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Summary: Spiders spring a trap Page 1 of 1
http://www.nature.com/nsu/nsu_pf/030317/030317-14.html 7/10/2003
Spiders spring a trap
Web silk is a trampoline of soggy molecular helixes.
24 March 2003
Philip Ball
The capture silk spun by spiders contains soggy molecular springs to absorb the
impact of an insect flying into their webs. The finding might help materials
scientists to improve the synthetic fibres used in strong, lightweight, stretchy
fabrics or protective coatings.
If spiders' sticky silk threads were too stiff they would snap when dinner flew into
them; too bouncy and they'd shoot it straight out again. Instead they dissipate
energy by warming up as they stretch. What's more, the fibres are as strong as
Kevlar or steel, thin enough to be invisible to a flying bug, and extendable to up
to ten times their initial length.
Helen Hansma of the University of California, Santa Barbara, and colleagues hit
on the idea of soggy springs after stretching individual silk molecules with an
atomic-force microscope1. This device contains a fine needle attached to a
cantilever arm.
The researchers dipped the needle into a smear of liquid silk from a common
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