Why Do Spiders Spin Webs?
A spider’s web serves as its home, as well as a trap. Spiders produce silk threads to build their webs. A spider spins its web out of two types of silk thread. One kind is sticky, and is used to catch the insects a spider likes to eat. The other kind of thread is non-sticky.
The silk is produced in silk glands with the help of the spider’s spinnerets. Spinnerets are special organs that allow the spider to decide what type of thread it needs for the web. The threads a spider uses to construct its web begin as liquid, but they dry quickly in the air.
When a spider begins a web, it releases a silk thread. It anchors the thread to a branch, a corner of a room, a door-frame, wherever it builds its web. As the spider moves back and forth, it adds more threads, strengthening the web and creating a pattern. Lines that go from the center of the web outward are called “radial lines.” They support the web. Threads that go around and around the web are called “orb lines.”
A spider is careful to walk only on the non-sticky threads. Some spiders lie in wait for their prey in the center of the web. Others hide in a nest close-by the web. When an insect blunders into the trap, the spider is able to feel the web vibrate. Then the spider rushes out and captures the prey. Many spiders build a new web every night. Not all spiders use webs for food, however. Some don’t build webs at all. Other spiders chase their prey.