[ad_1]
But Erica Morley and Daniel Robert have an explanation. The duo, who work at the University of Bristol, has shown that spiders can feel the electric field of the Earth and use it to get into the air.
Every day, about 40,000 thunderstorms rustle around the world, turning the earth's atmosphere into a giant electric circuit. The upper parts of the atmosphere have a positive charge and the surface of the planet is negative. Even on a sunny day with a cloudless sky, the air carries a voltage of about 100 volts per meter above the ground. In foggy or stormy conditions, this gradient could increase to tens of thousands of volts per meter
Hot air balloon spiders operate in this planetary electric field. When their silk leaves their body, it usually takes a negative charge. This repels similar negative charges on the surfaces on which the spiders rest, creating enough strength to lift them into the air. And spiders can increase these forces by climbing on twigs, leaves, or blades of grass. The plants, being grounded, have the same negative charge as the land on which they grow, 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 flying away from these spikes.
This idea of electrostatic repulsion leakage was first proposed in the early 1800s. Darwin's Journey. Peter Gorham, a physicist, resurrected the idea in 2013, and showed that it was mathematically plausible. And now, Morley and Robert have tested it with real spiders.
First, they showed that spiders can detect electric fields. They put the arachnids on vertical strips of cardboard in the center of a plastic box and then generated electric fields between the ground and the ceiling of forces similar to what the spiders would live on the outside. These fields ruffled tiny sensory hairs on the feet of spiders, known as trichobothria. "It's like when you rub a balloon and hold it to your hair," says Morley.
In response, the spiders performed a set of movements called tiptoeing-they stood on the ends of their legs and glued their abdomens in the air. "This behavior is only seen before getting into a balloon," says Morley. Many spiders have actually managed to take off, although they are in closed boxes with no air circulation. And when Morley turned off the electric fields inside the boxes, the rising spiders fell.
It is especially important, says Angela Chuang, of the University of Tennessee, to know that spiders can physically detect electrostatic changes in their environment. "[That’s] the basis for a lot of interesting research questions," she says. "How do the different forces of the electric field affect the physics of take-off, flight and landing?" Do spiders use weather information to make decisions about when to break their webs? To create new ones? "
Source link
