World Wide Web II

This is probably the first blog since we started in 2011 that has not featured a photo of a critter. But you can certainly see where they have been. If you have been cycling or walking recently you would have felt it. Or if you have been driving when the sun is just at the right (correct) angle you maybe would have seen it – silk streamers festooned on everything. Not just one or two but thousands, dare I say millions of them (pictured left). One of the sources of this phenomenon is spiders.  A previous blog (Keeping the wolves from your door) featured Wolf Spiders and mentioned that the young spiderlings disperse by releasing a strand of silk into the breeze and ‘ballooning’ away. Now is that time.

Recent studies have shown that simply releasing a silk strand into the breeze does not provide the required lift to float the spider away. Spiders use the earth’s electric field to get the required lift. When released the silk strand picks up a negative charge, the same as the surface on which the spider is sitting. This creates a repulsive force. In addition the air is positively charged. Spiders can detect these electric fields using sensitive hairs on their bodies and the electrical repulsive and attractive forces assist them to get airborne on their silk streamer. It is an effective way to disperse. Spiders have been found many kilometres in the air, and thousands of kilometres out to sea.

In these times of restricted air travel and climate change denial, the invertebrate world seems little fazed and is travelling using renewable energy.