Algae ~ Some common freshwater types with links to Micscape resources

Algae are a very diverse group of organisms that vary widely in size, shape, colour and habit. Ten or so phyla are represented in freshwater. This page gives an overview of some commonly found freshwater algae. The algae have been grouped by their major features. Some of these are artificial groups (i.e. not necessarily related to their taxonomy) but are convenient ones for the pond dipper. More about the classification of algae and protozoa.

Group		Key features	Micscape links
Flagellated forms (some are also often classed as protozoa) note: These flagella are hardly visible, only with strong magnification.
Euglenoids		green, flagella (whip-like cilia), free-swimming, red eye spot, body is flexible <0.4 mm	Flagellated algae/protozoa - includes Euglenaa heart shaped euglenoid: Phacus
Dinoflagellates		brown, 2 flagella, (1 in girdle), free-swimming, tough armour <0.4 mm	Peridinium - Stars of the Marshes
Green algae (Chlorophyta)		spherical colonies, cells with 2 flagella Volvox: 0.5 - 2mm	Volvox - the jewel of the pond Volvox in 3D Some other smaller colonial flagellates: Gonium, Eudorina, Pandorina, Sorastrum (rare), Synura, Uroglena
not all green algae are green		tiny, green/red, often in bird baths <0.05 mm	Haematococcus Haematococcus - image another small flagellated green algae: Chlamydomonas
There are many other small flagellated algae of non related groups. Classification is difficult.
Non-flagellated forms
Blue-green algae (cyanobacteria)		blue-green, often slow locomotion, used to be considered algae but more related to bacteria cells<0.05 mm colonies can be many mm	Smallest page on the web - 'bacteria' - image of a cyanobacteria
Diatoms		usually brownish, silica cell wall in two parts, solitary or colonial, some have a slow gliding motion <0.5 mm	Smallest page on the web - 'diatoms' Those who live in glass houses' Diatoms on strings Bacillaria - 'Carpenter's rule' diatom Library search - type diatom for articles on f/water & marine species Test diatoms - species to test optics
Desmids (Gamophyta: conjugating green algae)		green, no flagella, mainly solitary, some colonial, various shapes, two semi-cells which are mirror images <0.5 mm	What are desmids? Smallest page on the web - desmids Bill Ells' page - extensive articles on various species and aspects of desmids Desmids in 3D Desmid gallery
Green algae (Chlorophyta)		green, don't move, no flagella, not attached to a surface starshaped colony: Pediastrum <0.3 mm bottom right: Scenedesmus <0.03 mm	Pediastrum - image only Pediastrum - the 'star' of the pond Asterococcus Some other common 'non flagellates': Chlorella (symbiont in several organisms), Scenedesmus, Dictyosphaerium
Other algae of various growth forms
Water net		a sock-like colony, green algae (related to Pediastrum) up to 20 centimeters	Hydrodictyon - the water net
Some other common algae of various types: Botrydium, Chaetophora, Coelochaete, Enteromorpha
Filamentous forms
Pond scum (Gamophyta: conjugating green algae)		non-branching, green, chains of cells with distinctly shaped cell contents cell with <0.1 mm. length: centimeters	Spirogyra - chloroplasts like helix Spirogyra in 3D Zygnema - starshaped chloroplasts Mougeotia has plate-like chloroplasts
Other non-branching forms		several non related groups	Oedogonium Some other common filamentous types: Tribonema, Ulothrix, Vaucheria
Branching forms		mostly green algae	Cladophora, Draparnaldia, Stigeoclonium
Red algae (Rhodophyta)		mainly marine, but some freshwater forms, not always red	Batrachospermum Porphyridium

Protozoa	First Page	Arthropods
Worms	Collecting tips	Insect stages

Some introductory books on freshwater algae:

From the Pictured Key Nature series: 'How to know the freshwater algae' by G.W. Prescott.
Wm. C. Brown Company Publishers, Dubuque, Iowa
in this series also avaliable: 'How to know the Protozoa' by Jahn, Bovee and Jahn

'A beginner's guide to freshwater algae' by H Belcher and E Swale. Institute of Terrestial Ecology, 1978.

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Note: This page with links hopefully gives a useful overview, but it's neither a formal identification guide nor comprehensive. Stoneworts for example, which are macroscopic algae looking like a higher plant, have not been included (but would welcome articles).

Many thanks to all the Micscape contributors whose articles this guide links to. For clarity their names are omitted in the links above. Articles and/or images on any of the groups without links (e.g. protozoa in black type) would be welcome.

Some of the artificial groups and key features have been adapted from those in 'Collins field guide to freshwater life' by R Fitter and R Manuel, 1986. Any mistakes are by the web page authors!

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