The common hippopotamus (Hippopotamus amphibius) is a massive, semi-aquatic mammal, recognized as the third-largest terrestrial animal after the elephant and white rhinoceros. Its barrel-shaped body rests on short, stout legs, and its skin is slate-gray or brownish-pink. These social herbivores gather in groups called pods, bloats, or schools, which can number from 10 up to 100 individuals. A single dominant male typically presides over the pod and its specific stretch of water.
The Critical Need for Aquatic Environments
The hippo requires a stable water source, spending up to 16 hours daily submerged in rivers, lakes, or swamps. This manages their body temperature and protects their sensitive skin. Hippos have a fine epidermis highly susceptible to dehydration and sun damage.
To combat the harsh African sun, hippos secrete a unique, reddish fluid from mucous glands. This secretion, often mistakenly called “blood sweat,” acts as a natural moisturizer and sunscreen. Since hippos cannot sweat effectively, the water provides external cooling, preventing overheating.
The placement of their eyes, ears, and nostrils high on the skull allows them to remain almost entirely submerged while breathing and observing their surroundings. Their dense bone structure means they do not swim; instead, they walk or push themselves along the bottom. They can hold their breath for up to five minutes, allowing them to rest and move underwater.
Grazing: The Hippo’s Terrestrial Activity
While water is their sanctuary during the day, hippos must venture onto land to feed, strongly associating them with grasslands. They are bulk grazers, and their diet consists almost entirely of short grasses. They use their wide, tough lips to grasp and tear the grass, consuming a relatively small amount of food for their body size, typically 35 to 40 kilograms per night.
Foraging is a nocturnal activity, beginning after dusk and ending before sunrise. This nighttime schedule is a behavioral adaptation that avoids daytime heat and dehydration. Hippos follow well-established paths leading from the water to their feeding grounds.
They often cover between 1 and 3 miles (3 to 5 kilometers) in a night to graze. In times of drought, they may travel up to 6 miles (10 kilometers) to find sufficient food. Unlike their social behavior in the water, grazing is usually a solitary activity, and they do not exhibit territorial behavior on land.
Defining the Hippo’s Natural Range
The common hippopotamus is distributed across Sub-Saharan Africa. Their geographical presence depends entirely on the coexistence of perennial water sources and accessible grazing land. Countries in Eastern and Southern Africa, such as Zambia and Tanzania, represent the strongholds for the species and hold the largest populations.
The total wild population is estimated to be between 115,000 and 130,000 individuals, and the species is currently classified as Vulnerable. Habitat loss, often due to human encroachment and agricultural development, remains the primary threat to their survival. Expanding human populations increase the conflict between people and hippos over land and water resources.