Green algae - Pediastrum
The genus Pediastrum is easy to recognize in net sample. The colony is cogwheel- shaped and the single cell is obvious to study. The cells in the periphery are different from the cells in the middle. The outer cells have pin-headed appendages. There are no flagella in the cells.
The diameter of the colony can be up to 200my.
The image on the top is taken from fixed material and the cell wall is clear.
The empty cells, without cell content, have two bright shining bodies, called pyrenoids. The function of the pyrenoid is connected to the starch production. Pediastrum is a common genus in water rich of nutrients.
The smaller image shows the typical green colour of the green-algae group..