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Consequently, diatoms are ranked anywhere from a class, usually called Diatomophyceae or Bacillariophyceae, to a division (=phylum), usually called Bacillariophyta, with corresponding changes in the ranks of their subgroups.
For many years the diatoms—treated either as a class (Bacillariophyceae) or a phylum (Bacillariophyta)—were divided into just 2 orders, corresponding to the centric and the pennate diatoms (Centrales and Pennales; alternative names Biddulphiales and Bacillariales, as used e.g. in Lee, 1989). [9]
Within the diatoms (Bacillariophyta), harmful effects can be due to physical damage or to toxin production. Centric diatoms like Chaetoceros live as colonial chains of cells with long spines (setae) that can clog fish gills, causing their death.
Bacillaria paxillifer was originally described under the name Vibrio paxillifer by Otto Frederick Müller in 1786. It is the first diatom species known to be described. [5] It was separately described two years later (1788) by Johann Friedrich Gmelin as Bacillaria paradoxa.
The native range of Thalassiosira weissflogii is unclear, but it is found in marine, brackish and freshwater environments. It seems to grow best at higher salinities [6] and occurs in coastal waters in the Atlantic and Pacific Oceans and in rivers and lakes in Europe, Asia, South and North America, including the Great Lakes, where it was thought to have been introduced in ballast water.
Bacteriastrum is a widely distributed marine, planktonic genus. This genus is often associated with Chaetoceros but differs in radial symmetry and fenestration of setae. The colonies tend to lie in girdle view, and the cells are separated by the curvature of the basal part of the setae, leaving a small gap between the cells.
Cyclotella is a genus of diatoms often found in oligotrophic environments, both marine and fresh water. It is in the family Stephanodiscaceae and the order Thalassiosirales. [1]
A few other groups may be included in the Cercozoa, but some trees appear closer to the Foraminifera. These are the Phytomyxea and Ascetosporea, parasites of plants and animals, respectively, and the peculiar amoeba Gromia. The different groups of Rhizaria are considered close relatives based mainly on genetic similarities, and have been ...