|MadSci Network: Zoology|
You have asked a very interesting question. First, letís talk about cyanobacteria, then letís talk about what eats them.
Cyanobacteria, formerly known as blue-green algae, are primitive organisms of the kingdom Monera. They are prokaryotes, lacking a defined nucleus and other organelles with a double membrane. All cyanobacteria do, however, have cell membrane specializations that allow them to photosynthesize, or produce nutrients from sunlight. Although they were originally called blue- green algae because of their superficial resemblance to algae, cyanobacteria can range in color from blue to green to red to brown. Some cyanobacteria also fix nitrogen, which is a critical function for the entire food web. Although the atmosphere is about 80% nitrogen, this gaseous form of nitrogen (N2) is unusable by most organisms. Cyanobacteria can convert the N2 nitrogen gas to ammonia, which is then usable by other organisms. This nitrogen is critical for the growth of many plants and is one of the components of fertilizer. Cyanobacteria can grow as single cells or colonies, forming filaments, balls or even sheets. There are many, many species of cyanobacteria existing in the world today.
But your real question was: Who eats cyanobacteria? This question is not all that easy to answer, just as the question: Who eats mammals? Would be difficult to answer. I can give you some answers, however. Many cyanobacteria are symbionts, living in harmony with another organism. Cyanobacteria have formed mutally beneficial alliances with mosses, lichens, marine sponges, echiruid worms and ferns. The fern Azolla is cultivated with rice to nitrify the soil, because Azolla carries the cyanobacterium Anabena in its leaves. I am not sure you would consider symbiosis "eating," however.
So what does eat cyanobacteria? Well, humans do. Many sport drinks or health drinks contain Spirulina which is a high-protein cyanobacteria Ė it has even been touted as the "perfect food." Not all cyanobacteria are edible by humans or other mammals, however. Cyanobacteria are also responsible for "toxic blooms" in stagnant pond water. Ingesting this water can cause convulsions, uncoordinated movement (ataxia), bloody diarrhea and even death, so donít taste cyanobacteria without some guidance! Another unpleasant cyanobacteria is Lyngbya, which is responsible for swimmerís itch.
I hope that this helps answer your question.
For more information about cyanobacteria and some nice pictures, visit: Life History of Cyanobacteria The Cyanobacteria The Cryptobiotic crust Cyanobacteria
Ingrid Dodge, Mad Scientist
Try the links in the MadSci Library for more information on Zoology.