- Centrales
Taxobox
name = Diatoms
image_width = 200px
image_caption = Marine diatoms
domain = Eukaryota
regnum =Chromalveolata
phylum =Heterokont ophyta
classis = Bacillariophyceae
ordo = Centrales
subdivision_ranks = Suborders
subdivision =
*Coscinodiscineae
*Rhizosoleniineae
*Biddulphiineae Order Centrales is a traditional,
paraphyletic subdivision of theheterokont algae known asdiatom sHoek, C. van den, Mann, D. G. and Jahns, H. M. (1995). " [http://books.google.co.uk/books?id=xuUoiFesSHMC&printsec=frontcover Algae : An introduction to phycology] ", Cambridge University Press, UK.] Round, F. E. and Crawford, R. M. (1990). "The Diatoms. Biology and Morphology of the Genera", Cambridge University Press, UK.] . 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, 313-319.] 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 anoptical microscope . Some also bear spines on their valves, which may either increase cell surface area and reduce sinking, or act as a deterrant tozooplankton grazers. Unlike pennate diatoms, centric diatoms never have a raphe.In terms of
cell cycle , vegetative cells arediploid and undergomitosis during normalcell division . In sexual species, oogamousmeiosis produceshaploid gamete s, either ova orsperm cell s. These fuse to produce azygote which expands in size to develop into anauxospore from which full-size vegetative cells are produced.In some
taxonomy schemes, the centric diatoms are known instead as Order Coscinodiscophyceae. And in some schemes as order Biddulphiales Tomas, C. R., Hasle G. R., Syvertsen, E. E., Steidinger, K. A., Tangen, K., Throndsen, J., Heimdal, B. R., (1997). "Identifying Marine Phytoplankton", Academic Press.] . However, diatom taxonomy is changing due to the development of new molecular and genetical analysis tools.ee also
*
Pennales References
Wikimedia Foundation. 2010.