On a calm day, a tiny spider climbs to a high point, raises its abdomen toward the sky and releases several silk threads. Moments later, it is no longer on the ground. How can it be carried away like this?
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This behaviour is called ballooning. The spider releases threads that lift and carry it, sometimes very high: one spider was found 4.5 km above ground. It does not fly like a bird; it is carried along passively.
Researchers at the University of Bristol tested an unexpected idea in tiny Erigone spiders. In the laboratory, they respond to an electric field even without wind, and try to balloon. When the field is switched on, the behaviour increases clearly; when it is switched off, spiders already in the air come back down.
Is electricity really carrying them in nature? That remains a hypothesis, since no field evidence has yet been published.
