Guide to Identification of
Fresh Water Microorganisms

Microscopic autotrophic organisms (i.e. algae)

 Name

Picture

Characteristic

Taxonomy

Green algae (with flagella, small)
<.05 mm

1. flagella
2. small
3. solitary

4. rapid movement
Phylum Chlorophyceae
i.e. Chlamyolomonas sp.

Green algae (with flagella)
.5-2mm

1. spherical
2. colonial

3. with two flagella
Phylum Chlorophyceae
i.e.  Volvox sp.

Green algae
(no flagella)

 <.5 mm

1. spherical to conical
2. not attached to surface

3. no movement
Phylum Chlorophyceae
i.e. Pediastrum sp.

Filamentous green algae
<.1 mm cms

1. non branching
2. chains of cells with chloroplast

3. no flagella

Phylum Gamophyceae
i.e. Zygnema sp.

Spirogyra
  sp.

Desmids
<.5 mm

1. green
2. no flagella
3. mainly solitary, some colonial
4.various shapes

5. two semi-cell, mirror image

Phylum Gamophyceae
i.e. Desmidium sp

Closterium
sp.

Diatoms
<.5 mm

1. one cell
2. slow gliding motion
3. solitary or colonial

4.cell wall (frustules) made of silica

Phylum Bacillariophyceae
i.e. Pennales, Centric

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