Image Gallery: Spider silk production
Spiders use silk for many purposes - to protect their young, catch food, make homes and move around. They are the only animals which use silk in almost every part of their daily lives. The original spiders, represented today by the primitive, segmented, mesothelid spiders, had eight pairs of silk spinning organs or spinnerets placed under the middle of the abdomen (Mesothelae). In mygalomorph and araneomorph spiders the spinnerets have moved to the end of the abdomen (Opisthothelae). In these spiders the anterior median spinnerets (AMS) are either no longer present or remain in some araneomorph spiders as a modified spinning structure called the cribellum. Mygalomorph spiders have four or six spinnerets, compared to six in most araneomorphs.