Sunday, September 27, 2009


Be warned, arachnophobes: this post is about spiders - or more specifically, spider silk. Gossamer has made the weird news again, this time for a special project undertaken by a British art historian and an American fashion designer living in Madagascar: harnessing spiders to produce silk assembly-line style. Four years ago, they began hiring locals to capture 3,000 spiders a day and to gently attach the threads from the spinnerets of two dozen at a time to spools that would collect up to 400 yards from a single spider. The 24 threads were hand-twisted into one and joined into 96-thread strands that were then woven in a loom with traditional Malagasy motifs.The drawbacks included the cannibalistic nature of the spiders, their status as an occasional snack in that country, and the weather (too cold and the spiders wouldn't spin; too humid and the silk was too viscous to be used). Spiders that didn't die in production were released back into the wild. The result, on display at the American Museum of Natural History in New York, is a 11' x 4' textile (pictured) that has been woven entirely with the saffron-colored silk of 1 million female orb weaver spiders!
Gossamer is a protein fiber with which spiders create webs to catch prey, nests for themselves, or coccoons to protect their young. They can also use it to suspend themselves, drift on the wind, or sustain themselves when food is scarce. Gossamer is as strong as Kevlar, can resist the stress of high-grade steel, can stretch to 140% of its length without breaking, and can hold its strength to -40 degrees Celsius - all of this despite being incredibly lightweight (a spider silk that encircled the globe would weigh less than a pound). A single spider has 2 to 8 spinnerets (pictured in close-up) from which they can spin several different kinds of silk to suit various purposes. Webs or threads have been used on a small scale to treat wounds, catch fish, make crosshairs for optics, and help in mammalian nerve regeneration. Because of its unique properties, there has been an interest in producing or duplicating spider silk commercially.
It is to this end that scientists are provoking strange news stories:
  • 8/21/00 A Canadian company has genetically engineered goats with spider genes so that their offspring of nanny goats will produce milk containing spider web protein. The "silk milk" will be used to make a fiber they are calling "Biosteel," from which they will manufacture - among other things - artificial tendons and ligaments, and sutures for use in eye and neurosurgery.
  • 4/28/08 German researchers are getting closer to producing artificial spider silk after making a spinneret that mixes the right ratio of proteins at the right time to create a biodegradable synthetic filament for use in bulletproof vests, as fishing line, and for medical sutures.
  • 4/24/09 Physicists in Germany have made spider silk 3 times as strong by layering it with zinc, titanium, and aluminum. The metal atoms coat the silk, but ions also penetrate the fibers and react with the proteins.
  • 6/19/09 American researchers have determined that spider silk reacts very much like biological muscle, for instance producing strong contractions in response to humidity, which opens up possibilities for biomedical and robotics applications.
    9/20/09 Scientists suggest several reasons why some spiders decorate their webs, debunking earlier claims that the stabilimenta reinforce the webs and unwilling to allow that they are done for aesthetic reasons alone.
And I will end on a personal note. For my nephew Ross's 10th birthday on the 17th of this month, I sent him a remote-controlled tarantula. He was delighted and said, "I will scare everyone, including myself, with this!" I made him promise not to scare my sister, though, and I hope she made it through this post without cringing. Only male tarantulas have spinnerets, by the way, so that they can produce a web as part of the mating process.

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