Some spiders can catch onto breezes that send them flying across oceans and high up into the skies by ballooning—releasing “numerous strands of silk that they spin up to six feet long.”
And those threads of silk, from 100 to a few hundred nanometers wide (a human hair is 80,000 to 100,000 nanometers in diameter), are so thin and lightweight that they are suspended in the air like a thread, or a hair, in molasses.
Compared to a silk thread, the air is like a thick fluid, so the effect of gravity is easily counteracted by what you might call the stickiness of the air. In a breeze, the flowing air carries the silk threads along with it, as the spider rides beneath.
Aeronautical engineer Moonsung Cho has been studying the physics of spiders, specifically crab spiders, for five years. This ScienceTake video from The New York Times showcases a few excellent videos from his research in nature and in the lab.The incredibly strong (and massive) web of the Darwin’s bark spider, Spiders Tune Their Webs Like A Guitar, ‘flying’ spiders that can glide through the air from tree to tree, and To Demonstrate How Spiders Fly (1909).
Bonus vid: Look Up! The Billion-Bug Highway You Can’t See.