Spider Dragline Perhaps it was E.B. White's endearing children's story of Charolette's Web (1974) that first started an appreciation for the art of spider webs, but people have certainly been borrowing from their design for a long time; just look at Native American dream catchers or a fisherman's net. However we are now getting down to an appreciation for the silk at a molecular level. The silk of the golden orb-weaver spider (Nephila clavipes) is 30 times thinner than human hair. And yet if we extrapolated its characteristics to a size we could picture, say a dragline half the diameter of human hair, scientists calculate this fiber could hold two medium sized people (Valigra, 1999.)

This spider silk is five times as strong as our best comparison, Kevlar that is used in bullet proof jackets (Benyus, 2002, p. 132). Not only does it rival the strength but it is more elastic and lightweight. To make Kevlar we use petroleum-derived molecules treated in a pressurized vat of sulfuric acid at temperatures of several hundred degrees Fahrenheit (Benyus, 2002, p.135; 2001). Using conventional manufacturing techniques we may create many amazing products; however, in the balance we require extreme amounts of energy and create bi-products that are often hazardous to handle, store and dispose. The spider manages to make its superior fiber at body temperature, without requiring high pressures or corrosive acids (Benyus, 2001).

It is difficult to underestimate the breadth of new applications that would be enabled if humans were to be able to produce a material with properties approaching those of spider silk. In addition to being strong spider silk is also highly elastic, a combination that is rare in one material (Benyus, 2001). Silk can actually stretch 40 percent beyond its original form and bounce back. That is 30 percent further than our stretchiest nylons (Benyus, 2002, p.132; 2001). Dupont researchers say that compared to current steel cables currently in use, dragline spider silk one fourth as thick could stop a jet in flight on an aircraft carrier (Valigra, 1999). As Richard Lipkin reports (1995) "spider silk is so strong and resilient that on the human scale, a web resembling a fishing net could catch a passenger plane in flight. If you test our strongest steel wire against comparable diameter silk they would have a similar breaking point. But if confronted with multiple pressures, such as gale-force winds, the silk can stretch as well; something steel cannot do (Benyus, 2001, 2002). For the spider this is necessary in order to catch its prey which may hurtle themselves unwittingly into the web at top speeds, and then fight for its life to get free. This trampoline effect effectively captures prey while keeping the integrity of the web intact. Therefore it is easy to imagine if that produced at the correct thicknesses spider silk would make a superior material to use on suspension bridges as well as reflecting bullets off vests.

Another fabulous characteristic to add to the list of synergistic qualities of spider silk is its tolerance for cold temperatures. It has to get extremely cold before it becomes brittle enough to break easily. Spider silk's low temperature properties give additional validity to its potential as a superior material for bridge cables, but also has implications for lightweight parachute lines which can often encounter frigid temperatures. Scientists are also dreaming of its applications in smaller elements such as sutures and artificial ligaments (Benyus, 2001) or wear-resistant shoes and clothes (made of "natural fibers") stronger ropes, nets, seatbelts; and rust-free panels and bumpers for automobiles. (Lipkin, R., 1996).

Christopher Viney, researcher of the golden orb weaver says we have to become spiders' apprentices "if we want to manufacture something that's at least as good as spider silk, we have to duplicate the processing regime that spiders use" (Benyus, 2002, pp. 135-6). Indeed it is amazing. Spider silk begins with a liquid protein in the abdomen of the spider. The raw material then travels from this gland through a narrow duct and it is then squeezed out through one of six spinnerets (or minute nozzles at the spider's back end). What goes into the spinneret as soluble liquid protein (a la a lunch of insects) "emerges an insoluble, nearly waterproof, highly ordered fiber" (Benyus 2001).

Each spider can construct multiple types of silks, some for structure, such as the dragline, used for repelling and framing a web; other silks are for stickiness, cocoons, mating, and more. However, all of our current scientific knowledge comes from studies of only two kinds of threads spun by fewer than 15 species of orb weavers, a subset that makes up only one tenth of more than 40,000 spider species. Certainly it begs the question, could there be an even better silk out there? In deference to this question Viney admits that most research begins with what is easiest, what others have already done, or the simplicity of care of the organism. "But yes there is probably a tougher, stronger, stiffer fiber being produced right this minute by a spider we know nothing about. A spider whose habitat may be going up in smoke" (Benyus, 2002, pp.138-40).

Biomimicry is more than learning about the tiny workings of nature and looking at each of the parts; we must also look at the entire organism and the systems it is a part of. Looking to nature for solutions is not simply about having a better material at our disposal but also learning the lesson that we need to maintain ecosystems as a library of ideas. Both the potential new material and the side effects of its production are of equal importance. In using biomimicry as a paradigm, the solutions and the resources are of utmost importance, and they are one in the same.