Capybaras, the world’s largest rodents, are semi-aquatic animals found in South America, primarily consuming grasses and aquatic plants. A particular behavior often surprises observers: capybaras eating their own feces. This practice, though unusual to humans, is a normal and important part of their biology.
Explaining Coprophagy
The consumption of feces is known as coprophagy, derived from the Ancient Greek words “kópros” for feces and “phageîn” for to eat. This habit is a natural and beneficial strategy for many herbivorous animals, commonly observed in rodents and lagomorphs like rabbits and guinea pigs. Coprophagy is not an indication of illness; instead, it is a biological adaptation that allows them to extract more nutrients from their plant-based diets. This widespread occurrence highlights its role as an efficient biological process for nutrient acquisition.
Nutritional Benefits for Capybaras
Capybaras engage in coprophagy to re-ingest nutrients not fully absorbed during the first pass through their digestive system. Their diet, consisting mainly of grasses and aquatic plants, is high in fiber but challenging to fully digest on a single pass. Through this re-ingestion, capybaras gain a second opportunity to break down and absorb essential compounds. This includes nutrients like B vitamins, vitamin K, and proteins, which are often produced by microbes in their gut after the initial digestion. Maximizing nutrient extraction through coprophagy is important as their bodies have a limited ability to store fat, requiring a constant intake of nutrients.
How Their Digestive System Works
The capybara’s digestive system is specialized for its herbivorous diet, functioning as a hindgut fermenter. Unlike ruminants, which ferment food in the stomach, capybaras perform the bulk of their digestion in the large intestine and an enlarged cecum. This cecum serves as a chamber where bacterial populations thrive and break down tough plant material. Because this fermentation occurs after the main absorption sites in the small intestine, many nutrients produced by the microbes would otherwise be lost.
To overcome this, capybaras produce two distinct types of droppings. They excrete hard, oval-shaped feces that are true waste products, and softer, nutrient-rich pellets, often called cecotropes. These softer pellets, which may appear as a shapeless mass or a chain of fecal pellets, contain microbial protein and other compounds. Capybaras consume these softer pellets directly from the anus, allowing the nutrients to pass through the small intestine for absorption during this second digestive cycle. This process, known as cecotrophy, ensures that the capybara efficiently utilizes all available nutrients from its fibrous diet.