The Silk Factory
More elastic than nylon and stronger than steel, spider silk has been at the core of arachnids' eons of prosperity. Spinning glands produce the proteinaceous stuff, which spiders let out like kite string from abdominal spigots-combing multiple strands into a single, solid thread. For different uses-dragline, web frame, egg case, retreat, or bug trap-threads may emerge thick or thin, wet or dry, sticky or woolly. The common orb web gets some of each.
The Spining Glands
1. Piriforms: They form attachment disks of fine silk that strengthen the bond between two threads.
2. Aciniforms: Aciniform fibers form swathing, the inner cushion of egg sacs, and the woolly silk used in stabilimenta-white bands or circular patterns that adorn some webs-whose functions are debated by scientists.
3. Ampullates: They produce the threads that form the orb web's scaffolding.
4. Aggregates: Unique to orb weavers and relatives, aggregates yield the glue that makes the sticky spiral sticky.
5. Flagelliforms: Also only in orbweaving species and their relatives, these glands produce the axial threads of the sticky spiral.
6. Cylindricals: These female glands provide the fabric for cocoons.