Core-shell nanospheres behind the blue eyes of the bay scallop Argopecten irradians.

Published

Journal Article

The bay scallop Argopecten irradians (Mollusca: Bivalvia) has dozens of iridescent blue eyes that focus light using mirror-based optics. Here, we test the hypothesis that these eyes appear blue because of photonic nanostructures that preferentially scatter short-wavelength light. Using transmission electron microscopy, we found that the epithelial cells covering the eyes of A. irradians have three distinct layers: an outer layer of microvilli, a middle layer of random close-packed nanospheres and an inner layer of pigment granules. The nanospheres are approximately 180 nm in diameter and consist of electron-dense cores approximately 140 nm in diameter surrounded by less electron-dense shells 20 nm thick. They are packed at a volume density of approximately 60% and energy-dispersive X-ray spectroscopy indicates that they are not mineralized. Optical modelling revealed that the nanospheres are an ideal size for producing angle-weighted scattering that is bright and blue. A comparative perspective supports our hypothesis: epithelial cells from the black eyes of the sea scallop Placopecten magellanicus have an outer layer of microvilli and an inner layer of pigment granules but lack a layer of nanospheres between them. We speculate that light-scattering nanospheres help to prevent UV wavelengths from damaging the internal structures of the eyes of A. irradians and other blue-eyed scallops.

Full Text

Duke Authors

Cited Authors

  • Harris, OK; Kingston, ACN; Wolfe, CS; Ghoshroy, S; Johnsen, S; Speiser, DI

Published Date

  • October 23, 2019

Published In

Volume / Issue

  • 16 / 159

Start / End Page

  • 20190383 -

PubMed ID

  • 31640501

Pubmed Central ID

  • 31640501

Electronic International Standard Serial Number (EISSN)

  • 1742-5662

International Standard Serial Number (ISSN)

  • 1742-5689

Digital Object Identifier (DOI)

  • 10.1098/rsif.2019.0383

Language

  • eng