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Warm-up process of the exuvia of B. rhinoceros. (a) Exuvia of B. rhinoceros, West African Gaboon viper. (b) IR-emission image of the exuvia of B. rhinoceros before illumination under ambient room conditions temperature, (c) after 1 min illumination, and (d) after 2 min illumination.
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The West African Gaboon viper (Bitis rhinoceros) is a master of camouflage due to its colouration pattern. Its skin is geometrically patterned and features black spots that purport an exceptional spatial depth due to their velvety surface texture. Our study shades light on micromorphology, optical characteristics and principles behind such a velvet...
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... scales transmitted less radiation, particularly in the wavelength range of 400-900 nm (Fig. 6b). Black and pale scales of B. rhinoceros had also different absorption char- acteristics. After one minute long warming up by electrical lamp illumination (near UV -visible light), dark areas of the exuvia were on average 2uC warmer than pale areas (Fig. ...
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... It is interesting to note that, although the statement that the roughness or attachment devices of animals exhibit a multilevel hierarchical structure is currently widely accepted, and it is attributed to the findings by S. Gorb (Kiel University) and his colleagues [24], along with other experts in the biology of animals [25], the Archard concept of a hierarchical multilevel "bump on bump" or "protuberances on protuberances on protuberances" structure of surface roughness remained largely undeveloped until 1993 when Borodich and Onishchenko [22] introduced the multilevel hierarchical model of roughness. ...
Mathematical modelling of surface roughness is of significant interest for a variety of modern applications, including, but not limited to, tribology and optics. The most popular approaches to modelling rough surfaces are reviewed and critically examined. By providing counterexamples, it is shown that approaches based solely on the use of the fractal geometry or power spectral density have many drawbacks. It is recommended to avoid these approaches. It is argued that the surfaces that cannot be distinguished from the original rough surfaces can be synthesised by employing the concept of the representative elementary pattern of roughness (REPR), i.e., the smallest interval (or area) of a rough surface that statistically represents the whole surface. The REPR may be extracted from surface measurement data by the use of the “moving window” technique in combination with the Kolmogorov–Smirnov statistic.
... The type of canopy impacts the quantity, quality, and distribution of the incoming light. Light is a fundamental force in nature, impacting many interactions such as predator-prey interactions (Spinner et al., 2013), thermoregulation for some species (Refsnider et al., 2018), as well as helping animals navigate their environment and interact with other organisms using eyes/light-sensitive organs (Palmer et al., 2018). Natural fibers have complex profiles consisting of cellulose, hemi-cellulose, lignin, pectin, and other proteins, waxes, and organic molecules (Truss et al., 2016). ...
Climate change has profound effects on drylands, where vegetation like shrubs provide micro-climatic refugia for animals. However, prolonged drought and higher temperatures are reducing the resilience of vegetation. Artificial habitat constructions, such as shelters, may function similarly to shrubs in providing climatic refuge. Natural fabrics, including lignocellulosic fabrics, have gained popularity in conservation due to their biodegradability, lightweight, and strength. In this study, we tested the effects of natural fabric canopies on key desert microclimatic variables , including temperature, relative humidity (RH), and light intensity/radiation to select the best-suited fabric for microclimatic amelioration of resident fauna in future field experiments. We used 0.45 m 2 microsites of burlap, canvas, and nursery fabrics angled to the ground at three repetitions per fabric and paired them with data loggers for 30 days to record near-surface air temperature, RH, and radiation. We compared uncovered and similarly illuminated 0.45 m 2 areas to serve as the control. We saw that the control was consistently the warmest microsite, while burlap and cotton canvas were the coolest. However, burlap offered a lower amplitude of temperature variation compared to cotton canvas. The lowest mean radiation was experienced under burlap and it functioned similarly to cotton canvas when controlling light regimes. We found that nursery fabric showed the highest humidity levels with the lowest variation, while cotton canvas had the lowest humidity and the highest variation. Yet, the high variation in temperature for nursery fabrics suggests it is not ideal for deployment in the field for sheltering resident fauna. Natural fabrics for small shelters could support conservation and management, as they can be deployed, are ecologically friendly, and serve as a stopgap solution for early restoration efforts in sites while vegetation is re-established post-disturbance.
