Functional Morphology and Biomechanics, Zoological Institute of the University of Kiel, Am Botanischen Garten 1-9, 24098 Kiel, Germany.
J R Soc Interface. 2012 Nov 7;9(76):3140-55. doi: 10.1098/rsif.2012.0479. Epub 2012 Aug 15.
On the basis of structural and experimental data, it was previously demonstrated that the snake integument consists of a hard, robust, inflexible outer surface (Oberhäutchen and β-layer) and softer, flexible inner layers (α-layers). It is not clear whether this phenomenon is a general adaptation of snakes to limbless locomotion or only to specific conditions, such as habitat and locomotion. The aim of the present study was to compare the structure and material properties of the outer scale layers (OSLs) and inner scale layers (ISLs) of the exuvium epidermis in four snake species specialized to live in different habitats: Lampropeltis getula californiae (terrestrial), Epicrates cenchria cenchria (generalist), Morelia viridis (arboreal) and Gongylophis colubrinus (sand-burrowing). Scanning electron microscopy (SEM) of skin cross sections revealed a strong variation in the epidermis structure between species. The nanoindentation experiments clearly demonstrated a gradient of material properties along the epidermis in the integument of all the species studied. The presence of such a gradient is a possible adaptation to locomotion and wear minimization on natural substrates. In general, the difference in both the effective elastic modulus and hardness of the OSL and ISL between species was not large compared with the difference in epidermis thickness and architecture.
基于结构和实验数据，先前已经证明蛇的表皮由坚硬、坚固、不灵活的外表面（Oberhäutchen 和 β 层）和较软、灵活的内层（α 层）组成。目前尚不清楚这种现象是蛇适应无肢运动的一般现象，还是仅适应特定条件，如栖息地和运动方式。本研究的目的是比较四种生活在不同栖息地的蛇种的蜕皮表皮的外层鳞片层（OSL）和内层鳞片层（ISL）的结构和材料特性：Lampropeltis getula californiae（陆生）、Epicrates cenchria cenchria（多用途）、Morelia viridis（树栖）和 Gongylophis colubrinus（沙埋）。皮肤横截面的扫描电子显微镜（SEM）显示，不同物种的表皮结构存在很大差异。纳米压痕实验清楚地表明，在所研究的所有物种的表皮中，材料特性沿着表皮呈现梯度变化。这种梯度的存在可能是对在自然基质上运动和磨损最小化的一种适应。总的来说，与表皮厚度和结构的差异相比，物种之间 OSL 和 ISL 的有效弹性模量和硬度差异不大。
