|
Wonder Webs Spider webs are more than homes, and they are ingenious traps. And the worlds best web spinner may be the Golden Orb Weaver spider. The female Orb Weaver spins a web of fibers thin enough to be invisible to insect prey, yet __1_tough_ enough to snare a flying bird without breaking. The secret of the webs strength? A type of super-resilient __2_silk_ called dragline. When the female spider is ready to __3_weave_ the webs spokes and frame, she uses her legs to draw the airy thread out through a hollow nozzle in her belly. Dragline is not sticky, so the spider can race back and forth along __4_it_ to spin the webs trademark spiral. Unlike some spiders that weave a new web every day, a Golden Orb Weaver __5_reuses_ her handiwork until it falls apart, sometimes not for two years. The silky thread is five times stronger than steel by weight and absorbs the force of an impact three times better than Kevlar, a high-strength human-made __6_material_ used in bullet-proof vests. And thanks to its high tensile strength, or the ability to resist breaking under the pulling force called tension, a single strand can stretch up to 40 percent longer than its original _7_length_ and snap back as well as new. No human-made fiber even comes _8_close_. It is no __9_wonder_ manufacturers are clamoring for spider silk. In the consumer pipeline: High-performance fabrics for athletes and stockings that never run. Think parachute cords and suspension bridge cables. A steady __10_supply_ of spider silk would be worth billions of dollarsbut how to produce it? Harvesting silk on spider farms does not __11_work_ because the territorial arthropods have a tendency to devour their neighbors. | 
