What is a characteristic feature of cyanobacteria?

Cyanobacteria are unique microorganisms that are often referred to as blue-green algae, although they are not true algae. A defining characteristic of cyanobacteria is that they contain chlorophyll A, which is essential for photosynthesis, enabling them to convert light energy into chemical energy. In addition to chlorophyll A, they possess accessory pigments, such as phycocyanin and phycoerythrin, which give them their distinctive blue or green coloration. This photosynthetic capability allows cyanobacteria to produce oxygen as a byproduct of their metabolic processes, a trait that has significant ecological implications.

The presence of chlorophyll A is crucial because it allows cyanobacteria to perform oxygenic photosynthesis, differentiating them from other prokaryotic organisms that may engage in anaerobic processes or do not perform photosynthesis at all. Thus, the combination of chlorophyll A and the blue pigments is a hallmark feature of cyanobacteria, making them vital contributors to both aquatic ecosystems and the Earth's overall biosphere.