Daphné VAN RIET
After having been bitten by a radioactive spider, Spider-Man got superpowers! He can weave webs, climb on walls, swing from one building to another, and stop villains by trapping them in his web. In the film Spider-Man 2, Peter Parker stops a train full of passengers with his web. If it was not a film, do you think spider webs would have been strong enough to stop a train? Scientists prove that it is indeed possible.
Spiders Weaving Their Webs
Spiders are not insects; they are arachnids. That is why they have eight legs and a body made of two sections. They can produce silk, different types of silk even, with multiples functions: weave a web (beware that not all spiders can weave webs), protect them from predators, catch prey, and build cocoons, in which they can build a nest to lay their eggs.
Small appendage of the spider used to weave its web
One thread of silk is made of a protein chain. Inside the filament, there are two types of proteins. Some proteins, in crystalline form like sugar, guarantee the solidity of the thread. Others are amorphous and guarantee their elasticity.
Spiders produce proteins in glands found on the bottom of their tummy. Then, the proteins are stored in a liquid before being used. When the spider needs it, it will move the liquid out of its spinnerets. Spinnerets are a kind of stem that lies on the lower part of a spider’s abdomen. They are organs producing silk. Upon contact with the air, the mixture will turn into a silk thread through a chemical reaction.
The Spider Web strength
In the film, Spider-Man uses his web to stop a moving train, but is it possible? Well, you might be surprised that the answer to that question is yes. The silk produced by spiders has two great advantages: it has great elasticity, and it can absorb a large amount of energy. It means it can absorb a big shock without even breaking. You could compare it to steel because the breaking strength of some threads is at least 1,75 gigapascals or 178 kg. per square millimeters. The edge of silk is that it is less dense than steel…
One single thread of silk is so strong that if it is 40 mm long and if it has a diameter of 5 micrometers (which is three times smaller than a human hair), it will be able to lift at least 100 mg. Said like that, it might not seem that impressive. However, when you think bigger, a thread having a diameter of 1 mm could lift 5 kg, and a thread with a diameter of 2 cm could lift 2 tonnes.
Spider Webs, the new super gadget for Humans?
The silk thread of a spider is particularly strong, but can it stop a train? A group of students from the University of Leicester calculated that to stop the same train as in Spider-Man 2 (with 4 wagons full of passengers), you would need a resistance of approximately 30,000 newtons. Besides, the material to stop the train must have a breaking strength of 3,12 gigapascals. That means that under that massive force of the moving train, the thread will not break.
Some spiders have the ability to produce threads whose breaking strength can get to 12 gigapascals. It is the case for the species Caerostris darwini. Thus, in the real world, Spider-Man would have been able to stop the train.
Is the strength of a spider thread great enough to stop a plane? If the thread is as thick as a pencil, it could even stop a flying Boeing 747! That is what professor Xiang Wu from the National University of Singapore says.
And What About Swing from One Building to Another?
Could we swing at the end of a silk thread like Peter Parker? Yes and no. Researchers from the University of Oxford used the silk of spiders coming from Australia to try to lift a human being. The chosen spiders produce a very resistant thread. However, one thread was not strong enough, but if you make a rope with 26,349 filaments, you could lift up to 100 kg!
Before using spider webs as your next means of getting around, more researches need to be done.
One Day Spider Webs Will Be Inside Us
Scientists are leading research to be able to use spider silk inside the human body. That silk could be used to repair ligaments, tendons, or damaged bones. The proteins you can find inside spider silks have the shape of a long filament. It is also the case for proteins inside our tendons and muscle fibers. Since spider silk is more solid than our ligaments and biocompatible with our body, our immune system will not reject it, or not much, if it is put inside our body. Using it to repair some parts of our body would be a great idea!