Blue-green bacteria - Anabaena affinis
The genus Anabaena is filamentous and often looks like a string of beads. In the middle of the filament of Anabaena affinis you can observe a resting spore, which is bigger than the other cells. A resting spore can sink to the bottom and is able to survive unfavourable periods. They will germinate under favourable environmentally conditions and give start to a new filament. The spores arise by enlargement of a single cell or several cells fuse together to become a single cell.
The vegetative cells have a size about 4-8 my (1my=1/1000mm).
Anabaena affinis, together with other species of Anabaena, can be present in great numbers and form water bloom due to the gas vesicles in their cells