Many elementary school boys have a great interest in all aspects of the decomposition side of the food chain.
It is difficult to predict precisely how fast a guinea pig or any other animal will decompose.
Farmers, especially those who raise livestock, bury a lot of small animals over the years. They also prepare many animal carcasses or parts of them as study specimens.
And yet they still don’t always know what to expect when an animal starts to decompose.
There are a great many variables, different factors which change the time it takes for all the flesh and skin and fur to leave the bones.
My guess is that a guinea pig won’t completely decompose for at least six more months if it is buried pretty deeply and in a box, we’d expect the whole process to take a year or more.
This is based on what happens to gophers and rats, animals about the size of a guinea pig, when they are buried. The body will be worked on by a huge number of organisms whose job it is to return plant and animal tissue to the soil.
They are of all kinds and all sizes and, as a group, are known as decomposers.
Bacteria and fungi that live in the soil and within the body itself will work on the soft parts of the animal, eventually returning the elements to the earth to nourish plants and soil organisms. There are three obvious variables in this part of the cycle.
The first is that some soils have a lot more bacteria than others. Second, most of these microorganisms need oxygen. The deeper you go into the ground, the less oxygen there is in the soil.
Finally, most of the decomposer microorganisms like it warm and moist.
Most soil is probably only medium-warm at 30 inches down, probably something around 56°F or a little cooler would be my guess. If a guinea pig’s body is in a garden, it’s probably nicely moist, but if it’s in unwatered soil the decomposers’ work will be slowed down quite a lot, especially if the region hasn’t received enough rain to penetrate more than an inch or two this summer.
If we bury a gopher in summer in this area, not as deep and not in a box, it won’t have become just bones if we accidentally dig it up when working in my garden the following February, even though all the factors I list above are at a high level here.
That’s why we estimate that it would be at least another six more months before decomposition occurs fully.
Some larger soil invertebrates may be able to help the box disintegrate and also go to work on the body.
Some eat meat, and some, such as dermestid beetles, specialize in skin and hair. Vertebrate museums which prepare study specimens of skeletons actually keep colonies of these beetles, to finish cleaning the bones.
They are also found fairly frequently on livestock farms like ours, and in woodland where they help to clean up casualties.
And there are other invertebrate meat-eaters that live in the soil, such as ants and worms and beetles. There are more in the upper layers than at the depth where the animal is buried, but some may get down that far.
There are a few other points. Eventually, even the bones will disintegrate and feed the plants and the soil, although the guinea pig’s teeth will be around the longest, tooth enamel is a very durable material.
Also, the soil organisms often move bones around as they work on them. If you dug it up, I wouldn’t expect to see a perfect skeleton of guinea pig, all in one place, though you might be lucky if the animal has a box around it.
There is actually a center on the East Coast of the United States that is devoted solely to studying how animal and human carcasses decompose and then disintegrate. It seems that even scientists who specialize in old bones still don’t know as much about the process as they would like to.
The amount of time that it takes for an animal like a guinea pig, or even a human, to decompose to the point of becoming skeletonized is highly variable and depends on many factors.
Those factors include, but are not limited to, the season of the year, the ambient temperature, the amount of rainfall, the depth of burial, whether insects can reach the body, the pH of the soil, and whether the body was embalmed or not.
The size of the body also plays a part in determining how quickly decomposition occurs.
Additionally, if a body is enclosed in a coffin, or wrapped in plastic bags or carpet, for example, it will take longer to decompose because it is protected from the elements.
