A single filament of Cyanobacteria. Cyanobacteria are photosynthetic prokaryotes in the kingdom Bacteria. Cyanobacteria possess internal, photosynthetic membranes called thylakoids which carry out photosynthesis.

Purple Bacteria

The slide that this phot was taken from was split into 3 sort of sections: heterotrophs on the right side, photosynthesizers in the middle (and right), and these purple bacteria on the left. Actually, I had spent so much time with the heterotrophs on the right that I never saw the massive colony of purple bacteria growing on the left. I assume that they are photosynthetic; maybe purple sulfurs, but I doubt it, because I don’t see where they would be getting their sulfur from.