It has been said that you could trap a jumbo jet with spider silk the thickness of a pencil. Spider silk is creation’s wonder material. It combines great strength with great “stretchability.” Dragline silk—the sort of silk used by spiders to hang from high places and build the frames of their webs—is five times stronger than steel of the same thickness. Only one or two very special, very expensive manmade materials can take more strain before breaking.
Spider silk is a composite material. This means it is made from two or more ingredients that are better together than they are by themselves. Each silk strand is made of tiny crystal sheets embedded in a rubbery substance. The rubbery coating provides the stretchiness, while the crystal sheets prevent breaking. A good example of a manmade composite is fiberglass. This consists of glass fibers embedded in a sticky resin that can be molded into different shapes. The end product is stiff, strong, and lightweight—all at the same time. A surfboard made out of fiberglass is lighter, easier to shape, and less prone to breaking than a single piece of wood the same size.
It is even more incredible to think that the spider makes its silk “on the fly.” Orb-spinning spiders can make several different kinds of silk, depending on what they need at the time. Their abdomens are like chemical factories with separate production lines. They can make the dragline silk mentioned already, plus: silk to add a spiral frame on top of the main frame; sticky, moistened silk to capture insects; soft silk to coat egg sacs and prey; hard silk to protect the outside of egg sacs; and silk to cement joints and attachments. If a web is damaged, or if a spider wants to move to another place, it will eat its own silk. This recycling saves a lot of the spider’s energy.
Capture silk is softer and stretches more than dragline silk, but water droplets help pull it back together. Also, the whole web acts like a parachute. When it is hit by an insect, the threads drag through the air. This helps absorb some of the impact energy. The rest of the impact is absorbed by the web’s framework of strong threads.
Scientists have found it very hard to beat what God created in the beginning. They are trying to make spider silk in huge quantities, and hope to weave very strong, lightweight garments, such as bullet-proof vests. Well, “if you can’t beat ’em, join ’em,” as the old saying goes.
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