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Diatoms
Isthmia nervosa
Scientific classification
Domain:	Eukaryota
(unranked):	SAR
Superphylum:	Heterokonta
Phylum:	Bacillariophyta
Class:	Coscinodiscophyceae
Suborders
Biddulphiophycidae Chaetocerotophycidae Corethrophycidae Coscinodiscophycidae Cymatosirophycidae Lithodesmiophycidae Rhizosoleniophycidae Thalassiosirophycidae

The Coscinodiscophyceae are a class(s) of diatoms. They are similar to the Centrales, a traditional, paraphyletic subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view. The valves often bear radially symmetrical ornamental patterns that can appear as dots when viewed with an optical microscope. Some also bear spines on their valves, which may either increase cell surface area and reduce sinking, or act as a deterrent to zooplankton grazers. Unlike pennate diatoms, centric diatoms never have a raphe.

In terms of cell cycle, vegetative cells are diploid and undergo mitosis during normal cell division. In sexual species, oogamous meiosis produces haploid gametes, either ova or sperm cells. These fuse to produce a zygote which expands in size to develop into an auxospore from which full-sized vegetative cells are produced.

In some taxonomy schemes, the centric diatoms are known instead as order Coscinodiscophyceae, and in some schemes as order Biddulphiales. However, diatom taxonomy is changing due to the development of new molecular and genetical analysis tools.

See also

• Pennales

References

1. Cattolico RA, Jacobs MA, Zhou Y, et al. (2008). "Chloroplast genome sequencing analysis of Heterosigma akashiwo CCMP452 (West Atlantic) and NIES293 (West Pacific) strains". BMC Genomics. 9: 211. doi:10.1186/1471-2164-9-211. PMC 2410131. PMID 18462506.
2. Hoek, Christiaan; Mann, David; Jahns, H.M. (1995). Algae: An Introduction to Phycology. Cambridge University Press. ISBN 978-0-521-31687-3.
3. ^ Round, F.E.; Crawford, R.M.; Mann, D.G. (4 December 2007). Diatoms: Biology and Morphology of the Genera. Cambridge University Press. ISBN 978-1-107-39313-4.
4. ^ Williams, D.M.; Kociolek, J.P. (2007). "Pursuit of a natural classification of diatoms: History, monophyly and the rejection of paraphyletic taxa". European Journal of Phycology. 42 (3): 313–9. doi:10.1080/09670260701419921.
5. Tomas, Carmelo R., ed. (1997). Identifying Marine Phytoplankton. Academic Press. ISBN 978-0-08-053442-8.

Further reading

Tremarin, Priscila; Veiga Ludwig, Thelma Alvim; Torgan, Lezilda Carvalho (November 7, 2014). "Aulacoseira veraluciae sp. nov. (Coscinodiscophyceae, Aulacoseiraceae): a common freshwater diatom from Brazil". Phytotaxa. 184 (4): 208–222. doi:10.11646/phytotaxa.184.4.2.

External links

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• Coscinodiscophyceae
• Ochrophyte classes