Tests on Locomotion of the Elongate and Limbless Lizard Anguis fragilis (Squamata: Anguidae)

Abstract

Anguis fragilis were filmed while traversing plane surfaces, fields of nails and pins at different spacings, and channels of different diameter. Lizards can move slowly on rough surfaces by lateral undulation, but with increased speed (and on smoother surfaces) they shift to slide-pushing accomplished by wide swings of the tail. The lizards undulate through fields of pins, often pushing at a few bends and pulling and pushing the trunk among these. In channels, they utilize continuous bend concertina, forming the initial bend anteriorly and adding posterior ones, either to the level of the cloaca or also onto the tail. Specimens respond to very tight pin arrangements (but not tight channels) as hiding sites, wedging themselves in place. The cloacal region often forms a site of discontinuity, with curves changing here; however, the trunk and tail seem to have equal capacity for bend formation without obvious deficits in autotomized specimens. Velocities of adults were relatively low, 1 cm/sec for slide-pushing, 4 cm/sec for lateral undulation, and 1 cm/sec for concertina.