Coscinodiscales

Centric diatom, seen from valve view. This is an empty frustule of a large marine species. The pattern of pores in the frustule is used in identification. Marine. Phase contrast.

Coscinodiscus (coss-co-no-disc-us) a centric diatom, seen from valve view. This is an empty frustule of a large marine species. The pattern of pores in the frustule is used in identification. Marine. Phase contrast.

Coscinodiscus (a centric diatom), seen from valve view. This is an empty frustule of a large marine species. The pattern of pores in the frustule is used in identification. Marine. Differential interference contrast.

Coscinodiscus (caw-skin-owe-disk-us) a centric diatom (stramenopile), this genus is common in the marine plankton and has hundreds of species, some of which can achieve a very large size. The cell to the left is in girdle view, with the two valves visible to either end and girdle bands in the middle of the cell, the cell to the right is seen from valve (end) view. This genus has small thickenings (processes) around the margin of the valve. The species are mostly distinguished by the pattern of sculpting of the frustule. Differential interference microscopy. data on this strain.

Cells of this centric diatom observed in the water column from Lake Pontchartrain, differential interference contrast optics.

This large flat centric diatom is commonly found in the waters off Martha's Vineyard. This is a phase contrast image by D J Patterson and D Lahr.

This species is easily identified by its hexagonal central area and its division into usually six sectors with alternating raised and depressed areas. It is a cosmopolitan species andcan be abundant in cold to temperate coastal waters

C. radiatus is one of the smaller Coscinodiscus species. It is box shaped in girdle view and the valves are very flat. The areolae form disctinct rows radiating from the valve centre. C. radiatus is a cosmopolitan species.

Scanning electron microscope image of valve. The organism is tentatively identified as C. radiatus. Sample taken from the water column off Martha's Vineyard, Massachusetts. Image by Charley O'Kelly and Shauna Murray.

Scanning electron micrograph showing detail of the frustule of this diatom. The larger depressions are called areolae, and perforated region is called the cribrum, within which each perforation is referred to as a cribellum. The same term probably also refers to the perforations in the margins of the areolae. The species is probably C. radiatus. Sample from the water column off Martha's Vineyard. Images by Charley O'Kelly and Shauna Murray.  

This species has a very fine aerolation. It can be distinguished from other species by the central hyaline area and the hyaline lines radiating from it between the areolae. It also has a distinctive shape in girdle view. The valve is very high (often higher than wide) and the valve margin appears to undulate slightly.

SEM of girdle view. The ligulae which fit in the open girdle bands are weakly visible. Scale bar indicates 100 µm.  Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.  

Closeup of the lateral side of the valve. Scale bar indicates 25 µm.  Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.  

Valvar View. Scale bar indicates 100 µm.  Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.  

Closeup showing hyaline central area. Scale bar indicates 10 µm. Sample from North Sea near Heligoland (spring diatom bloom). Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.  

Closeup showing fine structure of valvar pores. Scale bar indicates 5 µm.  Sample from North Sea near Heligoland (spring diatom bloom). Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.  

Actinoptychus heliopelta.