Monday June 18, 2018 Q&A

A spider’s silk thread is proportionally:


1 more resistant than steel

2 heavier than lead

3 more radioactive than radon

The correct answer is: 1. more resistant than steel.

They may not be very popular, but spiders are fascinating creatures in so many ways. Scientists have also taken a special interest in them. Not only do spiders play an important role in our ecosystem by regulating insect populations, but they also spin thread with exceptional properties, which is why this thread is one of today’s most studied materials. It is ultra-resistant – up to five times more resilient than steel and ten times more so than kevlar, according to some sources. It’s also remarkably elastic, very light, extremely thin and smoothly crafted.

Spider silk may one day have applications in textiles, sports equipment, bullet-proof vests, surgical sutures and dressings, musical instrument strings, traction cables, fiber optics and much more. Just recently, for instance, the University of Geneva announced that researchers there had successfully encapsulated a vaccine into a spider silk microparticle (see the press release). While spider silk is very difficult to mass produce, some companies have managed to create a synthetic version and started marketing it. But we’re still a long way from being able to do what those eight-legged creatures can.

The production of natural silk is a very complex process. Spiders basically have tiny little factories inside them. It all starts in their silk gland – dubbed the spinneret – which is located on the back of their abdomen and produces the proteins that form the basis of the thread. These proteins, which are essentially fibroins and sericins, become intertwined in such a way as to create both hard crystalline segments – in the form of beta sheets – and less organized and more flexible amorphous segments. It is the interplay between these two features that makes spider silk both remarkably resistant and extremely elastic.

Eight types of thread

The proteins secreted by the silk glands are initially stored in liquid form in the spider’s abdomen. This raw material then becomes structured and solidifies as it passes through the secretory section of the gland, in the form of a maze of ducts that draw out the water. The ducts then taper and end with a spigot, a small protrusion that leads to the outside. That’s where the tiny fibers used to spin the thread emerge.

Depending on what they’re going to use it for, spiders can produce up to eight different types of thread, each from a different gland. They can vary in thickness, length and stickiness depending on the purpose: the spider may want to catch prey, imprison it after capture, build the base or the center of its web, mark out its territory or move around, create incubator sacks for its eggs or weave a shelter.

Watch these videos to learn more: