Monterey Bay Aquarium Research Institute
Marine Botany



Centrales, or centric diatoms, are typically round but take on a variety of interesting and beautiful shapes. They may be three- or four-cornered or even star-shaped. They may be distinguished from pennate forms by radial symmetry: their shells, or tests, seem to radiate from a central point. This symmetry is easy to see in the pattern of a diatom's areolae.

Centric diatoms tend to prefer marine habitats over freshwater, and are more common floating as phytoplankton. Most of the pictures in my photo library are of centrales. Common forms off the coast of central California in winter include Coscinodiscus, Chaetoceros colonies, Biddulphia, Skeletonemia colonies, Thallasionema, and Bacteriastrum.

Diatom Main Menu
Anatomy and Morphology
My Photo Library
copyright John Becker 1996.

Last updated: Feb. 05, 2009