The hippopotamus possesses skin remarkably adapted to its semi-aquatic life. This unique integumentary system functions as a comprehensive protective barrier, essential for the animal’s survival and ability to thrive.
Physical Attributes
Hippo skin is notably tough. An adult hippo’s hide can reach an impressive thickness of up to 6 centimeters (approximately 2.3 inches), particularly on its flanks and back. This substantial dermal layer contributes significantly to the animal’s overall mass, accounting for a notable 18% of its total body weight. The skin’s surface typically appears grayish-brown, rough, leathery, and deeply wrinkled, especially around joints and folds.
Beneath the thin outer epidermal layer, the underlying dermis is exceptionally dense and durable. Unlike many large mammals, hippos have minimal subcutaneous fat; their immense bulk is primarily muscle and thick, robust skin. This composition contributes to their density, enabling them to move along riverbeds rather than simply floating.
Specialized Structure and Composition
Hippo skin features a multilayered construction. A thin outer layer can be prone to minor abrasions, but the much thicker dermal layer beneath provides immense strength. This inner layer is densely packed with connective tissues and structural proteins, contributing to its durability and tensile strength.
Specialized glands embedded within the skin secrete a distinctive reddish, oily fluid. Often mistakenly called “blood sweat,” this substance is neither blood nor true sweat. Chemically, this fluid is alkaline, ranging from a pH of 8.5 to 10.5. This secretion acts as a natural moisturizer, sunscreen, and antiseptic agent, maintaining skin health.
Adaptations for Protection
Hippo skin serves several protective functions. Its strength shields against physical abrasions from submerged rocks, branches, or rough terrain. This durability minimizes damage from constant interaction with their aquatic and terrestrial environments.
The thick hide provides substantial defense against threats, including predator bites like crocodiles. It also protects during aggressive encounters between rival hippos, shielding them from powerful tusks and teeth. While tough and able to withstand puncture wounds and slashes, the skin is not impervious. Larger caliber projectiles can penetrate it, and a hyena’s strong jaws can compromise the skin of a deceased or weakened hippo.
Skin Health and Unique Care
Despite its toughness, hippo skin is susceptible to dehydration and sun exposure when not submerged. Hippos lose water rapidly through their skin, requiring constant moisture for integrity. Without adequate hydration, their skin can dry out and crack, leading to health issues.
To counteract these vulnerabilities, hippos spend most of their day submerged. This keeps their skin moist and protects from intense ultraviolet radiation. Their semi-aquatic lifestyle is crucial for temperature regulation and preventing sunburn. The reddish secretion from their skin glands further aids this maintenance.