(Zoology) An example of an animal with a red sweat is the hippopotamus. The "sweat" of the hippos is excreted from a special gland on their skin. It is initially colorless but soon becomes rusty or "bloody" in color. This sweat appears to provide protection against sunburn, heat, and microbes, thereby acting as a natural sunscreen and antibiotic. The color is due to the pigments such as hipposudoric acid (red pigment) and norhipposudoric acid (orange pigment) capable of absorbing UV light in the 200-600 nm range.