Many species rely on diverse selections of entirely organic photonic structures for the manipulation of light and the display of striking colours. Here we report the discovery of a mineralized hierarchical photonic architecture embedded within the translucent shell of the blue-rayed limpet Patella pellucida. The bright colour of the limpet’s stripes originates from light interference in a periodically layered zig-zag architecture of crystallographically co-oriented calcite lamellae. Beneath the photonic multilayer, a disordered array of light-absorbing particles provides contrast for the blue colour. This unique mineralized manifestation of a synergy of two distinct optical elements at specific locations within the continuum of the limpet’s translucent protective shell ensures the vivid shine of the blue stripes, which can be perceived under water from a wide range of viewing angles. The stripes’ reflection band coincides with the spectral range of minimal light absorption in sea water, raising intriguing questions regarding their functional significance.
We gratefully acknowledge the help of Ruben Chapela, Christopher Earing, Edward Blum, Mathilde Bue and Stuart Jenkins with the collection of specimen. We thank Professor Ullrich Steiner and Dr Katherine Thomas for their support in the initial project stages and Dr Stefan Guldin for help with the whole-shell powder X-ray diffraction measurements (see Supplementary Information). We would like to thank Professor PUPA Gilbert and Ian Olson for general discussion, Dr Shiahn Chen and Dr Yong Zhang for their technical assistance in electron microscopy and Dr Steve Wang for his support at beamline 32-ID at the Advanced Photon Source. Pellucida morph and nudibranch photographs, displayed in Fig. 7 were kindly provided by Larry Friesen, Josep Lluis Peralta and Jim Anderson. M.K. and J.A. gratefully acknowledge the support of the US Air Force Office of Scientific Research Multidisciplinary University Research Initiative (FA9550-09-1-0669-DOD35- CAP). L.L. and C.O. gratefully acknowledge the support of the National Science Foundation MIT Center for Materials Science and Engineering (DMR-0819762), and the National Security Science and Engineering Faculty Fellowship Program (N00244-09-1- 0064). M.K. acknowledges the financial support from the Alexander von Humboldt Foundation in form of a Feodor Lynen postdoctoral research fellowship. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.