Blue-green, grey, whitish or reddish - no organelles
5. Please select from the following characteristics
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Filaments are short, usually attached to larger algae; chloroplasts and other organelles not found; cell contents blue-green or paler; exospores produced from tip
Chamaesiphon -
Material is whitish brown, like dirty cotton wool; filaments too thin for cell walls to be distinguished.
Sphaerotilus -
Red-brown, filaments too thin to distinguish cell walls.
Iron bacteria (eg Leptothrix) -
Filaments composed of regular cells occasionally interrupted by specialised cells (heterocytes or akinetes) with thickened walls, that are often larger ; chloroplasts and other organelles inside cells are not found (although granules may exist)
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Filaments are worm-like and may be motile by gliding, often with a tapered tip; chloroplasts and other organelles inside cells are not found (although granules may exist)
