Flagellated forms

Group

Dinoflagellates

brown, 2 flagellae (1 in girdle),
free-swimming,
tough armour (<0.4 mm)

Peridinium
(Star of the Marshes)

Green Algae
(Chlorophyta)

spherical colonies,
cells with 2 flagellae,
(Volvox: 0.5-2 mm)

Volvox
(Jewel of the Pond)

Not all green algae are green.

tiny, green / red, often in
bird baths, (<0.05 mm)

Haematococcus Chlamydomonas

Non - flagellated forms

Group

Blue-green algae
(cyanobacteria)

blue-green, often slow locomotion,
used to be considered algae but more
closely related to bacteria
(cells <0.05 mm, colonies can be many mm).
The bigger cells are able to fixate nitrogen.

Anabaena

Diatoms

usually brownish, silica cell wall
in 2 parts, solitary or
colonial, some have a slow gliding
motion. (<0.5 mm)

Asterionella

Desmids
(Gamophyta)
conjugating
green algae

green, no flagella, mainly
solitary, some colonial, various shapes,
2 semi-cells which are mirror images
(<0.5 mm)

Green algae
(Chlorophyta)

green, don't move, no flagella,
not attached to a surface.
Star-shaped colony:
Pediastrum (<0.3 mm)

Pediastrum
(Star of the Pond)

bottom right: Scenedesmus
<0.03 mm

Chlorella (symbiont
in several organisms)

Other algae of various growth forms

Group

Water net

a sock-like colony, green algae
(related to Pediastrum)

Hydrodictyon
(The Water Net)

Filamentous forms

Pond scum
(Gamophyta:
conjugated
green algae)

non-branching, green chains
of cells with distinctly
shaped cell contents.
(cells <0.1 mm, chain - cms)

Spirogyra
(helical chloroplast)

Other non-
branching forms

several non-related groups

Ulothrix

Branching forms

mostly green algae

Cladophora

Red algae
(Rhodophyta)

Mainly marine, but some
freshwater forms,
not always red.

Porphyridium