A spinner's secrets.

Slinky These motifs are rich in the amino acids glycine and proline and help give silks their stretchiness. Zipper Other glycine-rich regions zip together, forming helixes that confer flexibility. Lego These regions contain repeating alanines that lock together, adding toughness. A living textile factory The golden orb-weaver has seven kinds of silk glands (distinguished left, by color), with each generating a specific liquid of silk proteins, or spidroids, that are chemically modified, solidified into a fiber, and extruded from a spigot. (Only one of the many glands of each type is shown.)