title: Structural Basis for the Brilliant Colors of the Sapphirinid Copepods.
abstract: Males of sapphirinid copepods use regularly alternating layers of hexagonal-shaped guanine crystals and cytoplasm to produce spectacular structural colors. In order to understand the mechanism by which the different colors are produced, we measured the reflectance of live individuals and then characterized the organization of the crystals and the cytoplasm layers in the same individuals using cryo-SEM. On the basis of these measurements, we calculated the expected reflectance spectra and found that they are strikingly similar to the measured ones. We show that variations in the cytoplasm layer thickness are mainly responsible for the different reflected colors and also that the copepod color strongly depends on the angular orientation relative to the incident light, which can account for its appearance and disappearance during spiral swimming in the natural habitat.
authors.forename: Dvir
authors.initials: D
authors.lastname: Gur
authors.forename: Ben
authors.initials: B
authors.lastname: Leshem
authors.forename: Maria
authors.initials: M
authors.lastname: Pierantoni
authors.affiliation: §The Interuniversity Institute for Marine Sciences, Eilat 88103, Israel.
authors.forename: Viviana
authors.initials: V
authors.lastname: Farstey
authors.forename: Dan
authors.initials: D
authors.lastname: Oron
authors.forename: Steve
authors.initials: S
authors.lastname: Weiner
authors.forename: Lia
authors.initials: L
authors.lastname: Addadi
mesh_terms: D000818:Animals; D003116:Color; D033342:Copepoda / Q000502:physiology*; D020285:Cryoelectron Microscopy; D003460:Crystallization; D003593:Cytoplasm / Q000378:metabolism; D017753:Ecosystem; D006147:Guanine / Q000737:chemistry; D008027:Light; D008297:Male; D008855:Microscopy, Electron, Scanning; D017785:Photons
chemical_list: D006147:Guanine