Navicula

Navicula radiosa

Navicula is a genus of diatoms ( Bacillariophyta ) and comprises around 250 species. Navicula is the diminutive of the Latin navis, meaning " boat ".

Features

The representatives are small, boat-, single-celled algae. The trays are rectangular in side view, in valve view they are schiffchenförmig. A cell containing two plastids without pyrenoids. They are elongated and colored golden brown due to the fucoxanthin. The plastids are at the belt straps. Some species have H-shaped plastids. The edge of the plastids is always smooth. The nucleus is situated in the center of the cell. The two shells have centered a clearly developed raphe. The shell is finely structured, in the center of a circular area is without structures. The cells are capable of rapid creep over the substrate. The size ranges from 5 to 70 microns.

Asexual reproduction occurs by the typical dichotomy of diatoms. Sexual reproduction takes place by isogamy, with a gamete is formed per cell. After cell fusion results in the formation of a auxospore and thereby to cell enlargement.

The species differ in cell shape, cell size, and the shape of the shell characteristics plastids.

Occurrence

Navicula occur on the substrate in all water types.

Documents

• K.-H. Linne von Berg, K. Hoef -Emden, B. Marin, M. Melkonian: The Cosmos algae leader. The main freshwater algae under the microscope. Kosmos, Stuttgart 2004, pp. 222, ISBN 3-440-09719-6