What are blue-green algae classified as?

Blue-green algae are classified as cyanobacteria. This classification is due to their unique characteristics that distinguish them from true algae and other groups of organisms. Unlike protozoa and fungi, which are separate kingdoms with distinct features and functions, cyanobacteria are photosynthetic bacteria that can conduct photosynthesis similar to plants.

Cyanobacteria have chlorophyll a and can produce oxygen as a byproduct of photosynthesis, making them vital to aquatic ecosystems and contributing significantly to the Earth's oxygen supply. Although they are often referred to as blue-green algae due to their color and ability to photosynthesize, they are actually prokaryotic organisms, which means they lack a nucleus and other membrane-bound organelles that true algae possess.

True algae belong to the eukaryotic domain, while cyanobacteria are classified as prokaryotes. This classification helps clarify their role in the ecosystem and their differences in cellular structure and reproduction. Therefore, the correct classification of blue-green algae as cyanobacteria is crucial for understanding their biological characteristics and ecological importance.