Difference Between Nostoc and Anabaena (With Table)

Nostoc is a genus of blue-green algae or cyanobacteria which are found in ponds, lakes, damp rocks, or other damp places. Nostoc forms its colonies in a gelatinous sheath. The colonies are formed with filaments of moniliform cells. Within the gelatinous sheath, there are many tangled filaments composed of cells. Along the tangled filaments there are heterocysts.

Anabaena is a genus of filamentous blue-green algae or cyanobacteria. They are known for their amorphous filaments and intercalary heterocysts. Anabaena has the ability to fix nitrogen from the atmosphere. Anabaena builds endosymbiotic relationships with some plants like mosquito fern. Some of the Anabaena live within a plant as chloroplasts using which plants make their foods.

Comparison Table Between Nostoc and Anabaena

What is Nostoc?

Nostoc is a genus of blue-green algae characterized by the formation of ovoid, spherical, or cylindrical colonies. The filaments of these colonies of nostoc are situated in a gelatinous sheath. Nostoc is found in damp habitats and water bodies like lakes, ponds, damp rocks, or other damp places. The reproduction system of nostoc is either by fragmentation or simply by fission.

According to fossils, nostoc is one of the oldest organisms on the Earth, having lived for more than 3.5 billion years. There are two hundred different species of nostoc which has colonies in various environments including some of the world’s inhospitable regions. The reproduction system of Anabaena is either by akinetes or by trichome fragmentation. 

There are both freshwater and saltwater species of nostoc. Nostoc has a protective layer that allows them to live in any environmental conditions like a flood, drought, or an extremely low temperature. Some of the nostoc species are capable to withstand the thawing cycle and freezing, which helps them to survive in the Antarctic and Arctic.

Nostoc forms symbiotic relationships with some plant tissues like Gunnera, hornworts, and so on. Nostoc has the terminally-differentiated heterocysts which involve in the nitrogen-fixation. For undergoing photosynthesis nostoc contains pigments in the cytoplasm.

In Asia nostoc is consumed as a foodstuff due to the containment of Vitamin C and proteins. The common names for nostoc are witch’s jelly, witch’s butter, troll’s butter, and star jelly.

What is Anabaena?

Anabaena is a genus of blue-green algae or cyanobacteria which has the ability of nitrogen-fixing. Anabaena has beadlike filaments in the cells and gives a fishy odor. Anabaena produces akinetes which are thick-walled, dormant, enveloped, non-motile cells.

Anabaena formed its colonies composed of barrellike or bead-like cells. It is a filamentous blue-green algae and exists as plankton. The cells of Anabaena are not covered with a mucilaginous sheath. The trichomes or vegetative cells of Anabaena are generally arranged in chains that are not in a branched formation.

Anabaena forms an endosymbiotic relationship with some plants like rice plants, legumes mosquito fern. In these plants, they produce neurotoxins that are harmful to wildlife. Anabaena also protects plants from the pressure of gazing. Anabaena is a photosynthetic organism that has the ability of nitrogen-fixation. 

Anabaena is found in an endosymbiotic relationship with specific plants. Azolla is one of the common water ferns. By associating with the plant Anabaena supplies nitrogen to the plant while plants provide carbon for Anabaena. Farmers use Azolla as organic fertilizerfor harvesting rice as Azolla supply nitrogen in the soil. Anabaena is a photoautotrophic blue-green algae. It produces its own food by photosynthesis and during the process of photosynthesis, it generates oxygen in the air. It can be found in freshwater. It has a fishy odor and taste. It is known for producing neurotoxins.

Main Differences Between Nostoc and Anabaena

1. Nostoc refers to a genus of blue-green algae or cyanobacteria which form its colonies in a gelatinous sheath. On the other hand, Anabaena is a genus of filamentous blue-green algae or cyanobacteria which have beadlike filaments in the cells and gives a fishy odor.
2. Nostoc is free-living in damp habitats and water bodies like lakes, ponds, damp rocks. While Anabaenas builds endosymbiotic relationships with specific plants like mosquito fern.
3. Nostoc exists on the surface of the water, soil, and damp areas. Anabaena exists within one meter of the depth in the aquatic habitats.
4. Nostoc builds its colonies in a gelatinous sheath, appearing spherical, ovoid, or cylindrical. On the contrary, Anabaena builds filaments that are either coiled or straight.
5. The reproduction system of nostoc is either by fragmentation or simply by fission. The reproduction system of Anabaena is either by akinetes or by trichome fragmentation.

Conclusion

Nostoc and Anabaena are two blue-green algae or cyanobacteria that have the ability of nitrogen-fixing and photosynthesis. Both form symbiotic relationships with certain plants. Both possess akinetes and heterocysts. Both have bead-like vegetative cells. Cells of these cyanobacteria are arranged in a chain structure. But there are several differences between these two cyanobacteria or blue-green algae.

The main difference between nostoc and Anabaena is that Nostoc refers to a genus of blue-green algae or cyanobacteria which form its colonies in a gelatinous sheath. On the other hand, Anabaena is a genus of filamentous blue-green algae or cyanobacteria which have beadlike filaments in the cells and gives a fishy odour.

References

1. https://link.springer.com/chapter/10.1007/0-306-46855-7_17
2. https://www.sciencedirect.com/science/article/abs/pii/S1369527403001401