title: Microstructural characacterization of shell components in the mollusc Physa sp.
abstract: Shells of the freshwater, pulmonate snail Physa (Mollusca, Gasteropoda), ranging from 0.5 to 10 mm in length, were studied using scanning microscopy, x-ray analysis, and infrared spectroscopy. Results obtained suggest that the shell is composed of aragonite, which occurs in several distinct crystalline forms. A selective distribution of crystalline forms (hexagonal plates, prisms, rhombohedra, and spherulites) occurred along specific sites of the shell. A variable distribution of the forms was also detected in adult shells and in protoconchs of developing embryos. Qualitative elemental analysis, using an energy-dispersive spectrometer, corroborates the presence of calcium, phosphorus and sulphur ions.
authors.affiliation: Labroratory of Electron Microscopy, Institute of Physics, University of São Paulo, São Paulo, Brazil. sipaula@if.usp.br
authors.forename: Silvia M
authors.initials: SM
authors.lastname: de Paula
authors.forename: Marina
authors.initials: M
authors.lastname: Silveira
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002119:Calcium Carbonate / Q000032:analysis* / Q000378:metabolism; D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D008974:Mollusca / Q000033:anatomy & histology* / Q000737:chemistry / Q000648:ultrastructure*; D010758:Phosphorus / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared; D013455:Sulfur / Q000032:analysis; D014961:X-Ray Diffraction
chemical_list: D010758:Phosphorus; D013455:Sulfur; D002119:Calcium Carbonate; D002118:Calcium