animals [spiders]

[heyamaqel]

Why spider does'nt stuck on the web?

[bix67]

some of the threads are not sticky and the spider remembers which ones when it pounces on it's prey

[CrazyWolfman]

Basically bix67 has got it, in a conventional orb web there are spokes which all meet in a central point and a spiral which goes around the central point in ever increasing circles. The spiral is sticky and the spokes are not. This is because spiders have several pairs or spinnerets (the things through which the silk is extricated), one pair will produce normal silk and another pair will produce the sticky stuff which is coated over it as it comes out. Although there are often more spinnerets than this (six usually) it all means that the spider can choose which type of silk to spin. Obviously the spider then makes sure it doesn't go treading on the wrong strand.