Between one of yesterdays thunderstorms and down pours, I found this spider weaving her web with ferocious speed. It was amazing to watch the fingers pull the tread out of the sac with never a break in the weaving.
During the process of making an orb web, the spider will use its own body for measurements.
Many webs span gaps between objects which the spider could not cross by crawling. This is done by first producing a fine adhesive thread to drift on a faint breeze across a gap. When it sticks to a surface at the far end, the spider feels the change in the vibration. The spider reels in and tightens the first strand, then carefully walks along it and strengthens it with a second thread. This process is repeated until the thread is strong enough to support the rest of the web.
After strengthening the first thread, the spider continues to make a Y-shaped netting. The first three radials of the web are now constructed. More radials are added, making sure that the distance between each radial and the next is small enough to cross. This means that the number of radials in a web directly depends on the size of the spider plus the size of the web. It is common for a web to be about 20 times the size of the spider building it.
After the radials are complete, the spider fortifies the center of the web with about five circular threads. It makes a spiral of non-sticky, widely spaced threads to enable it to move easily around its own web during construction, working from the inside, outward. Then, beginning from the outside and moving inward, the spider methodically replaces this spiral with a more closely spaced one made of adhesive threads. It uses the initial radiating lines as well as the non-sticky spirals as guide lines. The spaces between each spiral and the next are directly proportional to the distance from the tip of its back legs to its spinners. This is one way the spider uses its own body as a measuring/spacing device. While the sticky spirals are formed, the non-adhesive spirals are removed as there is no need for them any more.