Spiders Can Fly. Here's How

Spiders can fly, without wings. It's called ballooning: a tiny spider climbs to a high point, tests the air, releases a fan of ultra-thin silk and floats away, sometimes kilometers up and hundreds of kilometers from where it started. In this video we explain how they take off, why the silk is so special, and the surprising discovery that the electric field in our atmosphere can lift a spider even when there is no wind at all. CHAPTERS 0:00 Spiders can fly 0:24 Darwin and the spiders that landed on the Beagle 1:40 How a spider takes off 2:18 The silk: up to 60 ultra-thin threads 3:13 Is it just the wind? 3:36 Electricity in the sky 4:23 The Bristol experiment 5:30 How spiders sense the field 6:18 Why fly at all? 7:11 Krakatoa and blankets of silk 7:56 So, how do spiders fly? THE SCIENCE IN BRIEF • In 1832, about 60 miles (≈100 km) off South America, Charles Darwin saw vast numbers of small spiders arrive on the Beagle on silk threads. • Ballooning spiders have been collected nearly 5 km above the ground and on ships more than 1,600 km from land. • Before take-off, spiders "tiptoe" (stand tall, abdomen up) and many raise a front leg to test the air. • Crab spiders released up to 60 silk fibers, about 3 m long and about 200 nm thick, and launched only in gentle wind under ~3 m/s (Cho et al., PLOS Biology 2018). • The atmosphere carries a natural electric field of about 100 V/m on a clear day. In a sealed box with no airflow, spiders ballooned when an electric field was switched on, and rose or dropped as it was switched on or off. Their sensory hairs (trichobothria) responded to the field (Morley & Robert, Current Biology 2018). • In nature, wind, rising air and electric fields probably work together. • Ballooning spreads spiderlings away from crowded hatching sites, and helps spiders reach new land such as Krakatoa after its 1883 eruption. SOURCES • Morley EL, Robert D (2018). Electric fields elicit ballooning in spiders. Current Biology 28:2324–2330. • Cho M, Neubauer P, Fahrenson C, Rechenberg I (2018). An observational study of ballooning in large spiders: nanoscale multifibers enable large spiders' soaring flight. PLOS Biology 16(6):e2004405. • Darwin C. Journal of Researches (The Voyage of the Beagle), 1839. • Glick PA (1939). The distribution of insects, spiders and mites in the air. USDA Technical Bulletin 673. #CreatureMechanics #spiders #ballooning #animalfacts #insects #science Footage: Pixabay. Music: Pixabay. Diagrams and animations: original.