Dramatic colour changes in a bird of paradise caused by uniquely structured breast feather barbules

Stavenga, Doekele G.; Leertouwer, Hein L.; Marshall, N. Justin; Osorio, Daniel

doi:10.1098/rspb.2010.2293

Cited by 116 publications

(133 citation statements)

References 32 publications

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“…22 Consequently, when the melanin is periodically arranged, strong photonic effects can emerge. This possibility is exploited by many animals, e.g., in bird feathers [23][24][25] and beetle cuticles 26,27 (see also Refs. 28 and 29).…”

Section: Refractive Index and Absorption Coefficientmentioning

confidence: 99%

Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin–Lebedeff interference microscopy

2013

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Jamin-Lebedeff polarizing interference microscopy is a classical method for determining the refractive index and thickness of transparent tissues. Here, we extend the application of this method to pigmented, absorbing biological tissues, based on a theoretical derivation using Jones calculus. This novel method is applied to the wings of the American Rubyspot damselfly, Hetaerina americana. The membranes in the red-colored parts of the damselfly's wings, with a thickness of 2.5 mm, contain a pigment with maximal absorption at 490 nm and a peak absorbance coefficient of 0.7 mm 21 . The high pigment density causes a considerable and anomalous dispersion of the refractive index. This result can be quantitatively understood from the pigment absorbance spectrum by applying the Kramers-Kronig dispersion relations. Measurements of the spectral dependence of the refractive index and the absorption are valuable for gaining quantitative insight into how the material properties of animal tissues influence coloration.

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Section: Refractive Index and Absorption Coefficientmentioning

confidence: 99%

Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin–Lebedeff interference microscopy

2013

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“…In Lawes's Parotia (Parotia lawesii), the barbules of the males' breast feathers have a boomerang-shaped cross-section, which produces three directional-colored reflectors. 5 Here we investigate the male Parotia's occipital (or nape) feathers, which produce a shiny, silvery patch ( Figure 1a and 1b). Compared to the breast feathers they are less colorful, but the barbules of the occipital feathers exhibit a mirror-like, directional reflection due to nanostructured melanin.…”

Section: Introductionmentioning

confidence: 99%

High refractive index of melanin in shiny occipital feathers of a bird of paradise

et al. 2015

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Male Lawes's Parotia, a bird of paradise, use the highly directional reflection of the structurally colored, brilliant-silvery occipital feathers in their courtship display. As in other birds, the structural coloration is produced by ordered melanin pigmentation. The barbules of the Parotia's occipital feathers, with thickness ,3 mm, contain 6-7 layers of densely packed melanin rodlets (diameter ,0.25 mm, length ,2 mm). The effectively ,0.2 mm thick melanin layers separated by ,0.2 mm thick keratin layers create a multilayer interference reflector. Reflectance measurements yielded peak wavelengths in the near-infrared at ,1.3 mm, i.e., far outside the visible wavelength range. With the Jamin-Lebedeff interference microscopy method recently developed for pigmented media, we here determined the refractive index of the intact barbules. We thus derived the wavelength dependence of the refractive index of the barbules' melanin to be 1.7-1.8 in the visible wavelength range. Implementing the anatomical and refractive index data in an optical multilayer model, we calculated the barbules' reflectance, transmittance and absorptance spectra, thereby confirming measured spectra. Keywords: bird of paradise; interference reflector; iridescence; Jamin-Lebedeff microscopy; multilayer INTRODUCTIONIn animal integuments melanins commonly produce dull red, brown and black colors. With nanoscale order, melanin in a matrix of vertebrate keratin or arthropod chitin can produce striking structural colors. [1][2][3][4] The magnificent displays of birds of paradise exemplify how the fine branches of the bird feathers, the barbules, are modified to achieve a diverse range of visual effects through structural coloration. In Lawes's Parotia (Parotia lawesii), the barbules of the males' breast feathers have a boomerang-shaped cross-section, which produces three directional-colored reflectors. 5 Here we investigate the male Parotia's occipital (or nape) feathers, which produce a shiny, silvery patch (Figure 1a and 1b). Compared to the breast feathers they are less colorful, but the barbules of the occipital feathers exhibit a mirror-like, directional reflection due to nanostructured melanin. 6 The uniquely colorful breast feathers allows the breast color to switch sharply between yellow, blue and black as the bird moves, during the ballerina dance, which is performed as part of the courtship display. [7][8][9] The shiny occipital feathers have a similar function. Recent behavioral observations on the closely related Wahnes's Parotia demonstrate that the occipital feather reflections are sharply directed to the observing females during part of the courtship performance, presumably to impress a potential mate, viewing from an elevated position on a tree branch. [6][7][8][9][10] To unravel the optical basis of the shiny occipital reflectors, we investigated the barbule anatomy. This revealed very regularly arranged melanosomes, i.e., small melanin rodlets, arranged in layers. To achieve an in-depth, quantitative understanding of the feathers'

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“…the well-known multi-layers. They create the metallic and polarized reflections of, for example, the skin of cephalopods [9] and fishes [11], the elytra of jewel beetles [12 -15], scarabs [16,17], and the breast feathers of birds of paradise [18]. Two-dimensional photonic crystals, that is, structures with periodicity in two dimensions, underlie the coloration of peacock feathers [19,20].…”

Section: Introductionmentioning

confidence: 99%

Brilliant camouflage : photonic crystals in the diamond weevil, Entimus imperialis

et al. 2012

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The neotropical diamond weevil, Entimus imperialis, is marked by rows of brilliant spots on the overall black elytra. The spots are concave pits with intricate patterns of structural-coloured scales, consisting of large domains of three-dimensional photonic crystals that have a diamond-type structure. Reflectance spectra measured from individual scale domains perfectly match model spectra, calculated with anatomical data and finite-difference time-domain methods. The reflections of single domains are extremely directional (observed with a point source less than 58), but the special arrangement of the scales in the concave pits significantly broadens the angular distribution of the reflections. The resulting virtually angle-independent green coloration of the weevil closely approximates the colour of a foliaceous background. While the closedistance colourful shininess of E. imperialis may facilitate intersexual recognition, the diffuse green reflectance of the elytra when seen at long-distance provides cryptic camouflage.

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Dramatic colour changes in a bird of paradise caused by uniquely structured breast feather barbules

Cited by 116 publications

References 32 publications

Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin–Lebedeff interference microscopy

Quantifying the refractive index dispersion of a pigmented biological tissue using Jamin–Lebedeff interference microscopy

High refractive index of melanin in shiny occipital feathers of a bird of paradise

Brilliant camouflage : photonic crystals in the diamond weevil, Entimus imperialis

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