Polysaccharides of calcareous algae and their effect on the calcification process

The composition and structure of polysaccharides from several groups of cal careous algae (including calcareous cyanobacteria), which differ in the cal cification mode (extracellular, cell wall, or intracellular), are reviewed, Two families of marine algae, Corallinaceae (Rhodophyta) and Coccolithopho raceae (Prymnesiophyta = Haptophyta), are considered in detail; they exhibi t the cell wall and intracellular calcification modes, respectively, and sy nthesize unusual polysaccharides that seem to directly participate in the c alcification process.