1. fresh: The heart stops beating, so there is less oxygen inside the body. Cells begin to die, and the body no longer maintains a stable temperature. With no immune system regulating microbes that live inside the body, their populations start to shift and grow. Flies lay eggs, which will develop into maggots, in the cadaver's orifices (such as the mouth and nostrils).
5. dry remains: Only dried bones, cartilage, and skin remain. Surrounding plant life begins to surge due to the cadaver's nutrients, which may influence the ecosystem for years to come.
4. Advanced decay: Eventually, most of the cadaver's mass is transferred into the ground or consumed by scavengers. Fungi flourish. Decomposition gradually slows as maggots and scavengers leave. Plants close to the cadaver may die from the overload of nutrients and other components coming from the cadaver.
3. Active decay: The cadaver breaks open. Fluid spills out of the body's openings, releasing an abundance of nutrients, such as nitrogen and phosphorus, into the soil. Breaks in the skin allow more microbes, insects, and scavengers to enter the body.
2. Bloat: With less oxygen inside the cadaver, anaerobic bacteria flourish. These bacteria break down the body's carbohydrates, fats, and proteins, producing byproducts such as the gases hydrogen sulfide, methane, and ammonia. The accumulation of these gases gives the cadaver a strong odor and causes it to bloat. Maggots start to feed on the cadaver's tissues.