When a body enters water, the decomposition process differs significantly from that on land. The aquatic environment introduces unique variables that influence how a body changes after death, affecting both the rate and the visible manifestations of decay.
Immediate Physical Changes
Upon immersion in water, a body rapidly loses heat through a process called algor mortis. Water conducts heat away from the body much faster than air, causing the internal temperature to drop quickly to match the surrounding water temperature.
Rigor mortis, the stiffening of muscles after death, still occurs in water, but its onset and duration can be altered; cold water can delay its appearance or make it less pronounced. The body’s tissues also begin to absorb water, leading to a phenomenon known as “washer woman” hands and feet, where the skin becomes wrinkled and can eventually slough off.
The Decomposition Process
Decomposition in water involves the breakdown of tissues by bacteria, but it proceeds differently than on land due to the reduced oxygen environment. Anaerobic bacteria become the primary agents of decay, producing gases like methane, ammonia, and carbon dioxide. These gases accumulate within the body, causing it to bloat and expand significantly, particularly in the torso and limbs.
A significant change in aquatic decomposition is the formation of adipocere, also known as “grave wax” or “corpse wax”. This waxy, grayish-white substance forms through a process called saponification, where body fats are chemically altered into insoluble fatty acids. Adipocere develops in moist, anaerobic conditions, such as those found in submerged bodies, and can preserve the body’s form and features for many years. While warmth can accelerate its initial formation, adipocere can still form in cold water, acting as a protective barrier against further decay.
Influencing Factors
Numerous environmental factors dictate the speed and nature of decomposition in water. Water temperature is a primary driver; colder water significantly slows bacterial activity and metabolic processes, slowing decomposition. Conversely, warmer water accelerates decay, as it promotes microbial growth and activity. For instance, decomposition in cold water can be equivalent to half the rate of decomposition on land.
Depth and oxygen levels also play a role; deeper water typically has colder temperatures and lower oxygen, creating anaerobic conditions that slow decomposition and favor adipocere formation. Salinity also impacts decay, with bodies in saltwater decomposing slower than those in freshwater, partly due to bacterial inhibition and osmotic effects. Water currents can physically abrade the body and transport it, while the presence of aquatic scavengers like fish, crabs, or turtles can accelerate tissue loss.
Buoyancy and Movement
The physical dynamics of a body in water are governed by changes in its density and gas production. Initially, a body will sink because its density is slightly greater than water, particularly if the lungs are filled with water. As putrefaction progresses, the anaerobic bacteria generate gases within the body cavities, primarily in the abdomen.
The accumulation of these gases increases the body’s overall volume without a significant increase in mass, thereby decreasing its density. This reduction in density eventually causes the body to become buoyant and float to the surface. Once the gases escape, either through natural orifices or tissue rupture, the body’s density increases again, causing it to re-submerge. Water currents can then transport the submerged or floating body over considerable distances from the original point of entry.