Hippos are large, semi-aquatic mammals that spend a significant portion of their lives submerged in water. Their imposing size and aquatic habits often spark curiosity about their movement capabilities, both in and out of the water.
Aquatic Movement and Speed
Hippos do not truly “swim” in the traditional sense. Their dense bodies and short legs prevent them from floating or propelling themselves like other aquatic mammals. Instead, they move through water by walking, trotting, or galloping along the riverbed. They use their powerful legs to push off the bottom, even in deeper areas, creating the illusion of swimming.
Underwater, hippos can achieve high speeds. Adult hippos move at approximately 5 miles per hour (8 kilometers per hour) along the riverbed. Young hippos can reach speeds up to 8 miles per hour. This unique “underwater gallop” allows them to navigate their aquatic environment with agility despite their massive size. They can hold their breath for 3 to 5 minutes, which facilitates their underwater movements.
Unique Adaptations for Water
Hippos possess several physical adaptations for their semi-aquatic lifestyle. Their bones are incredibly dense, contributing to their high specific gravity, which allows them to sink and walk along riverbeds rather than float. Their eyes, ears, and nostrils are positioned high on their heads, enabling them to remain mostly submerged while still seeing, hearing, and breathing. Their nostrils and ears can close automatically underwater, and a clear membrane covers their eyes for protection while maintaining underwater vision.
Their skin is highly sensitive and prone to drying and sunburn. To counteract this, hippos secrete a reddish, oily substance, often called “blood sweat,” which acts as a natural sunscreen and antibacterial agent. Spending most of the day submerged helps them regulate body temperature and protects their skin from the harsh African sun.
Beyond the Water
While their aquatic movements are distinctive, hippos also exhibit speed and agility on land. Despite their bulky appearance and massive weight, they can run fast over short distances. Hippos can reach speeds of approximately 19 miles per hour (30 kilometers per hour) on flat ground. This speed is notable given their average weight, which can be up to 4 tons for males.
Their land movement is characterized by a unique trot, where they can achieve brief airborne periods. This burst of speed allows them to quickly move between water sources or escape threats. While they spend their days largely submerged, their nocturnal grazing habits often involve traveling several miles from water to find food, showcasing their terrestrial mobility.