- Cyclotella is a small, centric diatom with cells
only 3-5 µm in diameter. The valves are short and drum-shaped.
The circular valve face has rows of areolae radiating from a
distinct central area that is sometimes covered by warts, spines,
or granules. The cells sometimes have long chitinous bristles
that likely help to increase buoyancy or protect the cells from
being consumed by herbivores. Each cell has numerous discoid
plastids. There are about 100 species. Cyclotella meneghiniana
is perhaps the most common species, and has been widely used
in growth experiments.
Some researchers believe that the genus should in fact be subdivided,
and have created new subgenera or species complexes. Additional
phylogenetic research may help to clarify the evolutionary relationships
within the genus Cyclotella, as well as its relationships
to other groups. So far, most researchers agree on only one new
genus, Stephanocyclus, which includes some species that
were formerly part of Cyclotella.
- Like several other centric
diatoms, Cyclotella is able to continue to grow in periods
of sustained darkness by making use of glucose or other dissolved
organic compounds from the environment.