A small group of unicellular protists, sometimes regarded as algae (class Cryptophyceae) and sometimes as protozoa (class Phytomastigophora). The cells are typically dorsoventrally flattened, lack a cell wall, and have 2 flagella of equal length. Most species are photosynthetic, but a few are colourless and heterotrophic. Sexual reproduction is unknown. They are found in freshwater and marine habitats.
Subjects: Plant Sciences and Forestry.