The hippopotamus (Hippopotamus amphibius) is a massive African mammal that spends the majority of its day submerged in water, a lifestyle that sets it apart from many other large land animals. This semi-aquatic existence requires a unique biological design to manage body temperature, skin health, and movement. The adaptations of this species have long fascinated observers, leading to curiosity about how such a colossal creature maintains its identity as a mammal while living largely beneath the water’s surface. Examining the hippo’s physical traits reveals several specialized features that allow it to thrive in its watery habitat.
Yes, Hippos Have Nipples
The female hippopotamus possesses mammary glands and teats for feeding its young, a certainty shared across the class Mammalia. Unlike many terrestrial mammals whose teats are located on the chest or abdomen, the hippo’s are positioned in the inguinal region, near the hind legs. This specialized placement is a direct adaptation to its aquatic environment, ensuring the teats are accessible while the mother is partially or fully submerged. Female hippos typically have two milk-producing structures, corresponding to the single calf usually born after an eight-month gestation period.
The small number and location of the teats reflect a simplified approach compared to animals that bear large litters. Their position low on the body facilitates the connection required for the calf to feed effectively in the water.
The Unique Mechanism of Nursing
The ability of the calf to nurse completely underwater is central to hippo maternal care. While a mother may occasionally nurse her calf on land or in shallow water, deep-water feeding is common and necessary for the semi-aquatic lifestyle. The calf takes a deep breath before submerging its head and body beneath the water to find the mother’s teat.
Once latched, the calf seals its mouth tightly around the teat, preventing water from being ingested along with the milk. Crucially, the young hippo can automatically close its nostrils and ears, a reflex that keeps water out of its respiratory passages. This adaptation allows the calf to feed for extended periods without having to surface for air. The mother’s milk is ejected directly into the calf’s mouth, a rapid process that maximizes feeding efficiency while submerged.
Other Distinctive Hippo Anatomy
The hippo’s body features are designed to support its amphibious existence. The placement of its sensory organs is a primary example of this adaptation, with the eyes, ears, and nostrils all located on the top of its head. This arrangement allows the hippo to remain almost entirely submerged, using the water for weight support and temperature regulation, while still being able to see, hear, and breathe.
The hippo’s skin is both extremely thick and surprisingly sensitive. The outer layer is prone to drying and cracking when exposed to the sun, which is why hippos must stay near water or mud. To combat this, their skin secretes an oily, reddish-orange substance.
This secretion is a blend of hipposudoric acid and norhipposudoric acid, which serves as a natural sunscreen by absorbing ultraviolet light. The compounds also possess antiseptic and antibiotic properties, helping to protect the hippo’s skin from infection in the bacteria-rich water.