Why does'nt a spider get stuck in its web?

   A spider spins two different kinds of silky thread out of its own body, and it uses both kinds when it makes a web. One kind of silk is sticky. Flies, moths and other insects get caught in it. The other kind of silk isn't sticky. The spider walks on threads of the non-sticky silk when it runs across its web. But just in case the spider slips or makes a mistake, it has an oily stuff on its body that keeps it from getting tangled.