Aphanizomenon flos-aquae is a type of cyano-bacteria that biologically is quite similar to spirulina. It’s actually toxic in most places where it’s grown, but Klamath Lake is remarkably pure and free of toxins, and so the blue-green algae there can be ingested by humans and animals. And it grows there in heaps and tons. 100,000 kilograms of blue-green algae is harvested from the lake every year for the supplement industry. During the summer the growth of algae is so robust that the lake turns green and most of the native fish die out because the algae sucks out all the oxygen from the water.

The blue-green algae are often referred to as Cyanobacteria or Cyanophyta which is a phylum of Bacteria that obtain their energy through photosynthesis.The name "cyanobacteria" comes from the colour of the bacteria, cyan (blue); the bacteria do not use or produce cyanide. Putative fossil traces of cyanobacteria have been found from around 3.8 billion years which surely proves that Blue-green algae are among the most primitive life forms on Earth. Blue-green algae are present in almost all aquatic ecosystems, including creeks, rivers, lakes and wetlands. Individual cells are quite small, so blue green algae can be present in a water body without being visible. However, as environmental conditions become just right, algae numbers can start to increase rapidly and blooms, or scums, become easily visible across the water surface. The blooms range in color from dark green to yellowish–brown and develop paint like consistency as they dry out around the water’s edge. A blue pigment may also be seen as they dry.They are in fact prokaryotes, not algae.They share abilities of plants, as they can perform photosynthesis. Also, they have some features of primitive bacteria, which lacked the plant cell wall. Interestingly, they also share characteristics of the animal kingdom as they contain (on their cellular membrane) complex sugars which are quite similar to glycogen. Among blue-green algae we find both edible and toxic species, adaptive to the most extreme habitats on Earth, including deep-seas, hot springs, and Antarctic ice. Edible species have been used by humans as food for thousands of years. Habitats with sufficient algae growth include the Pacific Ocean near Japan and Hawaii, and large freshwater lakes in Africa, North and South America and in Mexico.