<P> Decomposition is the process by which organic substances are broken down into simpler organic matter . The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere . Bodies of living organisms begin to decompose shortly after death . Animals, such as worms, also help decompose the organic materials . Organisms that do this are known as decomposers . Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition . The science which studies decomposition is generally referred to as taphonomy from the Greek word taphos, meaning tomb . </P> <P> One can differentiate abiotic from biotic decomposition (biodegradation). The former means "degradation of a substance by chemical or physical processes, e.g., hydrolysis . The latter means "the metabolic breakdown of materials into simpler components by living organisms", typically by microorganisms . </P> <P> Decomposition begins at the moment of death, caused by two factors: 1 .) autolysis, the breaking down of tissues by the body's own internal chemicals and enzymes, and 2 .) putrefaction, the breakdown of tissues by bacteria . These processes release compounds such as cadaverine and putrescine, that are the chief source of the unmistakably putrid odor of decaying animal tissue . </P> <P> Prime decomposers are bacteria or fungi, though larger scavengers also play an important role in decomposition if the body is accessible to insects, mites and other animals . The most important arthropods that are involved in the process include carrion beetles, mites, the flesh - flies (Sarcophagidae) and blow - flies (Calliphoridae), such as the green - bottle fly seen in the summer . In North America, the most important non-insect animals that are typically involved in the process include mammal and bird scavengers, such as coyotes, dogs, wolves, foxes, rats, crows and vultures . Some of these scavengers also remove and scatter bones, which they ingest at a later time . Aquatic and marine environments have break - down agents that include bacteria, fish, crustaceans, fly larvae and other carrion scavengers . </P>

When does a dead dog start to decompose