A scanning electron microscope study of the structure and organization of the calcium carbonate deposits of algae

Abstract

The calcium carbonate deposits of Cyanophyte, Charophyte, Chlorophyte, Phaeophyte and Rhodophyte algae have been studied with the scanning electron microscope. The SEM permitted in situ observation of these deposits, which allowed the crystal structure and the organization of the crystalline deposits to be observed. The CaCO₃ was deposited either as argonite or calcite. The CaCO₃ depositing algae can be grouped into three major groups according to the organization and site of deposition of the crystals. The first group (Group A) exhibits extreme organization and the CaCO₃ is deposited on an organic matrix within the cell. The deposits of algae of Group B are formed within the cell wall or mucilage and also show some organization. The deposits of algae of Group C are completely extracellular and exhibit no organization.