Hippo’s Sweat Red

The hippopotamus or hippo mystified ancient Greeks because it appeared to sweat blood. Although hippos do sweat a red liquid, it isn’t blood. The animals secrete a sticky liquid that acts as a sunscreen and topical antibiotic.

Initially, hippo perspiration is colorless. As the viscous liquid polymerizes, it changes color to red and eventually brown. Droplets of perspiration resemble drops of blood, although blood would wash away in water, while hippo perspiration sticks to the animal’s wet skin. (Source)