Coprophagia comes from the Greek words copros (feces) and phagein (eat). Animals that participate in this activity include rabbits and most rodents. Why, you ask, would any animal consume its feces? Well, let’s take a step back for a minute. As an herbivore, getting the right amount of nutrients isn’t very easy. First you have to chew through fibrous plant matter, which can be laced with silica, an element that impedes digestion and increases plant toughness, then you have to deal with plant defenses, such as protease inhibitors that prevent the enzymes in your stomach from doing their job, and then you can attempt to extract the tiny proportion of a plant that is actually nutritious. It’s no wonder why most herbivores spend nearly all day grazing.
Again, though, why the poo-eating? To deal with all this tough plant matter, herbivores have a special kind of digestive system that super processes anything that comes through. I’m sure you’re familiar with the four stomachs that cows use to digest their food (foregut fermentation), but there is another specialized digestive system called hindgut fermentation that does not digest plant matter as efficiently. Many of these animals must consume their own scat in order to regain some amino acids and B-vitamins that they otherwise would lose (Hume 1989). Bacteria in the distal end of the digestive tract, i.e. the cecum, are able to break down certain molecules that cannot be broken down earlier in the digestive process. Rabbits and other herbivores produce a softer form of feces, termed caecotrophes, which contain these now-accessible compounds that can be absorbed through a second round of digestion. However, increased nutrition is not the only reason to consume feces: one species of salamander has been known to sample a potential mate’s excrement to determine if their diet composition is optimal (Curtis 2002).
Animals do lots of strange things, but there is usually a legitimate reason behind their actions. If something wasn’t advantageous or at least neutral to the survival of an individual, that habit would not survive the process of evolution. Therefore, if your pet rabbit is eating his feces, you should probably leave him be, or you may just be shaving a year or two off his life. But, hey, let’s keep coprophagy outside of the human world. No more “two girls, one cup,” okay?
Curtis, S. 2002. Wild Romance: Birds do it, bees do it, even educated fleas do it… Montana Outdoors, May-June Issue.
Hume, ID. 1989. Optimal digestive strategies in mammalian herbivores. Physiological Zoology 62(6): 1145-1163.
