The hippopotamus, one of the world’s largest land mammals, is a vegetarian. The Common Hippopotamus (Hippopotamus amphibius) is classified as a herbivore, meaning its diet is plant-based. Despite their enormous size and aggressive demeanor, their biology is structured around consuming vegetation. This diet is why they spend their days submerged in water, as this semi-aquatic lifestyle conserves energy for nocturnal grazing.
Defining the Hippopotamus Diet
The diet of the hippopotamus consists almost entirely of grasses, making them specialized grazers. Their foraging activity begins at dusk, when they leave the water to travel inland to grassy plains, sometimes venturing up to five miles from their aquatic home in search of suitable pasture. This extensive nightly journey, lasting approximately five to six hours, is necessary to consume the required amount of forage.
An adult hippo typically consumes around 80 to 110 pounds of short, terrestrial grasses each night. This amount is relatively small considering their massive body weight, which is possible because their sedentary daytime behavior helps them maintain a low metabolic rate. Hippos eat very little aquatic vegetation; while they may occasionally consume fallen fruits, their survival hinges on the availability of land grasses.
Unique Anatomical Adaptations for Grazing
The physical structure of the hippopotamus is suited for its grazing lifestyle. Their wide, muscular lips are not designed for selective browsing but function like a natural lawnmower. They use these lips to grasp and tear large quantities of short grasses from the ground, often with a jerking motion of the head.
Once the grass is cropped, the food is passed back to their powerful molars, which are covered in complex enamel folds to effectively grind the plant material. The massive canine tusks and incisors, which can grow up to 20 inches long, are not used for eating. These imposing teeth serve primarily as weapons for fighting, defense, and dominance displays, especially among males.
Their digestive system is adapted to process fibrous grass efficiently. Hippos are classified as non-ruminating foregut fermenters, possessing a multi-chambered stomach (typically three compartments) where microbial fermentation of cellulose begins. This system allows them to break down the hard-to-digest plant matter and extract maximum nutrition. Their digestive process is slower than many other herbivores, a trait that accommodates their low food intake relative to their size.
Dietary Deviations and Misconceptions
While the hippopotamus is a herbivore, documented instances of them consuming meat often lead to confusion. These behaviors, such as scavenging on carrion or predation, are considered opportunistic anomalies rather than part of a regular diet. Meat consumption is often linked to periods of environmental stress, such as drought, or a need to supplement a mineral deficiency.
The hippo’s digestive system is not designed to process animal flesh efficiently, and consuming meat can lead to health issues. They are not classified as omnivores because their anatomy and physiology are optimized for a plant-based diet. These occasional deviations, including documented cases of cannibalism, represent survival tactics in challenging conditions, but the hippo remains fundamentally a grass-eating vegetarian.