Decomposition and the subsequent recycling of nutrients is a finely orchestrated process involving many participants. A dead body, left to decompose, constitutes a unique and complex ecosystem that beckons and supports different creatures at different times.
Like many transformative experiences, the process occurs from the inside out. From the outside, a newly dead body looks relatively unchanged. Inside, however, a multitude of new intentions and activities has begun. For instance, millions of microorganisms that live in the intestines switch activities. Those that before death fed on the contents of the intestine now begin to digest the intestine itself and then the surrounding internal organs. The pancreas, packed with digestive enzymes, rapidly digests itself. In similar fashion the enzymes inside individual cells are released from their habitual work when the cell dies and turn to breaking down their former homes, then breaking down the cellular neighborhood. With an enthusiastic frenzy, the enzymes and other chemicals released by the dead cells join other organisms, including bacteria called clostridia and coliforms, and together they infiltrate other parts of the body.
Much of the effusive decomposing process at this point still remains hidden from the observer. Blowflies and houseflies, attracted at the moment of death, are usually the first external visitors to be seen on a dead body. Unhampered by the normal defenses of the living animal, they rapidly lay eggs around wounds and natural body openings, including the mouth, nose, eyes and anus. Typically within twenty-four hours the eggs hatch, and maggots move into the body to feed on flesh, fluids and blood.
The young maggots move en masse throughout the body. Sticking together, they keep each other warm and share digestive secretions. Working in proximity is more efficacious than working alone. The living, wiggling creatures visible in the orifices of the dead animal—a sight often disconcerting to those unaccustomed to observing the dead—spread bacteria, secrete digestive enzymes and tear tissues apart with their tiny mouth hooks.
As released fluids fill the body cavities, gases, including hydrogen sulfide, methane, cadaverine and putrescine, are produced as byproducts of anaerobic cell activity. The stench of a dead body when such gases are released often repels people. To corpse-loving creatures, however, these smells are delicious and heady, an invitation to an awaiting feast.
As decomposition continues unabated, the smells and oozing body fluids attract more blowflies, flesh flies, beetles and mites. Predator flies and beetles join in at this stage to feed on maggots as well as on the decaying flesh. Parasitoid wasps fly in to lay eggs inside maggots.
Eventually the bloated body collapses like a deflated balloon. Body fluids drain out of every orifice and seep into the surrounding soil, where they feed other insects and mites. Some fully grown maggots leave the body and bury themselves in the soil, where as pupae their astonishing transformation into luminous winged beings begins in earnest.
With the soft food almost gone, the remaining maggots look elsewhere for their food while predatory beetles, which have strong chewing mouth parts, take over. These beetles feed on skin and ligaments and lay eggs. The beetle larvae hatch and also feed on the corpse.
As the body continues to dry out, butyric acid generates a cheesy smell that attracts new guests to the corpse, such as the cheese fly, which consumes any morsel of remaining flesh. Animals that can feed on hair, including tineid moths and certain bacteria, appear for their part of the meal and stay as long as traces of hair remain. Mites, in turn, feed on the hair-eating organisms. Eventually all the hair disappears, and only the skeleton and the teeth remain to bear witness to what was once a living, breathing animal.
Decomposition is complete, orchestrated with a precision and attention to detail and timing far beyond what we humans could have engineered. The animal metamorphoses into myriad new forms, and the cycle of life and death continues.