Domain Eukarya/Heterokonts Diatoms Link to diatom image directory Eukaryotic, photosynthetic organisms with chlorophylls a and c. Mostly unicellular though some form filaments and loose colonial aggregations. Their walls are made of silicon and consist of two parts that connect together like a pill box. The face-view of a cell encompassing an entire part is a valve-view, a view showing where these parts overlap is a girdle-view. These organisms are the most important primary producers in the world's waters.   return

Pennate diatoms

Are bilaterally symmetrical in valve-view. Many are motile when in contact with a substrate, and live in sediments, on rocks ect. and, hence, are important primary producers in shallow waters.

Centric diatoms

Are radially symmetrical in valve-view. Are typically part of the planktonic community, hence, are important producers in deep waters such as ocean environments.

Movies

• Of a pennate diatom knocked over from a valve view to a girdle view by Oscillatoria
• Of freshly collected pennate diatoms moving around the slide