This week I’ll explore some topics outside of politics. It will improve my sanity, and, judging by the volume of emails received last week, also that of my readers.
I’ll start with flying spiders. Now that should put your mind at rest…. https://www.theguardian.com/world/2019/jan/11/raining-spiders-brazil
If you look at the link attached above, you’ll see a video of a sky that seems to have spider raindrops or snowflakes, 1000s of them, come down. It is a phenomenon associated with particularly hot air. (Climate change? Nope, not going there today.) Before you cringe in disgust, listen to the really amazing facts associated with these spiders.
First of all, they are tremendously good for the environment, because they devour insects and pests. (Which reminds me, so are ducks. They are increasingly used to replaced toxic pesticides in rice farming – check it out here: https://www.bbc.com/news/av/world-europe-43588774/dumping-pesticides-using-ducks-instead)
Secondly, they are amazingly social – out of 40.000 species of spiders there are only 23 that form communities, and parawixia bistriata is one of them. They basically curl up in a tight ball in the trees during the day
and then come out at dusk to weave giant, connected, invisible nets where they hang out waiting for dinner. A colony can have up to 50.000 individuals with females outnumbering males at a high ratio. If there is enough wind, the nets break loose and get carried, spiders and all, across the sky which makes for the illusion of raining spiders.
And before you comfort yourself with the thought that all of this happens between Panama and Argentina, I have news: ballooning spiders have arrived in Texas. (Maybe they could stand in for the wall, building an elongated web along the border? I forgot, no politics. My bad.)
The good news: they are not poisonous, and they are exceedingly small (otherwise they’d be too heavy to float in the air) so that their bite, if it ever happens, is no more harmful than a mosquito’s.
The fascinating news: individual spiders do not only travel with the wind, but use flight by electrostatic compulsion, reaching heights of over a mile and many more in distance.
Every day, around 40,000 thunderstorms crackle around the world, collectively turning Earth’s atmosphere into a giant electrical circuit. The upper reaches of the atmosphere have a positive charge, and the planet’s surface has a negative one. Even on sunny days with cloudless skies, the air carries a voltage of around 100 volts for every meter above the ground. In foggy or stormy conditions, that gradient might increase to tens of thousands of volts per meter. Ballooning spiders operate within this planetary electric field. When their silk leaves their bodies, it typically picks up a negative charge. This repels the similar negative charges on the surfaces on which the spiders sit, creating enough force to lift them into the air. And spiders can increase those forces by climbing onto twigs, leaves, or blades of grass. Plants, being earthed, have the same negative charge as the ground that they grow upon, but they protrude into the positively charged air. This creates substantial electric fields between the air around them and the tips of their leaves and branches—and the spiders ballooning from those tips.
The whole argument can be found here:
https://www.theatlantic.com/science/archive/2018/07/the-electric-flight-of-spiders/564437/
Nature will never cease to amaze me. And here is a little something to commemorate the spiders’ victims:
Photographs are of spiderwebs found in the Northwest woods.
Sara Lee
Pretty amazing post!
The science I couldn’t really grasp, but the idea of a Wall of those spiders? Genius!