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Knowledge
Friday, July 6, 2018 [19659005] They do not have wings, but fly from any way: Some spiders can be carried by ropes that hang long distances in the air. Wind is probably not the only means of transport.
Some spiders can perceive electric fields in the air and can be transported with their help. They smell electricity with tiny hair on their bodies, report researchers at Bristol University in the journal "Current Biology". "We do not know if electric fields are needed to allow the" airship "of spiders," explains Erica Morley. "But we know that they are enough."
The phenomenon of flying spiders has been known for a long time. The animals climb on a hill, around a flower, stand on tiptoe and stretch their abdomen in the air. Then they form several silk threads that attract them, and are finally raised by swinging them in the air. In this way, you can overcome hundreds of kilometers.
During the Indian summer, canopy spider webs (Linyphiidae) often attract attention, as they usually turn on grbadlands near the ground. The threads on which they sail in the air are, according to one explanation, reminiscent of the hair of old women – hence probably the name of Indian summer.
First Theory In The 19th Century
Already in the early 19th century the early theories had to come. While spiders fly, British scientists write in their newspaper article. They suspected that animals were using wind or electrostatic forces.
Charles Darwin also pondered the phenomenon when hundreds of small spiders landed aboard the "Beagle" expedition ship and then took off at high speed – although no wind was blowing. blown at all. Darwin has described some of the unresolved questions about wind theory: Spiders fly in the air only at very low wind speeds – but how do they handle this at high speeds? And also animals that, according to the calculations of the model, are really too heavy for that? Why do some days big numbers go up in the air, while on other days no spiders get up?
To clarify these questions, Morley and his colleague Daniel Robert have now badumed that electric forces were the source of spiders make flight possible. The context is the fact that there is an electric field between the earth and the upper atmosphere, whose strength and polarity fluctuate depending on the weather conditions. It is well known that bumble bees and bees use the electric field to feed and communicate
Artificial electric field in the laboratory
The researchers created an artificial electric field in the laboratory that they could light and switch off. They made sure that there was no air movement in their pilot plant. Then they put canopy spiders on a launch pad. When the researchers turned on the electric field, they picked up most of the spiders. Once in the air, the researchers were able to raise and lower the spiders by activating or deactivating the electric field.
Other experiments have shown that small sensory hairs on the body of spiders – called Trichobothria – react and react. depending on the strength of the electrical stimulus. Spiders feel the electric charge, the researchers conclude. They suspect that air movements and electrostatic forces jointly raise spiders in the air.
Scientists now want to study the phenomenon further. Other animals such as caterpillars or spider mites are spread in the air. We do not know if they also use electric fields to do it.
Understanding the mechanisms that underlie the release of animals is essential to understanding gene flow and population dynamics, for example, the researchers write. Spiders consume 400 to 800 million tonnes of biombad per year worldwide and thus significantly influence the composition and diversity of ecosystems.
Source: n-tv.de
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