The cantilever abilities of snakes

We quantified the abilities of snakes to extend the anterior body horizontally without support, and we evaluated data for 31 species representing five families. Generally, terrestrial snakes exhibit rather uniform cantilever ability and can extend the body 30-50% of total body length. Arboreal species exhibit statistically superior performance both within and among families, with some species extending the body to more than 50% of body length. Extreme divergence of cantilever abilities occurs between arboreal and aquatic species. Intraspecific comparisons also show that juvenile snakes cantilever better than adults, presumably due to a lower mass relative to body length. Musculoskeletal features of the vertebral column are generally conserved in evolutionary terms, thus possibly explaining the generally uniform cantilever abilities in large numbers of snake species. However, several modifications of vertebrae and associated epaxial muscles and their tendons appear to be related to cantilever performance.