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Nhện "không cánh mà biết bay"
30 Aug, 2021
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spiders can fly, electrostatic (liên quan đến tĩnh điện) energy (năng lượng)!
Spiders have no wings, but they can take to the air nonetheless. They’ll climb to an exposed point, raise their abdomens (bụng dưới) to the sky, extrude (đẩy ra; chế tạo bằng cách đùn chất dẻo (nhựa, kim loại nóng chảy) qua miệng ống) strands (sợi tơ) of silk, and float away. This behavior is called ballooning. It might carry spiders away from predators (động vật ăn thịt, dã thú; người lợi dụng người khác (nhất là về (tài chính) và tình dục) and competitors (đối thủ), or toward new lands with abundant resources. But whatever the reason for it, it’s clearly an effective means of travel. Spiders have been found two-and-a-half miles up in the air, and 1,000 miles out to sea.
...spiders can sense the Earth’s electric field, and use it to launch themselves into the air.
Every day, around 40,000 thunderstorms (bão có sấm sét và thường mưa to) crackle (kêu răng rắc, kêu lốp bốp) around the world, collectively turning Earth’s atmosphere (khí quyển) into a giant electrical circuit (mạch điện khổng lồ). 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.
Tags: science
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