Nanostructures and Monolayers of Spheres Reduce Surface Reflections in Hyperiid Amphipods
| Autor: | Laura E. Bagge, Karen J. Osborn, Sönke Johnsen |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Light 02 engineering and technology Biology Zooplankton General Biochemistry Genetics and Molecular Biology Light scattering 03 medical and health sciences Optics Species Specificity Animal Shells Monolayer Animals Amphipoda Vision Ocular business.industry Ecology Extremities 021001 nanoscience & nanotechnology biology.organism_classification Ray Wavelength 030104 developmental biology Microscopy Electron Scanning Reflection (physics) 0210 nano-technology General Agricultural and Biological Sciences business Refractive index Light field Phronima |
| Zdroj: | Current Biology. 26:3071-3076 |
| ISSN: | 0960-9822 |
| DOI: | 10.1016/j.cub.2016.09.033 |
| Popis: | Summary Transparent zooplankton and nekton are often nearly invisible when viewed under ambient light in the pelagic zone [1–3]. However, in this environment, where the light field is directional (and thus likely to cause reflections), and under the bioluminescent searchlights of potential predators, animals may be revealed by reflections from their body surface [4–7]. We investigated the cuticle surfaces of seven species of hyperiids (Crustacea; Amphipoda) using scanning electron microscopy and found two undocumented features that may reduce reflectance. We found that the legs of Cystisoma spp. (n = 5) are covered with an ordered array of nanoprotuberances 200 ± 20 nm SD in height that function optically as a gradient refractive index material [6, 8, 9]. Additionally, we observed that Cystisoma and six other species of hyperiids are covered with a monolayer of homogenous spheres (diameters ranging from 52 ± 7 nm SD on Cystisoma spp. to 320 ± 15 nm SD on Phronima spp.). Optical modeling using effective medium theory and transfer matrix methods demonstrated that both the nanoprotuberances and the monolayers reduce reflectance by as much as 100-fold, depending on the wavelength and angle of the incident light and the thickness of the gradient layer. Even though we only consider surface reflectance and not internal light scattering, our study demonstrates that these nanoprotuberances and spheres can improve crypsis in a featureless habitat where the smallest reflection can render an animal vulnerable to visual predation. |
| Databáze: | OpenAIRE |
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