Evidence of a molecular boundary lubricant at snakeskin surfaces

Baio, Joe E.; Spinner, Marlene; Jaye, Cherno; Fischer, Daniel A.; Gorb, Stanislav N.; Weidner, Tobias

doi:10.1098/rsif.2015.0817

Cited by 27 publications

(23 citation statements)

References 57 publications

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“…These results suggest that the surface conditions did not change after CHCl 3 treatment. Based on this observation, we assumed that the surface of firebrat scales is not covered by waxy compound layers that greatly influence for the friction force measurements by changing surface morphologies and, thus, we measured the friction force directly (in this study, we did not consider the thin layer of epicuticular grease nor the possibility of the existence of a molecular boundary lubricant at the firebrat surfaces, such as in snake skin [31], because those are difficult to remove completely). Furthermore, if surface waxy compounds were completely removed, the surface conditions of wild-type firebrat would change failing to reproduce the actual friction properties of firebrat scales.…”

Section: Discussionmentioning

confidence: 99%

The Friction Properties of Firebrat Scales

et al. 2019

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Friction is an important subject for sustainability due to problems that are associated with energy loss. In recent years, micro- and nanostructured surfaces have attracted much attention to reduce friction; however, suitable structures are still under consideration. Many functional surfaces are present in nature, such as the friction reduction surfaces of snake skins. In this study, we focused on firebrats, Thermobia domestica, which temporary live in narrow spaces, such as piled papers, so their body surface (integument) is frequently in contact with surrounding substrates. We speculate that, in addition to optical, cleaning effects, protection against desiccation and enemies, their body surface may be also adapted to reduce friction. To investigate the functional effects of the firebrat scales, firebrat surfaces were observed using a field-emission scanning electron microscope (FE-SEM) and a colloidal probe atomic force microscope (AFM). Results of surface observations by FE-SEM revealed that adult firebrats are entirely covered with scales, whose surfaces have microgroove structures. Scale groove wavelengths around the firebrat’s head are almost uniform within a scale but they vary between scales. At the level of single scales, AFM friction force measurements revealed that the firebrat scale reduces friction by decreasing the contact area between scales and a colloidal probe. The heterogeneity of the scales’ groove wavelengths suggests that it is difficult to fix the whole body on critical rough surfaces and may result in a “fail-safe” mechanism.

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Section: Discussionmentioning

confidence: 99%

The Friction Properties of Firebrat Scales

et al. 2019

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“…Figure 3 shows IR spectra, FE-SEM images and photographs of water droplets on scales before and after washing by chloroform for 10 min. From these experiments, surface conditions were not changes, so firebrat scale surfaces are not covered by waxy compounds (In this study, we did not consider the possibility of a existence of molecular lubricant layer directly fixed on the body surface, such as a snake [26]). Friction forces on overlapped scales were measured using AFM with a needle-type probe and three kinds of scanning directions.…”

Section: Surface Chemical and Wettability Analysis Of Firebrat Scalesmentioning

confidence: 99%

The Friction Properties of Firebrat Scales

Hirai

Okuda

Saito

et al. 2018

Preprint

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Friction is an important subject for sustainability due to problems associated with energy loss. Recent years, surface micro- and nanostructures have attracted much attention to reduce friction; however, suitable structures are still under consideration. Many functional surfaces are present in nature, such as the friction reduction surfaces of snake skins. In this study, we focused on firebrats, Thermobia domestica, living in narrow spaces such as under bark, so their surface frequently contacts with surrounding surfaces. We speculate that their body surface would be adapted to reduce friction. To investigate the firebrat surface functions, firebrat surfaces were observed by using a field-emission scanning electron microscope (FE-SEM) and a colloidal probe atomic force microscope (AFM), respectively. Results of surface observations by the FE-SEM revealed that firebrats are entirely covered with scales, whose surfaces have micro groove structures. Scale groove periods around the firebrat's head are almost uniform within a scale but vary between scales. AFM friction force measurements revealed that firebrat scale reduces friction by decreasing contact area between scales and a colloidal probe. The heterogeneity of groove periods of the scales suggest that it is difficult to fix the whole body in particular rough surfaces and that lead to be "fail-safe".

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“…,b; Baio et al. ) and morphological studies (Russell, ; Schmidt & Gorb, ; Riedel et al. ) have contributed to our knowledge of functional morphology and diversity in squamate integuments, we still lack an understanding of how skin surfaces vary in three‐dimensions (3D) across an individual and how these surfaces change with body size.…”

Section: Introductionmentioning

confidence: 99%

“…toepads in geckos; Russell & Johnson, 2007;). While valuable biomechanical (Spinner et al 2013a,b;Baio et al 2015) and morphological studies (Russell, 2006;Schmidt & Gorb, 2012;Riedel et al 2015) have contributed to our knowledge of functional morphology and diversity in squamate integuments, we still lack an understanding of how skin surfaces vary in three-dimensions (3D) across an individual and how these surfaces change with body size. More importantly, we also lack the basic means of assessing the metrics of reptile skin in a high-throughput fashion for understanding how their form and function vary across a wide range of different squamate species.…”

Section: Introductionmentioning

confidence: 99%

Ontogenetic scaling patterns of lizard skin surface structure as revealed by gel‐based stereo‐profilometry

Baeckens

Wainwright

Weaver³

et al. 2019

Journal of Anatomy

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The skin surface structure of squamate reptiles varies greatly among species, likely because it plays a key role in a range of tasks, such as camouflage, locomotion, self‐cleaning, mitigation of water loss and protection from physical damage. Although we have foundational knowledge about squamate skin morphology, we still know remarkably little about how intraspecific variation in skin surface structure translates to functional variation. This gap in our understanding can be in part traced back to: (i) our lack of knowledge on how body size determines skin surface structure; and (ii) the lack of means to perform high‐throughput and detailed analysis of the three‐dimensional (3D) anatomy of reptilian skin surfaces in a non‐destructive manner. To fill this gap, we explored the possibilities of a new imaging technique, termed gel‐based stereo‐profilometry, to visualize and quantify the 3D topography of reptilian skin surface structure. Using this novel approach, we investigated intra‐specific and intra‐individual variation in the skin surface morphology of a focal lizard species, Anolis cristatellus. We assessed how various characteristics of surface topography (roughness, skew and kurtosis) and scale morphology (area, height, width and shape) scale with body size across different body regions. Based on an ontogenetic series of A. cristatellus males, we show that skin roughness increases with body size. Skin patches on the ventral body region of lizards were rougher than on the dorsum, but this was a consequence of ventral scales being larger than dorsal scales. Dorsal surface skew and kurtosis varied with body size, but surfaces on the ventral skin showed no such relationship. Scale size scaled isometrically with body size, and while ventral scales differed in shape from dorsal scales, scale shape did not change with ontogeny. Overall, this study demonstrates that gel‐based stereo‐profilometry is a promising method to rapidly assess the 3D surface structure of reptilian skin at the microscopic level. Additionally, our findings of the explanatory power of body size on skin surface diversity provide a foundation for future studies to disentangle the relationships among morphological, functional and ecological diversity in squamate reptile skin surfaces.

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Evidence of a molecular boundary lubricant at snakeskin surfaces

Cited by 27 publications

References 57 publications

The Friction Properties of Firebrat Scales

The Friction Properties of Firebrat Scales

The Friction Properties of Firebrat Scales

Ontogenetic scaling patterns of lizard skin surface structure as revealed by gel‐based stereo‐profilometry

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