Ultrastructure and Deposition of Silica in the Chrysophyceae

Abstract

The Chrysophyceae, sometimes known as the golden-brown algae, are a group of motile, unicellular, colonial, coccoid, and filamentous algae predominantly found in freshwater habitats, although marine and brackish-water species are known (Parke and Dixon, 1976). The majority are characterized by their distinctive pigment composition (Hibberd, 1976), heterokont flagellation of motile cells, protoplast structure, and their capacity for the endogenous deposition of silica. Silica is laid down either in the form of scales, in a relatively small number of species, or in many species, as the walls of cysts, the form of which is one of the group’s most characteristic features (Christensen, 1962; Fritsch, 1956; Hibberd, 1976; Pascher, 1914, 1925, 1931).