Monday, 2 July 2012

DESIGN or CHANCE ! SPIDERS ...............

SPIDERS catch our imagination in many ways and strike fear into many a heart . BUT take time to consider the wonder of spiders ........a) They produce one of the strongest materials in the world b) Their silk is stronger than steel but can be stretched by more than a third and then return back with no damage c) Their silk can withstand extreme fluctuations in temperature and be ...stretched to a point without snapping . CHANCE or DESIGN ? 
Spiders : The material inside a spider's body is a water soluble liquid which is extruded through a tapering duct to emerge as a water resistant silk . The strands consists of four concentric tubes of different material with different properties . The one under the outer silk has fibres spiralling it in both directions . The nano fibres contain flat nano crystals .
"Spiders silk is one of the strongest materials on earth ."
New Scientist , 24th April 1999 , page 38 .

Spider silk is stronger than steel , yet it can be stretched by more than one third and recover without distortion . Spiders webs do not dissolve in the rain . That means that the protein is insoluble . But in the spider it starts by being ...secreted from a little gland into a bulbous sac . The sac's contents are liquid , so the protein must be soluble . Then it comes out as an insoluble solid .
New Scientist 7th May 1994 .

The web of the Orb spider is mainly composed of two types of thread , a framework of dry radial threads upon which is laid a single wet captive spiral .
Nature 12th January 1995 page 146 .

David Knight of the University of Oxford and his collegues tested strands of silk from the large Orb weaving spider NEPHILA EDULIS at temperatures between minus 60 degrees celsius 150 degrees celsius . Knight found that over the entire temperature range the threads could stretch by at least 20 percent before snapping .
New Scientist 22nd January 2005 page 19 . 

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