title: Sea urchin spine calcite forms via a transient amorphous calcium carbonate phase.
abstract: The skeletons of adult echinoderms comprise large single crystals of calcite with smooth convoluted fenestrated morphologies, raising many questions about how they form. By using water etching, infrared spectroscopy, electron diffraction, and environmental scanning electron microscopy, we show that sea urchin spine regeneration proceeds via the initial deposition of amorphous calcium carbonate. Because most echinoderms produce the same type of skeletal material, they probably all use this same mechanism. Deposition of transient amorphous phases as a strategy for producing single crystals with complex morphology may have interesting implications for the development of sophisticated materials.
authors.affiliation: Department of Structural Biology, 76100 Rehovot, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Politi
authors.forename: Talmon
authors.initials: T
authors.lastname: Arad
authors.forename: Eugenia
authors.initials: E
authors.lastname: Klein
authors.forename: Steve
authors.initials: S
authors.lastname: Weiner
authors.forename: Lia
authors.initials: L
authors.lastname: Addadi
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D003460:Crystallization; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D012038:Regeneration; D012617:Sea Urchins / Q000033:anatomy & histology / Q000502:physiology*; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002119:Calcium Carbonate