RIVERA, G.*; SAVITZKY, A. H.; HINKLEY, J. A.; Old Dominion University, Norfolk, VA; Old Dominion University, Norfolk, VA; NASA Langley Research Center, Hampton, VA: Mechanical properties of the integument of the Common Garter Snake, Thamnophis sirtalis (Serpentes: Colubridae)

The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies have concentrated on modifications of the skull and cephalic musculature associated with macrophagy. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. We examined mechanical properties of skin along the body axis in male Thamnophis sirtalis (Colubridae). From each of 14 specimens we excised nine circumferential strips of skin, each spanning 10 ventral scales, spaced at increments of 10% of the ventral scale count. Each circumferential strip was divided into two samples. One sample was subjected to a uniaxial tensile test along the transverse axis, to determine circumferential compliance; the other sample was fixed for histological examination. Tensile tests were conducted on 126 skin samples, and the mechanical properties were analyzed using a randomized-block MANOVA. Significant differences in those properties exist among regions of the body. In general, prepyloric skin was found to be more compliant than postpyloric skin, consistent with the demands of macrophagy.