Meeting Abstract

S11.3  Friday, Jan. 7  Aerial Righting Responses: A Comparative Approach JUSUFI, A.*; ZENG, Y.; FULL, R.J.; DUDLEY, R.; Univ. of California, Berkeley ardianj@berkeley.edu

Animals that fall upside down typically engage in an aerial righting response so as to reorient rightside up. This behavior can be preparatory to gliding or other aerial behaviors, and is ultimately necessary for a successful landing on extended legs. Air-righting reactions have been described historically in mammals, such as cats, rabbits, guinea pigs, rats and primates. The air-righting response of cats generally involves twisting and bending between the front and rear segments of the torso, thereby altering the instantaneous moment of inertia. Tail movements appear less important and the effect of leg motion is unknown. Here, we show aerial righting in both lizards and stick insects and illustrate the size dependence of this phenomenon and its relevance to subsequent aerial performance in parachuting and gliding animals. Geckos can use rotations of their large tails to reorient their bodies via conservation of angular momentum. Lizards with tails well exceeding snout-vent length are more effective at inducing reorientation in mid-air by redistribution of mass. Experiments in larval stick insects suggest that aerodynamic torques acting on bodies in a controlled posture may play the dominant role in the righting process of small invertebrates. Results suggest inertial and aerodynamic effects can play a role in the control of aerial righting. We suggest that the aerial righting response may be widespread among terrestrial arthropods and vertebrates and represents an important adaptation in the evolutionary acquisition of controlled aerial behavior.