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When we think of airborne organisms, spiders do not usually come to mind. However, these wingless creatures were found 4 km from the sky, scattering hundreds of kilometers. To disperse, they "swell", by which they rise to the top of a prominence, let out the silk and fly away. The wind was considered the trigger and the driving force behind this behavior, but a pair of biologists from the University of Bristol, UK, shows that spiders can swell without wind if a vertical electric field is present
Hot air balloon spider showing tiptoe position on a daisy. Photo credit: Michael Hutchinson.
"Many spiders swell with multiple strands of silk that fan out, suggesting that a repulsive electrostatic force is needed," said lead author Dr. Erica Morley, an expert in Sensory Biophysics at the School of Biological Sciences at the University of Bristol
"Current theories do not predict hot air balloon trends using only the wind as a motor. days there are big numbers that take on air, while on other days no spider will try to inflate at all? "
" We wanted to know if there was Meme it other external forces as well as aerodynamic drag could trigger the balloon and what sensory system they could use to detect this stimulus. "
The solution to the mystery could lie in the atmospheric potential gradient (APG), a circuit global electric that is always present in the atmosphere.
APGs and electric fields surrounding all matter can be detected by insects. For example, bumblebees can detect electric fields between themselves and flowers, and bees can use their charge to communicate with the hive.
Spider silk has long been known as an effective electrical insulator, but until now, it was not known. that spiders could detect and react to electric fields in the same way as bees.
In the new study, Dr. Morley and his colleague, Professor Daniel Robert of the School of Biological Sciences at the University of Bristol exposed Linyphiid spiders to laboratory – controlled electric fields that were quantitatively equivalent to those found in the atmosphere.
They noticed that the activation and deactivation of the electric field caused a rise or fall of the spider (off), proving that spiders can be airborne in the absence of wind when 39, they are subject to electric fields.
"Previously, wind or thermal dragging forces were thought to be responsible for this mode of dispersion, but we show that electric fields, at concentrations found in the atmosphere, can trigger the swelling and provide lift in the absence of air movement, "said Dr. Morley,
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"The next step will be to look to see if other animals detect and also use electric fields to inflate the balloons, "she added.
" We also hope to conduct further investigations on
The results appear this week in the journal Current Biology .
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Erica L. Morley and Daniel Robert: Electric Fields Raise Hot Air Balloons in Spiders Current Biology Published online 5th of July t 2018, doi: 10.1016 / j.2020.05.057
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