The
diatoms are an extremely abundant group in both fresh and marine environments.
Generally they are green or brown in color and as you might guess, carry
out photosynthesis.
One unusual feature is that the cells are surrounded by a test or skeleton made out of silicon dioxide. When diatoms die, over geological time the tests form vast deposits of so called diatomaceous earth. This substance is used as an abrasive and polish and is still found occasionally in tooth paste. Its regular use as a dental polish is frowned upon though as it can damage the enamel.
These cells are capable of gliding over surfaces, but how they do it is not yet well understood.
This
diatom shows small slits especially along the right margin of the cell.
Its believe that the cell secretes a fluid through these slits over which
the organism glides. 6/13/99
pgd revised 2/17/01