- Pennales
Taxobox
name = Diatoms
image_width = 200px
image_caption = Marine diatoms
domain = Eukaryota
regnum =Chromalveolata
phylum =Heterokont ophyta
classis = Bacillariophyceae
ordo = PennalesOrder Pennales is a traditional subdivision of the
heterokont 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.] . The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. The valves may be linear or oval in shape, and usually bear bilaterally symmetrical ornamental patterns. These patterns are composed of a series of transverse lines (known as striae) that can appear as rows of dots when viewed with anoptical microscope . Some pennate diatoms also exhibit a fissure along their longitudinal axis. This is known as a raphe, and is involved in gliding movements made by diatom cells; motile diatoms always possess a raphe.In terms of
cell cycle , vegetative cells arediploid and undergomitosis during normalcell division . Periodically,meiosis produces morphologically-identicalhaploid gamete s (isogametes), which fuse to produce a (sometimes binucleate)zygote that develops into anauxospore (from which full-size vegetative cells are produced).In some taxonomic schemes, the pennate diatoms are divided into two groups: pennate diatoms without a
raphe (Order Fragilariophyceae), and pennate diatoms with a raphe (Order Bacillariophyceae).
=See also=
*Centrales References
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