Making a dragline
A front spinneret - the largest spigot produces the spider's safety line, called the dragline. The smaller spigots produce lots of short sticky threads that make a strong attachment point for other silk lines. Photo: © J Thompson.
Different silks are often used sequentially or together. If you watch a huntsman spider moving across a window you may see it apply its front pair of spinnerets (anterior lateral spinnerets, ALS) to the glass, leaving behind a zig-zag patch of silk. This is called the attachment disc and it is made up of numerous, very short threads of silk from the piriform gland spigots. The spider's 'safety line' or dragline (a strong silk from the large major ampullate gland spigots adjacent to the piriform spigots) fuses with the attachment disc silk, giving the drag-line a secure anchor point as the spider walks or drops away, letting out the dragline (under muscular valve control in the silk duct) as it goes.
Silk is often drawn out of the spigots simply by movement of the spinnerets in relation to a fixed attachment point - as in the case of the dragline above. Other examples can be seen during prey wrapping and egg sac construction. Silk is pulled from the aciniform spigots, often in broad swathes, as the spider's legs rotate the prey 'package' or egg sac. The terminal leg claws and bristles also are used to pull out silk and manipulate silk lines during these and many other web building (e.g., combing out cribellate silk) and prey catching activities (e.g., combing out cribellate silk and throwing out sticky swathing silk).
