How Spiders Build Webs in Space
By: Gunnar De Winter
Tags: Science, Space, Biology, Animals, Engineering

How Spiders Build Webs in Space

Spiders on the International Space Station spin odd webs, and it teaches us something new

(Pixabay, Couleur)

Gotcha!

Not all spiders make webs, but most of us can’t help but think of cobwebs when we think of spiders. The beautiful silky homes of our eight-legged friends are marvels of instinctive engineering.

Spider don’t simply make webs to hang around in, they can spin one around their own abdomen as a cocoon for their offspring or use light spider silk as a balloon to fly around with. Some spider are more active hunters and among those, some use webs as ‘nets’ like arachnid gladiators.

The webs, in their many forms, are not only marvels of engineering, but also of materials science. The spider silk of different species can differ in properties, but it can be up to three time tougher than Kevlar and five times stronger than steel. Add to that that it’s very flexible, water soluble, biocompatible, and biodegradable, and you’ve got a miracle material for things as diverse as armor, running shoes, and surgical thread.

In fact, a lot of people are trying to produce spider slik on an industrial scale through a variety of approaches.

But back to the engineering part. Why do spiders build their webs the way they do? A lot of spider webs — the hanging around kind — are asymmetrical. The hub of the web, the point where the threads converge, is generally higher up. And, sitting there, the spider almost always looks down. The possible reason? Gravity. It’s easier to run fast when you’re going down and gravity gives you a little extra ‘oomph’.

What would happen if we put web-building spiders in a low or zero gravity environment?

Space spiders

You got to love science, because a new study tried to figure it out for us.

Female golden silk-orb spider (Wikimedia commons, Charles J Sharp)

Two juvenile golden silk orb-weavers (Trichonephila clavipes) — well-known web-builders — hitched a ride to the International Space Station.

Once there, the spiders wanted to make it a bit more homely, regardless of gravity’s absence. Time to spin a web.

As expected, the webs of the young spiders were generally more symmetrical than their earthly creations. However, there was still quite a bit of variability in terms of space web symmetry.

When the scientists looked a bit closer at their eight-legged colleagues, they found that the webs they started building when the lights were on were asymmetrical, and the webs initiated in the dark were symmetrical. More specifically, webs built in illuminated conditions had their hub asymmetrically close to the light and the spiders themselves also faced away from the light source. In the dark, the spiders positioned themselves randomly in tems of gazing direction.

Turns out that spiders can use light as a back up engineering guide. (Back up, because on earth webs are asymmetrical even when constructed at night and spiders face down even in the dark.)

(An interesting aside, the female spider built a record-setting 34 webs.)

To conclude:

…in the absence of gravity, the direction of light can serve as an orientation guide for spiders during web building and when waiting for prey on the hub.

Spider webs. In space. Gotta love science.