: Likely Blue-Green Algae ( Cyanobacteria ). They contain phycocyanin. Note: Some like Nostoc form firm, jelly-like "freshwater grapes" attached to rocks.
Color provides a major clue about the pigments the algae uses for photosynthesis: Easy identification of freshwater algae
: Often Diatoms . They contain fucoxanthin and have silica in their cell walls, making them look like tiny shards of glass under a microscope. 3. Use Quick Field Tests : Likely Blue-Green Algae ( Cyanobacteria )
If you are observing algae in person, these simple characteristics can narrow it down: Color provides a major clue about the pigments
: Fresh blooms often smell like freshly mowed grass; older, decaying blooms may smell like rotting garbage.
: For student projects, a dichotomous key helps identify algae by asking a series of "yes or no" questions about its features. Algae Corner: How to Identify Different Algae Types
: These are large and "plant-like" but lack true roots and leaves.