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How do spiders spin their webs?
To spin a tale about the spider, member of the species arachnid, we must first examine the common thread that ties them together...the way they produce the silk they use to weave their webs, as well as other contraptions, to suit their particular needs.
Production of silk begins in certain glands located in the abdomen, or belly, of the beast. Spinning organs at the tip of the abdomen, contain many tiny holes, and function much as a sieve, through which the silk is pressed. The silk strained through is in liquid form, but immediately takes on a solid form, much like cotton candy does, when exposed to air.
Even the webs the spider spins differ greatly, depending upon the factors listed above. The most common of all webs we see is the wheel-shaped web. Less common are the so-called "sheet" webs, which blanket surfaces with a funnel, or dome like shape. The trap-door spiders burrow out their webs, and complete them with built-in chutes, through which their unsuspecting guests fall through, right onto the spider's plate. The web we see least often, is the air-tight, bell-shaped home some spiders build...probably because it is completely submerged in water!
In short, startled spiders can be entangled in their own webs, in the same manner as their prey. Generally speaking, however, the spider avoids this deadly mishap, by differentiating between the various types of silk it produces, and by knowing its home turf.
When the spider weaves its sticky, insect-catching type of web, it builds into it safety threads of the non-sticky variety, upon which it traverses without being snared. Its nimble, highly sensitive feet orient the spider about its new home, and past the potential pitfalls, to which its prey fall victim. Unless, of course, something, or someone, startles the spider, in which case all bets are off, and the parlor game is over.
Enlarge the picture below for a better look....
Information supplied by: http://www.coolquiz.com/trivia/explain/docs/spider.asp