Blue-Green Algae

Abstract

Blue-green algae, or Cyanophyta (cyan = blue; phyton = plant), are found in a wide variety of environments. They occur in marine and fresh water, on and in soil, and on wet stones, cement, and plant pots. Some can withstand the temperatures of hot springs, others the cold of arctic pools. Still others are normal inhabitants of the alimentary canal of some animals, and another is an intracellular symbiont of an unicellular, flagellated, and otherwise colorless organism. Certain blue-green algae such as Anabaena are able to utilize elemental nitrogen from the atmosphere to build their proteins, thereby contributing to the nitrogenous content of soil. This process of nitrogen fixation, which is similar to that found in some bacteria, is important for maintaining soil fertility, for instance, in rice paddies.