Nitzschia sigmoidea

Nitzschia sigmoidea is a large freshwater diatom (microscopic alga) that can be found growing on the surface of mud in ponds and streams.

Large populations of these diatoms can form a golden-brown coating on rocks and sediments, and are often clearly visible on intertidal muds at low tide.

Nitzschia sigmoidea is relatively large and distinctive but still less than 0.5mm long .

Nitzschia sigmoidea was one of the first diatoms to be described in 1817 (as Bacillaria sigmoidea). Later (1853) William Smith (an early British diatomist) created a new genus (Nitzschia) for this species, naming it after Christian Ludwig Nitzsch, the German zoologist who had first found it in Halle, Germany.

Species detail

Cells of N. sigmoidea are more or less sigmoid in girdle view, and linear with wedge-shaped ends in valve view. Cells are about 100-500µm long (0.1-0.5mm), 8-15µm wide in valve view, and about 30µm wide in girdle view. Girdle width varies with the stage of the cell cycle. The raphe keel is slightly off-centre, with irregularly spaced ribs spanning the keel (about 5-7 in 10 µm). Parallel rows of pores cross the valve surface, 23-27 rows in 10µm.The girdle region is formed of several open bands that also contain pores.

Taxonomy

Diatom species are usually identified by the shape and patterns of the silica walls find out more about the identification of N. sigmoidea.
Distribution

Nitzschia sigmoidea is a common widespread diatom discover more about where it is found around the world.
Biology

Diatoms are photosynthetic organisms Learn more about the biology of Nizchia sigmoidea
Reproduction

N. sigmoidea has a unique ways of reproducting. Find out more.
Uses

The fossil remains of diatoms, diatomite or Kieselguhr, have a range of uses, find out more.