The Hippopotamus (Hippopotamus amphibius) is one of Africa’s largest and most recognizable land mammals, spending its days submerged in rivers and lakes across sub-Saharan Africa. These massive semi-aquatic creatures often cause dietary confusion due to their formidable size and large, intimidating teeth. Despite popular misconceptions, the hippopotamus is scientifically classified as a herbivore, meaning its diet consists exclusively of plant matter. This classification is established by decades of observation of their natural feeding behavior in the wild.
The Hippo’s Official Herbivorous Diet
The primary diet of the common hippopotamus consists almost entirely of short grasses, making them specialized grazers rather than general browsers. They are nocturnal feeders, leaving the water at dusk to travel onto land, often moving several miles to reach preferred grazing areas known as “hippo lawns.” This nighttime routine allows them to avoid the intense African sun, which could dry out their sensitive skin, and helps them conserve energy by remaining inactive during the day.
An adult hippo consumes a surprisingly modest amount of food relative to its colossal body mass. On average, a hippo consumes between 65 to 110 pounds of grass each night. This quantity represents only about 1 to 1.5 percent of their total body weight, which is significantly less than what other large grazing mammals typically require. Their sedentary lifestyle, spending up to 16 hours a day resting in water, allows them to subsist on this low-intake, low-energy vegetation. They use their broad, muscular lips to pluck the grass, effectively mowing the vegetation down to the root.
Physical Evidence: Anatomy Supporting Grazing
The hippo’s anatomy strongly supports its classification as a herbivore, especially concerning its complex digestive system. Hippos are known as non-ruminant foregut fermenters, a digestive strategy distinct from true ruminants like cattle or deer. They possess a three-chambered stomach where microbial fermentation occurs, allowing them to efficiently break down the tough cellulose found in grass.
Unlike true ruminants, hippos do not regurgitate and re-chew their food as cud. Their system is optimized for a slow process, retaining food for extended periods to maximize nutrient extraction from the fibrous plant material. Their dentition is also specialized for this diet; the flat, powerful molars are perfectly suited for grinding down coarse grasses. The massive canine and incisor tusks, which can grow up to 20 inches long, are not used for eating, but are instead primarily used for defense, fighting, and social dominance displays.
Rare Instances of Meat Consumption
The question of whether hippos eat meat arises from documented, yet highly unusual, observations of carnivorous behavior in the wild. Hippos have occasionally been recorded scavenging on carrion, consuming the carcasses of dead animals such as impalas, wildebeests, and even other hippos. In rare instances, they have been seen preying on small animals or stealing kills from other predators, but this behavior is opportunistic and not reflective of their typical diet.
Scientists theorize that this anomalous meat-eating is linked to nutritional deficiencies or environmental stress, such as a lack of essential minerals or protein during periods of drought. When their primary food source is scarce, some hippos may turn to unconventional means to supplement their diet. The rarity and opportunistic nature of this behavior confirm that it is an adaptation to difficult circumstances, rather than an inherent part of their physiological diet. Despite these documented deviations, the hippo’s entire anatomy, from its specialized stomach to its grinding teeth, is designed for a plant-based diet, solidifying its identity as a herbivore.