Blue-Green Algae Facts

Scientists previously believed that blue-green algae was eukaryotic and belonged to the algae family. However, scientists now know that blue-green algae is in fact prokaryotic. Blue-green algae is actually a type of bacteria that shares some of the same characteristics as plants. As a result, blue-green algae is also known as cyanobacteria. Despite its name, blue-green algae can also be red, yellow or brown in color.

Characteristics

• Blue-green algae exist all over the world and inhabit a variety of environments. They are commonly found in moist environments such as lakes, ponds and moist soil. However, they also occupy rocks, animal fur and the bark of trees. Blue-green algae reproduce using several methods, including budding, fragmentation and binary fission. In the budding process, blue-green algae form smaller cells from larger ones. In fragmentation, blue-green algae break into fragments that form separate organisms. The binary fission process involves dividing in half and duplicating DNA.

Types

• There are several different species of blue-green algae. Blue-green algae can exist as single-celled organisms, live in colonies or form filaments. Some species of blue-green algae are toxic, while others are harmless. One harmless species of blue-green algae is Spirulina. Spirulina is believed to have health benefits and is consumed by many cultures as a health food. Toxic species of blue-green algae include Anabaena, Microcystis, Oscillatoria and Aphanizomenon.

Abilities

• Like plants, blue-green algae contain chlorophyll and are photosynthetic. They use sunlight to release oxygen and to create carbohydrates out of carbon dioxide and water. Some species of blue-green algae called heterocysts are capable of nitrogen fixation. These species have a nitrogenase enzyme that enables them to take gaseous nitrogen from the atmosphere or water and convert it into ammonium. In contrast to bacteria that often use flagella for mobility, many species of cyanobacteria can move using gliding motility, which does not require flagella.

History

• Blue-green algae are ancient organisms. Billions of years ago, blue-green algae were responsible for converting the early earth's carbon-dioxide-rich atmosphere into an oxygen-rich atmosphere. Blue-green algae played a vital role in creating the environment that helped life to flourish on this planet. Over 3 billion years ago, clumps of blue-green algae formed large masses called stromatolites. Scientists in 2009 have discovered these ancient blue-green algae fossils in shallow, tropical waters such as those of Western Australia.

Warning

• Occasionally, blue-green algae will congregate in a dense mass on the surface of a body of water. This is known as a bloom. Blooms usually occur during the summer but may also form during the winter. Although blooms only last for one or two weeks, they can occur continuously for several months at a time. Some blooms are toxic. One sign that a bloom may be toxic is the presence of dead fish or animals in or near the water. Toxic blooms can cause adverse health effects in humans including skin rashes, hives and itchy eyes.