Spider’s web secrets revealed by scientists

Scientists have unravelled the mystery of how a spider’s web can withstand stresses from raindrops to hurricane winds.

And the first detailed analysis of the mechanical properties of its silk could lead to a blueprint for stronger, stretchier and more elastic materials.

Spiders have been building webs to trap their prey and dangle from caves for 200 million years, thanks to a combination of strength and stretchiness – silk’s characteristic way of first softening and then stiffening when pulled.

A web’s design allows a single thread to break, so the rest of the web remains unharmed.

Engineered structures do not behave that way. If a building, a car or an aeroplane is exposed to large mechanical stress, it typically breaks as a whole.

Spider silk is five times stronger than steel of the same diameter. Each thread is finer than a human hair and is able to keep its strength below –40C. The faster and tighter the strand is drawn, the stronger the silk.

The unique probing of a web, described online in Nature Materials by Professor Jeffrey Yarger of Arizona State University ,found an increase in fibre stiffness in a humid environment.

This is caused by a process known as “supercontraction” that helps the spider to tailor the properties of the silk by pulling and restraining the silk threads and adjusting the water content.

This behaviour, specifically adjusting mechanical properties by adjusting water content, is inspirational from a bio-inspired mechanical structure perspective and could be used in industry for “robotics, sensor technology and other applications”.