Africa's a hot place, especially for a hairless animal like the hippo. That, among other reasons, is why hippos secrete a red-pink fluid that has been dubbed "blood sweat".
Researchers from Kyoto Pharmaceutical University told Nature magazine that the secretion, which has been dubbed "blood sweat", protects the hippo from various pathogens and aids the healing of wounds, as well as other important benefits.
Most animals have fur to protect them from the sun, but hippos have very little of it because they spend most of their time in the water, making it impractical. This is why the hippo also evolved with anti-UV functions as a part of their "blood sweat" secretion.
The secretion is made up of two pigments; red, called "hipposudoric acid", and orange, called "norhipposudoric acid".
Mark Ritchie, from Syracuse University, told Scientific American that it also acts as a coolant when it's secreted onto the skin, because it evaporates and cools the hippo's body.
Hippos are large semi-aquatic mammals that spend most of their lives in the water, avoiding sunlight where possible. They even sleep underwater, only rising for air every ~4 minutes - all without waking. This is where the secretion plays another role, as it prevents the hippo's skin from becoming waterlogged.