Difference Between Cyanobacteria and Algae

Cyanobacteria vs Algae

Algae, plants, and cyanobacteria are categorized as photoautotrophs because they produce their own food by photosynthesis.


They are also called blue-green bacteria. They are good examples of photoautotrophic bacteria. Photoautotrophs carry out photosynthesis. They use carbon dioxide as the source of carbon. Photosynthesis was first evolved in bacteria. It is highly probable that it first evolved in cyanobacteria. Blue green bacteria can be found in the surface layers of sea water as well as in the surface layers of fresh water. They can be also found as gelatinous growths on shaded soil, rocks, mud, wood and even on some living organisms. Most of the cyanobacteria are unicellular forms. But some get together to form filaments which are enclosed by mucous. Two good examples for this situation are Anabaena and Spirulina. Cyanobacteria are different from most other bacteria. More or less they resemble plants and algae as they can produce oxygen from water during photosynthesis. Photosynthetic pigments can be found on photosynthetic membranes. Photosynthetic membranes run throughout the cytoplasm. One of the photosynthetic pigments found in cyanobacteria is chlorophyll a. In addition, they contain phycocyanin, which is a blue-green pigment. Cells of blue-green bacteria are more often larger than those of other bacteria. Some cyanobacteria can fix nitrogen where nitrogen gas in air is converted to ammonia, which is in turn used in amino acid synthesis. This is done by a set of special cells known as heterocysts during nitrogen deficiency.


Algae are among the simplest plants found in the aquatic environment, and resemble higher plants by the presence of chlorophyll and being autotrophic. The very primitive algae were unicellular, but with evolution, they developed into multicellular forms, which had vertical and horizontal systems. Even now algae is found in association with damp soil and aquatic environments, both fresh water and marine. There are different groups of algae. In past classification systems, algae included 6 groups. Those are chlorophytes including green algae, euglenophytes, pyrrophyts, chrysophytes, phaeophytes including brown algae and rhodophytes including red algae. Algae as a group of plants show a wide variation in morphology. They are not only microscopic but also macroscopic. Their plant body could be unicellular, uninucleate, or unicellular multi nucleate or multi cellular multi nucleate forms. Almost all of the multicellular forms show an undifferentiated body, which is referred to a thallus. The shape of the plant body could be filamentous, thalloid, globe like, flattened or heterotrichous forms. Some are motile, and some are not motile. Some are attached to a substrate with the help of a holdfast. Algae show different colors because they contain different combinations of pigments. Unicellular forms show greater variation in their size and shape of chloroplast. Colony forms of algae are common in fresh water bodies. These are aggregations of cells having fixed number of cells. Reproduction in algae is complex because they show vegetative reproduction as well as sexual reproduction.


What is the difference between Cyanobacteria and Algae?

• Cyanobacteria are prokaryotes and algae are eukaryotes. They differ from each other fundamentally.


  • JoeCushing

    “What is the difference between Cyanobacteria and Algae?

    • Cyanobacteria are prokaryotes and algae are eukaryotes. They differ from each other fundamentally.”

    That statement, though it gives terminology provides no information about how the two are different.