There was/is a belief that hippos sweat blood! This myth came about because of the dark red colour of the sweat. But believe me this is not blood; nor is it ordinary sweat…
As the African sun bakes down on the backs of Africa’s two hippopotamus species, they have had to evolve a mechanism to combat the UV rays. They can be exposed to the sun for up to 16 hours a day, and although the water prevents the lumbering beasts from getting overheated, it doesn’t offer much in the way of skin protection! Humans are not the only ones concerned with SPF (Sun Protection Factor). This is is where the ‘blood-red’ sweat comes in and hippo sunscreen is created.
One could argue that it is not strictly ‘sweat’ as it is produced by glands under the skin rather that in it! But just what is this gelatinous substance if it is not ‘sweat’?
A series of experiments were done and the body fluids off of hippos collected. By extracting the chemical components with water scientists have been able to shed some light on this topic…
” the substance consists of two unstable and highly acidic compounds – one red, which they named hipposudoric acid, and one orange, which they named norhipposudoric acid. Although the two chemical pigments are unstable on their own, when they dry on the animal’s skin in the presence of mucus, they harden and stick around for hours. Thus, the thick, sticky mixture is tough enough to survive the hippos’ daylong soaks, all the while absorbing sunlight in both the ultraviolet and visible range ” -Saikawa
The hipposudoric acid is also a powerful antibiotic and highly acidic. The antiseptic powers of hippo ‘sweat’ help to explain how the beasts manage to remain largely infection-free despite the wounds the males often inflict upon one another with their tusks.
The hippo’s gooey antibiotic sunscreen still remains largely unresolved. It is believed that an animal synthesises it from amino acids in the presence of oxygen.
There is also a theory that it may even act as a bug repellent since flies seem averse to landing on it.
Scientists are still trying to understand how it works in the hopes of bottling it as a product meant for people. Although, I personally don’t think a sunscreen would sell if it turned people red-orange; regardless of how effective it was!
Written and photographed by Adam Bannister
Inspired by Animal Planet:
Saikawa, Yoko, et al. “The red sweat of the hippopotamus.” Nature. Vol. 429. May 27, 2004.