It’s hard to overstate how amazing spider silk is. It’s stronger than steel by weight, able to keep its strength at absurdly high temperatures, can take more punishment than Kevlar, and we still haven’t quite figured it out. To do so, we keep going back to the source. For that you have to knock out a spider.
Spider silk comes from little nozzles on spider abdomens called spinnerets (but not all spiders spin silk). Each large spinneret is a bed for hundreds of smaller spinnerets that extrude a protein slurry, which binds together into silk. That slurry — called “dope” (because it is) — sits inside the spinnerets and is a cocktail of complex proteins that give each strand its specific structure. That structure is what makes spider silk so strong.
Through processes we don’t fully understand, the proteins in spider silk align themselves like the molecules in a crystal would on their way out of a spinneret. Tightly packed together, the outer “sheath” of the silk strand becomes rigid and tough while the core of the strand remains more gooey like the original slurry. It’s a complex structure similar to so-called “meta-materials,” which combine materials together for better performance.
Spiders can rapidly and reliably produce nature’s very own bungee cord.
It makes sense then that we’ve tried to get our own kind of spider silk on the market. In 1937, we invented nylon, which is produced when small chemical units join together to form longer molecules like spider silk does. In 1963, we revolutionized bulletproof vests with the invention of Kevlar, a version of nylon that can really take an impact (much like a spider’s web can from errant flying insects or your face). In 2002, a Canadian biotech company announced that it has successfully implanted spider genes into goats, and were able to extract spinnable spider silk proteins from their milk.
But the mass production of spider silk still eludes us. To get the good stuff, you have to go to the source:
This is a golden orb-weaver spider and she is ready to donate some of her silk. While this silk harvesting looks like a fairly tortuous set-up, the female is first sedated with carbon dioxide and then pinned down harmlessly (this is the same tactic we use when artificially inseminating queen bees).
A single silk strand is pulled from the abdomen and then placed with a touch of glue on a rotating spool.
In one “reeling” a large female golden orb-weaver can produce 30-80 meters (100-260 feet) of silk! After she is done, the spider is released to feed and relax.
Orb-weavers can produce half a dozen different kinds of silk that we know of including silk for wrapping prey, rappelling, encasing eggs, and web construction.
For now, harvesting silk this way isn’t very efficient. For one, a large-scale spider silk operation would have to house millions upon millions of spiders in a facility to make any kind of profit, which means getting around that whole rampant-cannibalism-when-spiders-are-too-close-together thing. For now, it seems like the way to take advantage of the silk’s truly super-human mechanical properties is to keep trying to mimic what nature has spent millions of years crafting (which we are certainly trying to do). It will be a while before we are true web-slingers.
You can watch the full video of the silk harvest from the Oxford Silk Group here.