What is it for? Researchers from the Poly-PEDAL Lab at the University of California, Berkeley, have been investigating.
“We show that a gecko’s tail functions as an emergency fifth leg to prevent falling during rapid climbing.”
explain authors Jusufi, A., D. I. Goldman, S. Revzen, and R. J. Full in their 2008 paper Active tails enhance arboreal acrobatics in geckos (published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) vol. 105, #11, pp. 4215-4219).
Discoveries were made by observing the behaviour of geckos which had been encouraged to ‘hover’ in a wind-tunnel. And slow-motion analysis of the resulting video footage (available here in .mov format) showed that –
“Should a gecko fall with its back to the ground, a swing of its tail induces the most rapid, zero-angular momentum air-righting response yet measured. Once righted to a sprawled gliding posture, circular tail movements control yaw and pitch as the gecko descends. Our results suggest that large, active tails can function as effective control appendages.”
“This work was supported by Defense Advanced Research Projects Agency/Space and Naval Warfare Systems Command Grant N66001-03-C-8045 (to R.J.F.), National Science Foundation Grant EF 0425878 FIBR (to R.J.F.), the Kurt and Barbara Gilgen Fund (A.J.), and the Burroughs Wellcome Fund (D.I.G.).”
Also see: Improbable Research Foldable (origami) gecko and fly and Severed Gecko’s Tail Poetry.