... Black plumage can even have a structural background and absorb more light than black pigmentary feathers (McCoy et al. 2018). Similar effects are known from the dorsal scales of some snake species (Spinner et al. 2013, 2014). Finally, white plumage can result in higher skin temperatures because of increased transmittance and backscattering, when compared to darker plumage (Rogalla et al. 2021). ...
Colour lightness has received considerable attention owing to its diverse functional aspects, such as in thermoregulation, pathogen resistance, and photoprotection. However, the theoretical basis underlying the function of colour lightness is closely related to melanin pigments. Therefore, here we discuss that neglecting other colour-producing mechanisms may bias interpretation of the results. In general, colour lightness is indiscriminately employed as a measure of melanization. Nevertheless, animals may exhibit colours that derive from several pigmentary and structural mechanisms other than melanin. Our primary argument is that colour lightness should not be used indiscriminately before knowing the colour-producing mechanism and validating correlated physiological parameters. For instance, the use of colour lightness as a proxy for thermal or photoprotection function must be validated for pterins, ommochromes, and structural colours.
... Oberh€ autchen features consist of macro-and microstructures such as sharp spines, leaf-like or hexagonal microornamentations and micro-pores (e.g. Alibardi, 2000;Sherbrooke et al., 2007;Spinner et al., 2013). Rain-harvesting lizards often possess hexagonal scale surface microstructures (SSM), also referred to as honeycomb ornamentations by Peterson (1984). ...
Rain‐harvesting behaviour represents an adaptation for water collection that has evolved in some species of iguanian reptiles inhabiting arid environments. To date, such behaviour has been observed only in members of the families Agamidae and Phrynosomatidae. A common set of integumentary features characterizes these rain‐harvesting species, including scale surface microstructures (SSMs), capillary channels and hinge joints. The influence of variations in these features on rain‐harvesting has been a subject of discussion for many decades. Nevertheless, a comprehensive comparative study of similarities and differences between harvesting and non‐harvesting species on a broader scale remains lacking. In this study, we classify scale surface microstructures into three categories: large hexagons (SSM1), smaller nested hexagons (SSM2) and hinge pits (SSM2H). As the first two SSM types are widespread, they do not appear to be directly linked to the adaptation for rain‐harvesting. Conversely, the presence or absence of hinge pits distinguishes harvesters from non‐harvesters. Additionally, channel hierarchy, width and structure determine the effectiveness of the rain‐harvesting architecture. Only Moloch horridus exhibits distinct integumentary features in comparison to other agamids and rain‐harvesting species. Ancestral character state reconstruction suggests that rain‐harvesting behaviour was likely absent in the ancestor of Iguanians, even though overlapping scales and SSM1 were present. Our findings illustrate that rain‐harvesting species have independently converged upon similar structural solutions to address their water acquisition challenges, building upon shared pre‐existing features.
... Hierarchical micro-ornamentation of the West African Gaboon viper's black scales gains pigmental absorbance [6]. The incident light is reflected multiply and scattered by surface irregularities in the nano-and micrometer range, which traps light. ...
Better use of material and energy resources is fundamental in any human activity. Finding better and more sustainable solutions might be inspired by nature herself. The natural evolution of life has shown a successful testing path of sustainable solutions that can be the inspiring starting point for engineering and manufacturing new directions of continuous improvement. This is the role that biomimicry can play. Evolution has been continuously testing this end, thriving strategies with better optimization in its yield. Keeping nature at the center of every design process will lead in the right direction. This is the role that biomimicry can play. Biomimicry or bioinspiration makes the most of the following methodologies: observing how evolution has achieved efficient strategies in any field of interest and realizing how to implement them or having a problem to solve and searching in Nature to find guidance or inspiration to succeed. Through a systematic review of some of the latest developments in manufacturing, focused on their capability to approach (mimic) natural textures; some applications are characterized and tested successfully to reduce energy consumption, improve efficiency, or reduce friction, among other potential improvements. In nature, actual surfaces present a functional texture. Natural evolution has developed textures showing real advantages for different functional purposes. Analyzing those natural surfaces can improve engineering surfaces’ qualitative and quantitative design. A correlation between scales, manufacturing processes, and natural strategies (surface features) will help map new product and engineering design areas of interest. This paper explores these correlations of natural surfaces with functional characteristics that make them sustainable and appropriate for inspiring research directions in manufacturing engineering surfaces. It mainly looks for contributions to efficient energy use in engineered solutions.
