Orb spider

The golden orb spider. The smaller spider is the male. Image taken in Manzanillo, Costa Rica.

This majestic creature is a golden orb spider, so called not because of its golden yellow and black appearance, but because sometimes, not always but sometimes, they make a web that is a lustrous gold color. We don’t know why, although one hypothesis is that the golden web might hold up better against sunlight. In the picture above, the large spider is the female, while the smaller one is the male. The females of these species are known cannibals, so he had better be careful. One study reported that at least some of the time, larger males were more likely to be eaten than smaller ones, suggesting a reason for why the males are so small compared to the females.

The reason why I chose to highlight this spectacular spider is because of the amazing material she produces to build her web and to catch prey-her silk. Of course, other spiders and invertebrates can also produce silk, but the silk from golden orb and black widow spiders is special (we’ll talk about black widows in another post). As far as we know, their silk is the strongest material, natural or man-made, in the world when comparing strength using the same weight of each material. Their silk is roughly 5 times stronger than steel and 3 times stronger than Kevlar. (An individual spider can make up to 7 different types of silk. The strongest is the drag line silk, which is the silk that makes the frame and spokes of their web.)

It has been calculated that a single strand of their silk that is the thickness of a pencil can stop a 747 in flight and that a 2cm strand should be strong enough to repeatedly lift 2 metric tons.

As you can imagine, this stuff has had scientists drooling for decades now and producing a synthetic spider silk has become the holy grail of material science. Using real spider silk has proved difficult because, as I’ve mentioned before, the spiders tend to eat each other. There has only been one large golden cloth made from real spider silk, and it took over 1 million spiders and several years to produce. It is displayed at the American Museum of Natural History in New York.

Some of the possible uses for a good synthetic spider silk include earthquake resistant bridges, sutures and bullet proof vests. But my absolute favorite possible use for spider silk was recently published by the Journal of Experimental Biology and it involves a different property of spider silk other than its strength. Spider silk contracts when it’s wet and expands when it’s dry. If you took a piece of drag line silk and wrapped it around your finger and then placed your finger under water, the silk would contract so much that it would cut off the blood supply to your finger. This important feature is probably what holds a web in place when it rains and adds extra weight to the web. Given that this material expands and contracts, one potential use is to make a humidity powered biomimetic muscle. That’s right, an artificial muscle that has the potential to be 50 times stronger than human muscle and is powered by water. Some of the suggested uses for this muscle include making compact actuators for robots, sensors and green energy production.

And what does the spider use her web for?

Golden orb spider

A golden orb spider descending on her prey. Image taken in Manzanillo, Costa Rica.

More specifically?

Special thanks to my husband Trey Jackson for filming, editing and donating this incredibly cool video.

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