The hippopotamus, a massive, semi-aquatic mammal native to sub-Saharan Africa, spends most of its day submerged in rivers and lakes. Given its environment, which often includes stagnant water and mud, many people wonder about the animal’s potential for a strong odor. Understanding the true nature of a hippo’s odor requires examining its diet, its unique skin secretions, and its territorial habits.
The Influence of Diet and Habitat on Hippo Odor
The hippo’s diet is a primary factor in its internal biological odor, which is surprisingly mild. Hippos are primarily grazers, leaving the water at night to consume large amounts of short grasses, typically eating between 80 to 110 pounds of vegetation nightly. This herbivorous diet, processed through a specialized three-chambered, pseudo-ruminant stomach, results in a less intense internal body odor.
The more noticeable smell associated with hippos often comes not from the animal itself, but from its surroundings. Hippos spend up to 16 hours a day wallowing in pools to regulate their body temperature and keep their skin moist. These water bodies are continuously enriched by the hippo’s waste, creating a nutrient-dense but sometimes stagnant environment. The resulting odor is external and environmental—a mix of wet earth, decaying plant matter, and concentrated animal waste.
Is Hippo Sweat the Source of the Smell
A significant source of the hippo’s unique smell is a reddish secretion that was historically and inaccurately called “blood sweat.” This fluid is not true sweat, but a viscous, oily substance secreted from glands under the skin. The secretion is initially colorless, but quickly turns a vivid orange-red upon exposure to air due to the presence of two acidic pigments.
These two compounds are the red hipposudoric acid and the orange norhipposudoric acid. The pigments serve a dual purpose, acting as both a natural sunscreen to absorb ultraviolet rays and a potent antimicrobial agent. This is important because hippos are prone to cuts while fighting, and the secretion helps protect their wounds in the bacteria-laden water.
The odor of this biological secretion is often described as unique and pungent, sometimes having a slightly acrid or musky quality. While distinctly noticeable, it is fundamentally different from the smell of decomposition or fecal matter. The acidic nature of these protective compounds contributes directly to the fluid’s characteristic, slightly sharp scent.
Territorial Marking and Waste Products
The most offensive odor associated with the hippopotamus is directly linked to its territorial marking behavior. Male hippos fiercely defend their stretches of river or lake, using their waste products to signal ownership. This process involves the hippo defecating and urinating while rapidly spinning its short tail like a propeller.
This action flings the semi-liquid mixture of feces and urine over a wide radius, sometimes up to 10 meters, clearly marking the territory with a potent scent. The intentional spraying of concentrated waste products ensures the message is broadcast far and wide to rival hippos. This behavior is triggered by the presence of a stranger’s vocalizations, indicating the spray is a deliberate form of communication and defense.
The resulting smell from this concentrated, flung waste is the strongest and most unpleasant odor associated with the animal, especially near their grazing paths and resting areas.