Guide to Identification of
Fresh Water Microorganisms

Other fresh water plankton (Animalia, Monera, etc)

 Name

Picture

Characteristic

Taxonomy

Blue-green algae
(cyanobacteria)

1. blue green color
2. gliding movement
3. prokaryote

Kingdom Monera
i.e.  Annabella sp.

Euglenoids
<.4mm

1. sometimes green
2, flagellate

3. red eye spot

Phylum Euglenida
i.e. Euglena sp.

Dinoflagellates
<.4mm

1. free swimming
2. tough armor
3. flagellate

4. autotrophic, heterotrophic
Phylum Dinoflagellate

Rotifers
.4mm - 2 cm

1. corona with cilia
2. hairy appendages
3. transparent with lorica
4. free swimming or attached
5. organs, compressed body

Phylum Rotifer
Class Bdelloided

Class Monogononta

Hydra
2 cm

1. green brown or colorless
2. body and tentacles contract and stretch

3. primitive organs

Phylum Cnidaria
i.e. Hydra sp.

Flatworms
1-15+ mm

1. flattened
2. eye spots

3. move in gliding motion

Phylum Platyhelminthes
Class Turbellaria

i.e. Planaria sp.

Roundworms
.2-10 mm

1. moves in rapid s form
2. round body
3. bilateral

4. anterior, posterior openings
Phylum Nematodes

Oligochaetes
1.5 mm - >2 cm

1. segmented
2. worm motion
3. hair bundles (setae)

Phylum Annelida
Class Oligochaeta

Leeches
> 1 cm

1. predatory or parasitic
2. terminal suckers

3. hermaphroditic

Phylum Annelida
Class Hirudinea

Gastrotricha
.1-1.5mm

1. mainly benthic
2. head bristles

3. eat algae, bacteria, protozoa

Phylum Gastrotricha
Order Chaetonotida

Tardigrades
Little water bears
< 1 mm

1. head and 4 trunk segments
2. 4 pair legs
3. eyes

4. herbivores
Phylum Tardigrada

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