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Moving cilia create iridescence: comb jellies


Comb jelly / NOAA Photo G.. / LicensePD - Public Domain

Locomotory cilia on the comb rows of the comb jelly Beroë cucumis produce colors by reflecting white light using two-dimensional photonic crystals.

"Ctenophores, comb-jellies or comb-jellyfishes, are common names for marine animals of the phylum Ctenophora. All parts of their deformable body, including muscles, are transparent. The refractive index of their tissues matches nearly exactly that of the salted water in which they live, consequently they are difficult to perceive, except under intense illumination, when the irregularities of their outer membrane produce some faint light scattering. The species Beroë cucumis has the form of oblong ellipsoids (a “cucumber” shape) with a mouth aperture in the forward swimming direction. Eight rows of locomotory cilia run along the body of the animal...These organs are usually much more easily visible than the rest of the body surface, due to the stronger light scattering which takes place on these protrusions. Moreover, the “comb”-rows appear to be brightly colored, showing an iridescence that rainbows across the whole visible spectrum as the combs beat for locomotion. As the rest of the paper will make clear, this is not related to any bioluminescence but can be understood as selective reflection from a two-dimensional photonic-crystal." (Welch et al. 2006:041916-1)
About the inspiring organism
Med_lightrefractsof_combrows_of_ctenophore_mertensia_ovum Beroe cucumis
Beroe cucumis Fabricius, 1789 p.p.

Learn more at
Some organism data provided by: URMO: UNESCO-IOC Register of Marine Organisms
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Color displays optically powered by ambient light, thus working better outdoors. Superimpose transparent structures on ordinary, electroluminescent pixels to also allow use indoors.

Industrial Sector(s) interested in this strategy: Manufacturing, lighting

Laboratoire de Physique du Solide
Marie Rassart, Jean-Pol Vigneron, Jean-François Colomer
University of Namur
Welch V; Vigneron JP; Lousse V; Parker A. 2006. Optical properties of the iridescent organ of the comb-jellyfish Beroë cucumis (Ctenophora). Physical Review E. 73(4): 0419161-041916-7.
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