Silken Steel

by | Oct 15, 2017 | Creation Moment, Times of Restoration

Job 8:14, describing the man who forgets God, says, “His confidence is severed, and his trust is a spider’s web.” The implication is that a spider’s web is fragile. To anyone who has swatted away a cobweb with no more effort than it takes to swat a fly, this is true. To the fly, however, it’s not the aptest metaphor.

For its weight, spider silk—the raw material spiders make to build webs—is as strong as steel, but far more elastic. This has inspired scientists to try to harness its tensile strength: Bulletproof vests, aircraft, and artificial tendons are all possible applications. Spider silk could soon compete with carbon fiber and other lightweight materials.

The stickiness of the silk comes from tiny droplets of glue, but the spider spins non-sticky strands as well, which it navigates carefully to avoid being entrapped in its own web. A spider that waits on the perimeter of the web might lay a non-sticky strand running to the center, giving it quick access to any struggling prey. For added effectiveness, the web is electrically conductive, allowing it to “reach out” and grab flying insects, which often carry a static charge.

Producing silk is taxing for a spider. It has to replenish the protein it expends by catching more prey and even eating its own web. The web loses its stickiness after a short time and needs to be replaced, so it’s an efficient method of recycling and maintenance. In some cases, the work is shared; in 2007, spiders in Texas combined forces to build a single web that measured 200 yards across.

The classic spider web is built by “orb weavers” and features radial symmetry. Orb weavers use their own bodies to measure the distance between each strand of silk. But other types of webs exist too: Funnel webs, sheet webs, and tangle webs all entrap prey or conceal the spider lying in wait.

Some orb-webs contain a web decoration, or stabilimentum, at the center. The purpose of the stabilimentum is debated; it may camouflage the spider at the center or make it appear larger. Alternatively, it may make the web visible to large animals like birds, which would otherwise collide with the web and destroy the spider’s hard work. A recent theory claims that stabilimenta reflect ultraviolet light, attracting prey that seem to be drawn to similar wavelengths reflected in flowers. Perhaps the most mysterious stabilimentum is built by Cyclosa species, which create large, spider-shaped decorations out of the remains of their prey.

One good way to find spiders that don’t spin webs is to go outside on a summer night with a headlamp; spiders’ eyes will reflect the light like tiny diamonds, especially around the bases of trees. You’ll be surprised by how many you see, and if you can overcome your aversion to them, you may have found yourself a hobby. As E. B. White said, “Once you begin watching spiders, you haven’t time for much else—the world is really loaded with them.”

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