Carbon is one of the chemicals which all organisms living on the planet earth need for survival. Carbon is constantly circulating in many different forms through the atmosphere, living things, and the soil. A description of the carbon cycle that occurs naturally on our planet and within the troposphere could begin with the carbon dioxide that is present in air or dissolved in water. Through the process of photosynthesis, carbon dioxide is transformed into the vast number of compounds which combine in various ways to make up the substance of organisms. These organic compounds are passed from producers to the consumers. Whenever the producer or the consumer remove energy from organic compounds, carbon dioxide may be released again, either into the air, or into the water depending upon where the organism lives. However, as long as any unusable energy remains, organic compounds also remain.
Both producers and consumers discard their carbon-bearing wastes and at some point in their life die, leaving their remains on earth in the form of carbon compounds. The saprovores complete the process of releasing the carbon (in the form of carbon dioxide) from such wastes and dead bodies. Most of these final consumers, the saprovores, are microorganisms though some, such as the toadstool, are visible to the naked eye.
The process carried on by the saprovores is extremely slow. Over millions of years large masses or carbon compounds may accumulate in the earth as peat, coal, and petroleum. Some organisms also sidetrack carbon into shells that are deposited as rock. However, the main pathway in the carbon cycle is from the earth’s atmosphere or waters into living things and the process starts all over again.