... Microstructures focus light onto black pigment to create "super black" or "ultra black" color in peacock spiders , stick insects (Maurer et al., 2017), birds (McCoy et al., 2018, and snakes (Spinner et al., 2013). Ultra-black fish (Davis, Thomas, et al., 2020) and butterflies (Davis, Nijhout, & Johnsen, 2020;Vukusic et al., 2004;Zhao et al., 2011) use nanostructures to increase scattering and, therefore, light absorption by melanin. ...
Carotenoid pigments are the basis for much red, orange, and yellow coloration in nature and central to visual signaling. However, as pigment concentration increases, carotenoid signals not only darken and become more saturated but they also redshift; for example, orange pigments can look red at higher concentration. This occurs because light experiences exponential attenuation, and carotenoid-based signals have spectrally asymmetric reflectance in the visible range. Adding pigment disproportionately affects the high-absorbance regions of the reflectance spectra, which redshifts the perceived hue. This carotenoid redshift is substantial and perceivable by animal observers. In addition, beyond pigment concentration, anything that increases the path length of light through pigment causes this redshift (including optical nano- and microstructures). For example, male Ramphocelus tanagers appear redder than females, despite the same population and concentration of carotenoids, due to microstructures that enhance light-pigment interaction. This mechanism of carotenoid redshift has sensory and evolutionary consequences for honest signaling in that structures that redshift carotenoid ornaments may decrease signal honesty. More generally, nearly all colorful signals vary in hue, saturation, and brightness as light-pigment interactions change, due to spectrally asymmetrical reflectance within the visible range of the relevant species. Therefore, the three attributes of color need to be considered together in studies of honest visual signaling.
... For example, the presence of iridescence in indigo snakes (Drymarchon corais) is attributable to undulating lines or grooves that act as an optical diffraction grating to generate iridescence, which changes color on the surface of the scales based upon the perspective of the observer (Monroe et al., 1968). The velvety black coloration of rhinoceros vipers (Bitis rhinoceros) is due to the presence of complex, leaf-shaped microstructures that permit the reflection of very little light (Spinner et al., 2013). ...
Snakes have evolved extraordinary diversity in coloration, which is strongly linked to fitness and represents a major axis of phenotypic diversity in snakes. In this chapter, we discuss the integrative biology of snake coloration and identify future research targets in the field. First, we explore the ways that researchers define and quantify snake coloration, characterize interspecific diversity, and delimit intraspecific diversity (including ontogenetic color shifts, sexual dichromatism, geographic color variation, and color polymorphism). Second, we synthesize what is known about the mechanisms of the production of coloration in snakes, from identifying the sources of color (pigments or structural color) and color texture (matte and iridescence) to classifying the cells and tissues involved in color and color pattern and describing the quantitative and transmission genetics of snake coloration. Third, we discuss historical and contemporary approaches to studying the functional biology of snake coloration. We achieve this by considering snakes as both signalers and receivers of color information and discussing tradeoffs across the multiple functions of snake coloration, such as thermoregulation and predator defense. Fourth, we examine evidence for the drivers of color evolution by considering the role of neutral and selective forces that impact snake coloration, identifying the ecological agents of selection, and discussing potential evolutionary constraints on coloration in snakes. Finally, we explore macroevolutionary patterns of snake coloration, including phylogenetic tests of color variation, directionality of transitions and rates of change, and ecological correlates of coloration in snakes. Ultimately, future research that unites these conceptual approaches and data across disciplines will be crucial for understanding the factors that structure color variation across the snake tree of life.
