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The spider’s web is an evolutionary marvel. While other animals risk injury and expend energy each time they hunt, the clever spider spins her iconic orb-shaped web, then waits. She exposes herself to no risk and once the prize is trapped, the pickings are easy. But the web itself is not an easy thing to create. The conditions need to be just right for a spider to set her trap.
Making the Silk
Spider silk is one of the strongest materials known to man. Pound for pound, spider silk is stronger than steel. The spider creates her silk internally, through a complex system of protein creation and dehydration, she generates an “acid bath” inside her body, enriching the silk proteins. The substance then passes through a duct and out of the spider’s spinneret, the silk spinning organ.
For a spider to span distances greater than her body length, she needs a little help. She uses wind to carry her from the starting point to the end point. She spins the first strand of silk, which sticks to the tree branch or wall where the web starts, then she sails on the wind, spinning silk as she goes. She guides the silk with one of her rear legs, which she already has coated with a substance from her mouth to prevent the silk from sticking to her.
The Bridge Thread
The bridge strand is a super-strength, thick strand of silk that forms the basis of the entire web. She spins this strand first. Those who’ve walked through a spider web spanning two trees will be aware of how far spider webs might stretch, but spinning a web between two closely spaced trees is no big accomplishment for a spider. They can spin webs across rivers.
An Economic Builder
If the spider is unable to attach her bridge thread to a second surface, she’ll eat the strand, recycle the proteins and start again. Once she’s landed on a second surface and has her bridge thread in place, she may leave it in place overnight. This is so she can produce more silk insider her. When she returns, she spins a number of thinner threads, the same length and width as the bridge thread, but not the same thickness. These threads are similar in function to the spokes of a wheel. The number of spokes vary according to the breed of the spider. Some spiders even spin three-dimensional overhanging webs. Black widow spiders (Latrodectus) spin webs that overhang, and rely on a cross-hatch pattern.
Power of the Orb
As well as the silk being strong and highly resilient to damage, the classic orb shape of the typical spider web is key to its strength. The intricate arrangement of lateral strands, interwoven with linking strands make the web resistant to damage. Once a bug is caught in the web, it will struggle and potentially may weaken some strands. But after eating the bug, the spider simply repairs the weakened strands and resets her trap.
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