Analysis of the microstructure of Xenodontinae snake scales associated with different habitat occupation strategies

Abstract

The morphology of many organisms seems to be related to the environment they live in. Nonetheless, many snakes are so similar in their morphological patterns that it becomes quite difficult to distinguish any adaptive divergence that may exist. Many authors suggest that the microornamentations on the scales of reptiles have important functional value. Here, we examined variations on the micromorphology of the exposed oberhautchen surface of dorsal, lateral, and ventral scales from the mid-body region of Xenodontinae snakes: Sibynomorphus mikani (terricolous), Imantodes cenchoa (arboreal), Helicops modestus (aquatic) and Atractus pantostictus (fossorial). They were metallized and analyzed through scanning electron microscopy. All species displayed similar microstructures, such as small pits and spinules, which are often directed to the scale caudal region. On the other hand, there were some singular differences in scale shape and in the microstructural pattern of each species. S. mikani and I. cenchoa have larger spinules arranged in a row which overlap the following layers on the scale surface. Species with large serrate borders are expected to have more frictional resistance from the caudal-cranial direction. This can favor life in environments which require more friction, facilitating locomotion. In H. modestus, the spinules are smaller and farther away from the posterior rows, which should help reduce water resistance during swimming. The shallower small pits found in this species can retain impermeable substances, as in aquatic Colubridae snakes. The spinules adhering to the caudal scales of A. pantostictus seem to form a more regular surface, which probably aid their fossorial locomotion, reducing scale-ground friction. Our data appear to support the importance of functional microstructure, contributing to the idea of snake species adaptation to their preferential microhabitats.Keywords: scales, microstructure, snakes, Xenodontinae, SEM. provavelmente auxilia na locomoção fossorial, reduzindo o atrito com o solo. Nossos dados parecem corroborar a importância da microestrutura funcional, contribuindo para a hipótese de adaptação das espécies de serpentes aos seus microhabitats preferenciais. Análise da microestrutura de escamas de serpentes Xenodontinae em associação à ocupação de diferentes microhabitatsPalavras-chave: escamas, microestrutura, serpentes, Xenodontinae, MEV.sisted of museum specimens from the Alphonse Richard Hoge collection at the Instituto Butantan (IB).In an attempt to avoid errors derived from phylogenetic factors, the species chosen all belong to the same subfamily (Xenodontinae).Dorsal, lateral and ventral scales were taken from the mid-region of the body of five adult individuals (males, 2 scales, and females, 3 scales) of each species. The scales were placed in numbered tubes and duly identified for each species. Distilled water and neutral soap were added to the tubes. Each tube was manually shaken for about 1 minute to remove any probable impurities. Scales were then removed...

Histology of the Skin of Three Limbless Squamates Dwelling in Mesic and Arid Environments

“…E,F and A). These microstructures differ from the pits and spinules reported in some xenodontine snakes (Rocha‐Barbosa and Moraes e Silva, ). The epidermis in C. cerastes is thicker than the epidermis of I. braminus and D. zarudnyi (Fig.…”

“…c erastes are tough, which is consistent with the morphology (keeling and micro‐ornamentation). These could be adaptations linked to the stress produced by desertic habitats (Rocha‐Barbosa and Moraes e Silva, ).…”

Microstructure of scales in selected lizard species

“…Scales protect the body of squamates, aid in distinction between families, allow moisture to be retained, aid in locomotion, occasionally aid in prey capture, and alter the surface characteristics, such as roughness to aid in camouflage (Abo-Eleneen and Allam, 2011). However, another study reported that scales do not only play an important role in distinguishing between families , but are important at the generic and species levels (Rocha-Barbosa and Moraes e Silva, 2009). Electron microscopy and ultrastructure studies of the squamate scale surfaces are very important for the analysis of scale microstructures.…”

Coupling effect of morphology and mechanical properties contributes to the tribological behaviors of snake scales

“…Friction remains a big concern in engineering and recently, more investigations have been made on the structures and materials of snake scales to achieve better understanding of the frictional behaviors (Abdel-Aal et al, 2012; Arzt et al, 2003; Benz et al, 2012; Berthé et al, 2009; Hazel et al, 1999; Klein et al, 2010; Klein and Gorb, 2012; Marvi and Hu, 2012; Rechenberg, 2003; Rocha-Barbosa and Moraes e Silva, 2009). In these reported cases, snake scales have manifested various desirable performance, such as adhesion reduction (Arzt et al, 2003), wear resistance (Rocha-Barbosa and Moraes e Silva, 2009) and frictional anisotropy (Benz et al, 2012). In particular, it has been suggested that distinct skin microstructures account for different frictional properties in discrete body positions (Berthé et al, 2009).…”

“…In particular, it has been suggested that distinct skin microstructures account for different frictional properties in discrete body positions (Berthé et al, 2009). It has also been shown that the functional microstructure on scales is an adaptation of snake species to their preferential habitats (Rocha-Barbosa and Moraes e Silva, 2009). Moreover, mechanical analysis of snake epidermis has revealed a gradient of hardness and elastic modulus, which corresponds to the respective inhabiting conditions, indicating that such a gradient is a potential adaptation to locomotion and wear reduction on substrates (Klein et al, 2010; Klein and Gorb, 2012).…”