Snake Scale Microstructure:
This study investigates whether micromorphological features of the oberhautchen of snake scales show adaptations to the animals' life habit. For the first time, the ventral scale microstructure of 41 snakes belonging to three different families (Pythonidae, Boidae, and Elapidae) is described. Species adapted to four different life habits (terrestrial, fossorial, arboreal, aquatic) were examined using scanning electron microscopy. Snakes (Serpentes) occur almost world-wide and occupy a variety of terrestrial, fossorial, arboreal, and aquatic habitats. Macromorphological adaptations to different life habits, such as body shape and size, are well known from the literature. Previous studies on snake scale microstructure were focused on dorsal scale microstructure. However, in spite of macroscopic similarity of the ventral scale surface among snakes, the ventral surface is extremely important from the functional point of view. Due to the loss of extremities, the epidermis of the ventral scale of a snake is in continuous contact with the substrate. Therefore, there is a special interest in revealing whether certain characteristics of ventral microstructure are determined by the biology of the species or if they reflect phylogenetic relationships. Careful analysis according to the author's newly revised terminology of microstructural features reveals that at least two major patterns of microstructure have evolved within snakes. The first comprises the ancestral microstructural pattern found in most of the snake families examined. The second pattern is derived and has evolved at least twice, independently. These two distinct types are assumed to represent different structural solutions for the same functional demands, such as propulsion generation due to frictional anisotropy, and minimization of wear. Modifications of certain features of these two major patterns appear to correlate with different strategies of habitat occupation. This study is of great interest to biologists studying animal integument, functional morphology, ecomorphology, and evolution of reptiles. In addition, the described diversity of microstructures might inspire surface scientists to mimic similar features in polymer surfaces, in order to generate innovative biologically- inspired surface-active materials with novel properties.