Asterionella. Asterionella is a genus of pennate freshwater diatoms.
They are frequently found in star shaped colonies of individuals. Description[edit] Asterionella average cell size is 60-80 micrometer long and 2-4 micrometer wide. Asterionella formosa. Asterionella japonica. Fragilaria. Fragilaria capucina. Diatom. General biology[edit] A diatom.
Numbered graduations are 10 micrometres apart. What are Diatoms? General Information The division Bacilliariophyta is distinguished by the presence of an inorganic cell wall composed of silica (hydrated Si02).
The wall, or frustule, consists of two parts called “valves”. Diatoms have evolved to have elaborate silica cell walls that reflect the types of habitat to which the particular species is adapted. Diatoms are abundant in nearly every habitat where water is found – oceans, lakes, streams, mosses, soils, even the bark of trees. Diatoms. Species.