74.4 Saturday, Jan. 5 Gliding Geckos Perch on a Tree Trunk Assisted by Active Tails JUSUFI, A.*; BYRNES, G.T.; FULL, R.J.; Univ. of California, Berkeley email@example.com
Laboratory studies of air-righting and equilibrium gliding revealed that geckos could use tail movements for maneuvering (Jusufi et al. 2008, 2010). We measured geckos, H. platyurus, in a Southeast Asian rainforest to study tail function during aerial descent and gliding in nature. Field video revealed that geckos traveled horizontal distances from tree to tree of up to 4m with gliding speeds ranging from 5.4 to 7.5m/s and angles of attack of approximately -15° to -20° at mid-glide. Preparing to land, geckos pitched their body up to 32° to 35° and decelerated to speeds ranging from 4.4 to 6.3m/s. Gliding geckos initiated their perching maneuver with a 15° angle of attack relative to horizontal. Near head-on collisions with the tree trunk pitched the torso vertically as high landing forces were absorbed by the body and tail. After vertical alignment with the tree trunk, the anterior section of the body pitched up to 100° away from the trunk, anchored by only the hind limbs and tail. Tail forces allowed recovery from the extreme pitch back angles by reducing stress on the rear legs. Of the gliding geckos that reached the tree target (n=7), the majority (86% of trials) alighted safely on the vertical target. By contrast, tailless geckos experienced catastrophic falls in 75% of trials after crashing into the tree (n=4). Results reveal geckos use tails as shock-absorbers and stabilizers to reduce and control high impact forces acting on the limbs allowing effective landing at high speeds. Gecko’s perching behavior could be initiated by the same reflex discovered during climbing where forefoot slippage stimulates tail depression. Strategies incorporating tail assisted responses can improve the vertical landing performance and stability of both animals and robot planes.