蜘蛛如何飞翔

Spiders can crawl17. But some spiders can fly， too！ When spiders fly， it is called ballooning（飞航）. How do they do it？ Scientists showed that they use electricity18 in the air.

You do not feel it， but electricity is in the air all around you. Rub19 a balloon on your hair，and the hair will point20 towards the balloon. This is because of static electricity（静电）. Electricity can pull two things together. It can also push two things apart.

Before ballooning， spiders point their body up into the air. They send out a thin line of silk. The electricity in the air pulls on the silk. The electricity in the ground pushes the silk away. The spider lifts off into the sky！

蜘蛛能夠爬行，但有些蜘蛛还会飞！这种行为叫做“飞航”。它们是如何做到的？科学家们已证明，它们是从大气电场中获得了助力。

尽管无法察觉，我们四周的空气实际上充斥着电荷。就像你对着头发摩擦一个气球，发丝便会被气球吸引过去，这就是静电的效果。静电能够使物体相互吸引或排斥。

“飞航”前的蜘蛛会将身体扳直，对着天空吐出一根极细的蛛丝。大气中的正电荷会拉拽蛛丝，地表的负电荷会将蛛丝推开，如此一来，蜘蛛便可乘电飞行！

Did you know？

Spiders may balloon to find a new home or to get away from other animals.

蜘蛛小知识

飞航是个非常有效的远距离迁徙方式。这种本领不仅能帮助蜘蛛躲避捕食者和竞争对手的攻击，还能将它们带往资源丰富的新领地。