Researchers discover that spiders rely on the electric field in the Earth’s atmosphere to provide lift. (Image Credit: Vidar Nordli-Mathisen/Unsplash)
While completely wingless, some spider species evolved to take flight using nothing but their silk threads. Previous studies suggested that spiders accomplished this by using those threads to catch warming air updrafts, allowing them to sail on the wind. The latest study by Notre Dame University-Louaize and University of California researchers propose that spiders may tap into the atmosphere’s electric field for lift.
In 2018, a University of Bristol study revealed that electric fields generated by the weather apply sufficient force on oppositely-charged spider silk. This would then cause the thread and spider to lift into the air. Scientists used special simulators designed for Hollywood films to determine how the silken thread interacted with a charged field.
“The ballooning of spiders is hypothesized to be caused by the presence of the negative electric charge of the spider silk threads and the positive electric potential field in the Earth’s atmosphere,” the research explains.
Measuring the tiny spider strand silk charges has proven difficult, hindering efforts to prove the theory of spiders using electricity to fly. Now, the researchers involved in the latest study used special software, which is commonly utilized for hair tracing purposes, to model spider silk and electricity in the Earth’s atmosphere.
The algorithm allowed the team to separate a strand of spider silk into many pieces, which bend and stretch. This is advantageous because spiders typically rely on more than one strand to lift off the ground. Also, researchers can produce models of the electrically charged strands as they apply forces on the others.
The team added simulation parameters, which include the gravity effects, electric field reduction from height, the separate electric charge from each thread, and the air resistance effect on the threads. Afterward, they attached between two and eight virtual hairs to a 2mm-wide sphere, serving as a tiny spider. While running the simulations, they discovered that negative charges along the threads pushed apart, causing the thread strands to form an inverted cone shape. In effect, this decelerated their descent, making them fall.
As a result, gravity, drag, electrostatic lift, and thread separation contributed to the spiders’ flight capability without relying on air currents.
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