... However, on the dorsal scales diverse ultrastructures are observed [2][3][4][7][8][9][10]. Several concepts such as solar radiation reflection through light scattering, dark coloration enhancement, water harvesting and self-cleaning properties have already been proposed to explain the evolution of such structures [2,[20][21][22][23][24]. In general, it can be assumed that snakes optimize their scale ornamentation for adapting to their particular ecological niche [9]. ...
... Light brown is a common skin color of the desert snake. Nevertheless, this color alternates between dark and light grades to reflect sunrays and therefore reduce heat gain [40]. Further, the snake has diamondshaped units covering its entire curved body. ...
Biomimicry inspired architects to solve complex design problems and develop adaptive solutions for enhancing the environmental quality. Fields of inspiration include energy efficiency, natural ventilation, daylighting, and structural stability. In this paper, 144 biomimicry-inspired building skin alternatives have been developed to improve daylighting performance in office buildings in Assiut City, Egypt; 72 alternatives are of 0.5 m frame depth, and other 72 alternatives are of 1.0 m frame depth. Two levels of biomimicry; namely, the organism level (snakeskin) and the behavior level (plants tropism), have been adopted. Alternatives have been developed to be simulated ClimateStudio plug-in for Rhino in accordance with the international rating system leadership in energy and environmental design (LEED v4.1). The evaluation criteria are spatial Daylight Autonomy (sDA), Annual Sunlight Exposure (ASE), Annual Average Lux (AAl), and Spatial Distributing Glare (sDG). An evaluation point system has been developed to evaluate alternatives using Analytical Hierarchy Process (AHP) based on the feedback of 14 faculty of architecture members. Nine building skin alternatives developed succeeded to achieve notable improvement (from 16.69% to 33.73%) compared to the base cases. In general, the 1.0 m frame-depth alternatives achieved better results in improving daylighting performance than the 0.5 m frame-depth alternatives. The most effective parameter in improving daylighting performance was the rotation angle of the skin unit used, to be followed by the distance between the skin and the building façade, the solid-to-void ratio of the skin, the number of units constituting the skin system, and the horizontal bending distance of the skin unit, respectively.
... [11][12][13][14][15][16] In particular, the structural colors observed in organisms are highly interesting for, e.g., sensors, counterfeit protection, or displays applications 17 because they often show extraordinary optical properties. For instance, these biological structural colors include the ultra-black color of the Bitis gabonica, 18,19 the iridescent green coloration of the butterfly Chrysina gloriosa, 20 and the angle-insensitive blue coloration of the butterflies from the genus Morpho, [21][22][23] to name a few. Most organisms, including those mentioned, use hierarchically organized structures at the micro-and nanoscale to generate structural colors. ...
We report on the successful use of three-dimensional (3D) printing by two-photon polymerization to engineer optimized hierarchically composed surface structures at the micro- and nanoscale. The hierarchical composition of the printed structures was inspired by those found on the upper wing surface of blue-winged butterflies from the genus Morpho. In this way, the nanostructures and blue coloration of the organisms was mimicked, but less iridescence was achieved for biomimetic surfaces. Like the biological surface structures, the ones printed exhibited disorders characteristics. As a result, the blue colors generated by biomimetic structures displayed angle-insensitive optical properties similar to those of the Morpho wings. In addition, the great design freedom and simple workflow of the 3D printing technique enabled the fabrication of different structures at the microscale without modifying the dimension of the substructures at the nanoscale. Thus, it was possible to set the direction in which angle-insensitive coloration appeared to an observer. The morphology of biological and biomimetic surface structures was analyzed and compared using scanning electron microscopy. The optical properties of biological and engineered specimens were determined using angle-resolved spectroscopy. Furthermore, the coloration of biomimetic surfaces and the upper wing surface of Morpho butterfly was studied in different liquids. The results were compared, and potential application for biomimetic surfaces was discussed.
