Phylum Cyanobacteria

Cyanobacteria  are prokaryotes,  but  they are not  like bacteria  in  the usual  sense of  the word.  The cyanobacteria  lack chloroplasts,  and  their  light capturing pigment  is  scattered  over,  highly  folded inner membrane  lamellae. However,  their  photosynthetic mechanism differ from that of other bacteria. Like plants, they derive  their required electrons by breaking apart water molecules. The blue-greens have an  important  ability  to 'fix'  nitrogen,

1)  Unicellular or filamentous, some of  the filamentous  forms bear branches.

2)  Autotrophic, the  photosynthesis  is  carried  out on membranes  round  the  periphery of  the cells.

3)  Photosynthetic pigments include chlorophyll plus  red  pigment (phycoerythin)  and  blue pigmerlt (phycocyanin).  Some examples Chroococcus,  Arlabaena