Cyanobacteria is any of a large, heterogeneous group of prokaryotic, principally photosynthetic organisms. Cyanobacteria resemble the eukaryotic algae in many ways, including morphological characteristics and ecological niches, and were at one time treated as algae, hence the common name of blue-green algae. Algae have since been reclassified as protists, and the prokaryotic nature of the blue-green algae has caused them to be classified with bacteria in the prokaryotic kingdom Monera. Like all other prokaryotes, cyanobacteria …showed first 75 words of 989 total…

…showed last 75 words of 989 total…have cell walls containing silica or calcium. Three classes are widely recognized (sometimes as separate phyla): Chrysophyceae, the yellow-brown algae; Xanthophyceae, the yellow-green algae; and Bacillariophyceae, the diatoms. They are characterized by the pigment fucoxanthin and oil droplets as the food-reserve Sexual reproduction is rare; a sexual reproduction is by the formation of motile and nonmotile spores and by cell division. Five species that are in this category include Tabellaria, Flagilaria, Melosira, Asterionella and Stephanodiscus.