The thought of crawling spiders can give many people the heebee-jeebies. Now, what if I told you that spiders can fly too!
In fact, it was naturalist Charles Darwin who first encountered these flying spiders on his voyage across South America on the HMS Beagle. He noticed that gossamer spiders were landing on his ship and magically soaring up into the air, even in calm weather.
Ever since, scientists have been trying to figure out the science behind this fascinating phenomenon.
A Little About Spiders
Spiders are a species of arthropods called arachnids. There are over 45,700 spider species (as of November 2015) and are found all over the world except for Antarctica. They range in size from the smallest patu digua which is about the size of a pin-head, to the Goliath bird-eater tarantula.
Spiders are easily identified by their characteristic eight legs. They also have chelicerae (their mouthparts) with fangs attached to them. Many spiders are harmless, but when certain spiders inject their venom into you, it is poisonous.
They capture food by spinning an intricate web using their own sill which is excreted through their spinnerets. Once an unsuspecting creature flies into the web, the spider pounces on it and kills it by dissolving its organs. If the spider is full, it will wrap up the creature in silk and save it for later. Did you know that spider silk is stronger than steel?
The Art of Spider Ballooning
The phenomenon by which spiders take flight is known as ballooning. It was thought that spiders might be using the wind to launch themselves into the air. But we now know it has to do with electricity.
You see our Earth’s atmosphere has a positive charge which interacts with the ground’s negative charge to create an electric potential (just like the two terminals of a battery). On calm days, this potential can be 100 volts/meter, and is much higher on stormy days. Spiders have tiny hairs on their exoskeletons that can detect this electric charge, and use it to create lift.
To prove this, scientists used sealed tanks with electromagnetic fields in them. They then placed baby spiders inside the tank, and noted that the spiders were able to balloon easily when the electromagnetic fields were stronger.
How do spiders achieve this remarkable feat? They test the air with one of their eight legs. The ideal condition for flying is a light wind and a little humidity. As they start to lift off, they tiptoe ever so slightly while lifting their abdomens. Throughout the process, the spiders will produce silk that can reach an impressive six feet in length! As the silk picks up a negative charge, they lift off. They can coast up to three miles on land, and a thousand miles over the ocean. They can even fly as high as planes in the upper atmosphere!
Spiders are indeed exceptional creatures with extraordinary abilities. Would you like to see a flying spider?
Sources: Fortune, PBS, The Atlantic, Wikipedia, NYTimes, Cosmos Magazine