Hippos Secrete Natural Sunscreen

For centuries, observers noted a strange phenomenon: hippos appearing to sweat blood. This striking red fluid, however, is neither blood nor sweat, but a unique, oily secretion produced by specialized glands in their skin. Initially colorless, the substance quickly polymerizes in the air, turning a vibrant reddish-orange before eventually drying to a brown, protective layer. This remarkable gel serves as a multi-purpose tool perfectly adapted to the hippo's semi-aquatic lifestyle, where its sensitive skin is constantly exposed to both intense sun and murky water.

Scientists have identified the two key pigments responsible for this effect: the red hipposudoric acid and the orange norhipposudoric acid. Together, these compounds are highly effective at absorbing ultraviolet light, acting as a powerful, broad-spectrum sunscreen that shields the hippo’s largely hairless skin from burning. Furthermore, these acids are potent antibiotics. They inhibit the growth of common pathogenic bacteria, a crucial function for an animal that frequently sustains deep wounds (Review) from territorial fights. This natural antiseptic helps prevent infections, allowing the hippo to heal quickly in its bacteria-rich environment.