Biomechanical Analysis of Jumping in Anolis carolinensis (Reptilia: Iguanidae)

Abstract

Based on high speed films (200 frames/sec), the horizontal jump of adult male lizards, Anolis carolinensis is kinematically analyzed. The jump consists of four successive stages: hind limb posturing, takeoff, flight, and landing. Compared to aspects of jumping previously described for vertebrates, A. carolinensis has one unique quality: the hind limb posturing phase which occurs prior to the takeoff and involves a forward extension of the hind limbs and thus a bending effect onto the vertebral column. Takeoff is highly stereotyped and landing extremely variable. During the flight, the angle of the lizard with the horizontal is about 30* and does not change greatly. A peak acceleration of about 25 m/sec/sec occurs during the takeoff phase, and the mean takeoff angle is 31.5* plus/minus 5.8* for a jumping distance of 10 to 20 cm (n = 44 jumps). The mean maximum of vertical force exerted by each foot is 0.041 ? 0.011 N for lizards of mass 3.7 ? 0.9 g. At the point of maximum acceleration, the hind limbs extend considerably, the tibia and fibula are nearly vertical, and the femur is horizontal. The forelimb extends prior to maximal acceleration and is predicted to avoid a forward pitching. Successive storage and recovery of kinetic energy through bending of the vertebral column and the elastic structures of the hind limb are discussed. Em