It is very difficult for a human to see a spider descending from the ceiling until it is right in front of his eyes. During the descent, the spider performs light rotational movements – and scientists finally figured out why he does it.
In a study published in the Applied Physics Letters, scientists collected several representatives of the circular spirals (Nephila edulis and Nephila pilipes), also known as “zoltopryads” and “giant tree spiders”. In laboratory conditions, spiders sampled their filaments and then measured the force of their tension using a torsion pendulum, a special device that was used by the British physicist Henry Cavendish 200 years ago to estimate the mass of the Earth. The modern version of the device has the ability to process photographs.
All other fibers that scientists measured (human hair, metal fishing line, carbon fiber, etc.) during twisting behaved like elastic materials, that is, returned to their original shape after twisting and stretching. However, the web, during even a slight twisting, was deformed at the molecular level, which does not allow the material to spring and allows the spider to be able to keep on weight during a careful descent.
The authors of the research believe that the unique arrangement of molecules in the web allows the network to retain its shape, extinguishing the energy of any external influence like a pillow. Engineers can use this property to create materials that will form the basis of special equipment for rescuers and climbers – this kind of depreciation is extremely useful in extreme conditions.