk. what exactly are these spiders hunting?


Missionaries.
panorama
5 / 5 (1) Sep 17, 2010
so, super silk. what exactly are these spiders hunting?


Missionaries.


And research scientists...
Yevgen
5 / 5 (4) Sep 17, 2010
they hunting birds I suppose


Actually it is insects, but quite big once, like mayflies:
http://news.natio...x450.jpg
Mayday
1 / 5 (1) Sep 17, 2010
Many spiders can send out a nearly weightless feeder line that can float on the air (even indoors, like dust). Outdoors they can be several meters long and under the right conditions can allow the spider to literally take flight (even large spiders are very, very light).

According to the size of the tripod in the photo, I don't see this web as any larger than some of the Banana Spider webs I've seen in Florida. Their webs often exceed a meter in diameter. They should be just coming into their big season right now. I've seen thicker strands from thier webs that would be quite difficult to break with your bare hands.
dirk_bruere
not rated yet Sep 17, 2010
Strength?
HealingMindN
not rated yet Sep 17, 2010
Is the web as big as a spider goat's?

Meet Spider Goat - the DNA-enhanced web-flinging nanny that may one day knit bones

Professor Lewis and his team at the University of Wyoming have successfully implanted the silk-making genes from a golden orb spider into a herd of goats and are now, finally, producing one of nature's strongest products in useable quantities...


http://www.news.c...67617374

I wonder if they tried this on people yet? Would there be side effects like females eating their mates?
Parsec
5 / 5 (1) Sep 18, 2010
Many spiders can send out a nearly weightless feeder line that can float on the air (even indoors, like dust). Outdoors they can be several meters long and under the right conditions can allow the spider to literally take flight (even large spiders are very, very light).

According to the size of the tripod in the photo, I don't see this web as any larger than some of the Banana Spider webs I've seen in Florida. Their webs often exceed a meter in diameter. They should be just coming into their big season right now. I've seen thicker strands from thier webs that would be quite difficult to break with your bare hands.


The size is one thing, the ability to span a stream 75 feet wide is quite another. Do Banana spiders have webs that can do that? That are also 100 percent stronger than any other know spider species?
yyz
not rated yet Sep 18, 2010
Discussing how Darwin bark spiders construct these enormous webs, the Nat Geo site notes:

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

"Since then, team member Matjaz Gregorič has discovered the spider's trick and will describe it in a future science paper."

I guess we'll have to wait for the definitive answer (but I have a few alternatives in mind). Anyone else?
Ravenrant
not rated yet Sep 18, 2010
Large spiders don't float in the air. Since it sounds like jungle to me it might be likely the canopy touches above the streams. They could also drop down and let the stream carry them across. Once they let out enough line wind blows it like a sail too.
Djincs
not rated yet Sep 18, 2010
the spiders makes this aero travels when they are young and small, the house spiders cant do it, and when they make their web they walk to the different points, and for making such web(accros the river) they just have to wait for the wind to blow in the right direction, then they let the line when it bind to something yhey can go accros.
Mayday
1 / 5 (1) Sep 19, 2010
I was just out for a ride along the Atlantic coast in south Florida and saw a few Banana spider's webs that easily spanned 50 feet. There are many that crossed between trees high above the two-lane coastal hiway. I'm sure someone who went out and really looked could find webs spanning longer distances. Right now, there are hundreds of these specimens in the treetops. These folks need to get out more often!
adamshegrud
not rated yet Sep 19, 2010
...has discovered the spider's trick and will describe it in a future science paper."...


Even science papers have cliff hangers
Lame
what a tease