Cosmarium
Cosmarium spp. · Phytoplankton
Under the microscope · Photo: Petr Knotek / CC BY
Also called Desmid
How to identify Cosmarium
- Under the microscope: single green cells made of two matching halves pinched together in the middle
- Halves are round to oval, smooth or warty
- No spines or arms
- In the water: not visible
Similar species
Staurastrum has arms or points on each half; Closterium is a crescent without a pinched middle.
Profile
| Season | Late spring through fall. |
|---|---|
| Starts | About 55 F and up |
| Light | Moderate to full sun |
| Depth | Open water and among plants |
| How it spreads or reproduces | Cell division, each half grows a new partner half |
| Habitat | Ponds, lakes, bogs and wetlands; many species prefer soft water, others are common in hard water ponds. |
Why it matters in a lake
One of the most common desmids. Harmless; a diverse desmid community usually points to good water quality.
Where it is found
- Idaho: Common
- Oregon: Common
- Wyoming: Common
Classification
| Kingdom | Plantae |
|---|---|
| Phylum | Charophyta |
| Class | Zygnematophyceae |
| Order | Desmidiales |
| Family | Desmidiaceae |
| Scientific name | Cosmarium spp. |
Chlamydomonas
Scenedesmus
Ankistrodesmus
Oocystis
Pediastrum
Desmodesmus
Monoraphidium
Chlorella
Sphaerocystis
ClosteriumNeed a hand?
Want to know what is in your water?
Lab counts of the algae in your lake show what is growing, how much and whether a bloom is coming.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596