Cells are many times longer than wide, and are variously needle-shaped, sickle-shaped, or sigmoid in outline.

[2] The distinctions between the genera are artificial, since they do not correspond with monophyletic groupings;[7] occasionally, Ankistrodesmus is found as single cells.

[3] Identification of species chiefly depends on details of the size and shape of cells.

[2] However, a molecular phylogenetic study has shown evidence of considerable cryptic diversity.

[8] Some strains of Ankistrodesmus are promising candidates for biodiesel production, or for producing fatty acids on a commercial scale.