A Hippo's Pink Hue Is Not Milk

Hippo milk is white or cream-colored, not naturally pink. The pinkish or reddish appearance on the skin comes from a separate viscous secretion produced by skin glands. It is initially colorless, then turns red and later brown. Researchers identified the pigments hipposudoric acid and norhipposudoric acid in it. Laboratory studies found that these compounds absorb ultraviolet light and inhibit the growth of some bacteria; this does not mean the secretion provides complete protection from sun or all infections.