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(phycology) Any of a group of algae characterized by their siliceous covering and symmetry, mostly are aquatic, being found in fresh, brackish, and salt water


Diatoms are a major group of microscopic algae and are among the most common types of phytoplankton. Most diatoms are unicellular, although some form chains or simple colonies. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica. These walls show a wide diversity in form, some quite beautiful and ornate, but usually consist of two symmetrical sides with a split between them, hence the group name.

Diatoms were previously grouped together with the yellow-green and golden brown algae to Phylum Chrysophyta.1 More recent system of classifications place the diatoms to Phylum Bacillariophyta of supergroup Chromista, and includes the following taxonomic orders: Bacillariophceae incertae sedis, Bacillariophyceae, Coscinodiscophyceae, and Fragilariophyceae.2 Ongoing research and studies on these species though may lead to future changes in their taxonomic positions.

Word origin: Ancient Greek diá (“through”) + témnein (“to cut”)

Scientific classification:

Other common name(s):

  • bacillariophyte

See also:

1 Pascher, A. (1914). "Über Flagellaten und Algen ". Berichte der deutsche botanischen Gesellschaft 32: 136–160.
2 Bacillariophyta. Retrieved from [[1]].