If you have ever swatted a spider web away from a dusty corner of the house, congratulations—you have unknowingly dismantled one of the toughest materials known to man. The silk which spiders use to spin their webs and capture prey is five times stronger than steel, yet lightweight and more flexible than rubber. Because of these remarkable properties, scientists have been trying for years to produce large quantities of synthetic spider silk in the lab. They have notoriously run into problems, however, partly because experimental data about spider silk structure has been missing. Now, Hannes Schniepp and his team have shown that spider silk gains its strength from thousands of microscopic ‘nanostrand’ fibers that stick together, much like a wire cable. The group examined the silk of the brown recluse spider at the molecular level with an incredibly sensitive microscope, which allowed them to visualize structures smaller than a fraction of a millimeter. Using this technique, they observed that the nanostrands—only 20 millionths of a millimeter in diameter—have a distinct ribbon shape and run parallel to each other lengthwise to form each silk strand. This structure is able to withstand much more force than a strand made up of a single fiber, giving spider silk its characteristic strength. Uloborus uses an organ that isn't found in many other spiders, called the cribellum, consisting of up to two plates covered densely with silk-outflow spigots, which narrow to about 50 nanometers in diameter. The spinning spigots are the exit points for very long, narrow tubes about 500 nanometers long that carry the silk raw material. The thread thinness comes thanks to the spider's extra-tiny silk glands. "Uloborus has unique cribellar glands, amongst the smallest silk glands of any spider, and it's these that yield the ultra-fine 'catching wool' of its prey capture thread," said Kronenberger, the study's lead author. The duo then noted an action by the spider that seemed to bring on the stickiness needed to capture prey. "The swath of gossamer, made of thousands of filaments, emerging from these spigots is actively combed out by the spider onto the capture thread's core fibers using specialist hairs on its hind legs," said Vollrath. The researchers found that this combing action, combined with a violent pulling on the threads, generates an electrostatic charge. The charge, coupled with the nano-thinness of the filaments, provides adhesion, creating a super-sticky silk for prey capture. The researchers explained that conventionally produced polymer fibers usually have diameters of about 10 micrometers or thicker. Synthetic filaments, they said, could get longer and stronger if they could be manufactured commercially to nano scale. With the structure of brown recluse spider silk identified, scientists are better poised to create synthetic silk fibers. Some potential uses of silk technology gravitate towards the practical, such as lightweight and durable clothing and shoes. Other applications could have broader benefits to society. For example, the German startup company AMSilk recently announced plans to partner with aerospace engineers to develop silk-based materials for airplane production. The proposed airplanes will require less fuel and maintenance than current models, potentially making air travel more affordable and reliable. Managing Correspondent: Benjamin Andreone News Article: Spider silk is five times stronger than steel—now, scientists know why. Science Original Article: Strength of Recluse Spider’s Silk Originates from Nanofibrils. ACS Macro Letters. When spiders moved from the water to the land in the Early Devonian period, they started making silk to protect their bodies and their eggs.[3][5] Spiders gradually started using silk for hunting purposes, first as guide lines and signal lines, then as ground or bush webs, and eventually as the aerial webs that are familiar today.[6] Spiders produce silk from their spinneret glands located at the tip of their abdomen. Each gland produces a thread for a special purpose – for example a trailed safety line, sticky silk for trapping prey or fine silk for wrapping it. Spiders use different gland types to produce different silks, and some spiders are capable of producing up to eight different silks during their lifetime.[7] Most spiders have three pairs of spinnerets, each having its own function – there are also spiders with just one pair and others with as many as four pairs. Webs allow a spider to catch prey without having to expend energy by running it down. Thus it is an efficient method of gathering food. However, constructing the web is in itself an energetically costly process because of the large amount of protein required, in the form of silk. In addition, after a time the silk will lose its stickiness and thus become inefficient at capturing prey. It is common for spiders to eat their own web daily to recoup some of the energy used in spinning. The silk proteins are thus recycled. The tensile strength of spider silk is greater than the same weight of steel and has much greater elasticity. Its microstructure is under investigation for potential applications in industry, including bullet-proof vests and artificial tendons. Researchers have used genetically modified mammals to produce the proteins needed to make this material.