The spiders did not release their silk balloons at random, the team found.
Instead, they raised one or two hairy legs aloft, apparently testing the wind
for 5 to 8 seconds. On cold and windy days, the spiders huddled on the side of
the platform and most did not launch. But if conditions were right — a warm,
gentle breeze no stronger than 3 meters per second — the spiders raised their
abdomens and released up to 60 silk threads, forming a triangular sheet that
bore them skyward, the researchers report on the online preprint server bioRxiv.
The study is the first to show that spiders, like any good aviator, carefully
evaluate wind conditions before takeoff.
