Image: Paul Maritz via Wikimedia Commons

Studies have shown that hippos produce pigmented secretions that actually function as highly-effective sunscreen — protecting their bodies from burning in the sweltering heat of their natural habitats.

Hippopotamuses are native to central and southern Africa, where sub-Saharan sunlight serves as a formidable daytime enemy. These land animals spend more than half their day submerged in water sources to keep their bodies cool and only leave these refreshing sanctuaries in the nighttime to graze across the surrounding plains.

Even beneath the water of streams and lakes, however, the animals are exposed to constant sunlight, leading scientists to wonder at the mechanism behind the hippo’s physical lack of sunburn.

Image: Vince Smith, Flickr
Image: Vince Smith, Flickr

Mucous-like secretions ooze out of their bodies from large glands beneath the skin. These secretions are composed of orange and red pigments that possess both antimicrobial and UV-protecting components.

Japanese researchers tested this hypothesis at the Ueno Zoo in Tokyo by collecting samples of these secretions by wiping them off the hippos and studying their chemical composition. The results revealed that the pigments were primarily hipposudoric and norhipposudoric acids and both presented extensive UV absorption properties.

These 5,000- to 8,000-pound semi-aquatic animals have eliminated the need for hair growth by biologically producing their own protective sunblock.

In addition, the hipposudoric compound was analyzed for its incredible antibiotic capabilities. This secondary discovery serves as an important evolutionary development due to the often combative nature of hippotamuses, frequently resulting in massive gashes on account of fierce attacks with massive tusks. Excretion of the oily substance prevents the cultivation of bacteria in open wounds.