Planktonic Unicellular and Colonial algae

Phylum Chlorophyta
(page still under development)

colonial Chlorophyte: planktonic, sometimes bloom-forming. Colony is very dense, making cells hard to see; contains yellow oil droplets which can be squeezed out under a coverslip


This alga is characteristic of shallow water which dries out regularly, such as bird-baths, which it stains a blood-red colour.

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Haematococcus is a chlorophyte, though it doesn't look it at all, thanks to the haematochrome pigment. The spherical cells are actually cysts, which enable Haematococcus to survive desiccation.

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This is a vegetative cell: the cell wall is visible, and two flagella (arrowed) can be seen emerging; the vegetative cells are motile.

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Vegetative cells of Haematococcus
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This cell shows the protoplasmic extensions between the protoplast and the cell wall (just barely visible), which are characteristic of Haematococcus

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Eudorina is a colonial flagellate, related to Volvox. The colonies spin rapidly through the water. This one was found in a temporary 'pond' - a tyre-track in a barley field. The two flagella are just visible in some of the cells.
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Pandorina is similar to Eudorina but the cells are packed closely together and often angular as a result.
Paulschulzia tenera
Colonial Chlorophyte:cells or cell groups in clearly defined spherical mucilage envelope, with individual sheaths and flagellum extending beyond outer envelope
Cells united to form a circular flat plate. Outer cells frequently bear a pair of horns, and there may be gaps between cells
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Chlorella from a culture.
Formerly known as Selenastrum capricornutum, this unicellular green alga is Pseudokirchneriella subcapitata, widely used as a test organism in toxicity testing.
Spindle-shaped cells, either solitary or lying parallel in groups of 4 or 8. Some are ornamented with apical or medial spines: these have recently been placed in the genus Desmodesmus. This one is Scenedesmus dimorphus.



John Kinross