- Spiders can make different types of silk, depending upon its function. For example, the golden orb-weaver spider has seven kinds of silk glands, with six spinnerets. Some is used for spinning webs, but other types are used for wrapping prey and encasing eggs.
- The webs consist of sticky “catching threads”; radial “spokes” for holding the sticky threads; “bridge threads” that act as guy-lines for holding the web up; “signal threads” that inform the spider through vibrations sensed in the legs that prey is in the web; and “drag lines” for access into the web from her home.
- Spiders are able to determine both the angle and distance of the prey from the center of the web. They are able to determine the prey location using the same basic technique we use to determine the location of the source of sound. Humans use the difference in intensity of sound received by our ears to estimate the relative location. Spiders do something similar based on the intensity of vibrations received, in their case sensed through eight legs.
- Silk can be stronger than steel of the same thickness, can stretch more than rubber, and is stickier than most tape. A typical garden spiderweb is made of 65 to 195 feet of silk.
- Silk has been described as “easily the most remarkable building material on the planet, and it has one source: arthropods.”
- Despite great effort, humans have yet to produce anything functionally equivalent to silk. Through genetic engineering, attempts have been made to duplicate it without success.
So, here's the question I mentioned in the first sentence: How did all of this, the anatomical, physiological and behavioral properties of spiders, evolve by blind, unguided processes. No one knows. Maybe that's because they didn't.
