Earth Notes: Amazing Spider Silk

Apr 5, 2017

Have you ever looked closely at a spider’s web rimmed with raindrops or frost? So delicate, these marvels might not look like they’re made from one of the strongest materials on the planet. 

Credit Jenny Mackness

But the silk that spiders use for the outer rim and spokes of their webs has the same tensile strength as Kevlar, but is more elastic. And unlike the extreme processing needed to make artificial fibers, spiders produce the silk at ambient temperatures and atmospheric pressure.

Orb-weaving spiders have been around for 400 million years, and long ago perfected their protein-rich silk recipes.  

The protein molecules fit together in the shape of a slinky toy combined with Lego bricks – forming a stretchy structure so tight even boiling water can’t penetrate it. That’s why spider webs don’t dissolve in the rain.

Silk starts as a balled up globule inside the spider’s body and is converted to long, thin strands as the spider pulls it out like floss from its spinneret.

A typical spider can produce seven different types of silk – but none are sticky on their own. The spider adds glue on top, varying the thickness and stickiness depending on whether it needs to catch and wrap prey, fashion a cocoon for its young, or make a miniature zip line to float away from predators.

Next week on Earth Notes, hear about a unique spider housing.