Mystery solved by bloody hippopotamus

Pigment compound responsible for the reddish shine

Hippopotamus © IMSI MasterClips
Read out

Researchers at the University of Kyoto have solved the mystery of the colored "sweat" of hippos. Already in antiquity the phenomenon was known, which brought the myths to the animals, they sweat blood. Now it has been found that the secretions are neither blood nor sweat, but a mixture of pigments that serve as a sunscreen, antibiotic and to regulate body temperature.

For the investigation, the researchers have taken swabs of the substance from the heads and backs of the two hippos Satsuki and Jiro in the Tokyo Zoo. Subsequently, the substance was examined for its chemical composition and thus the two pigments were identified. These compounds give hippos their reddish appearance, Japanese researchers are convinced. They believe that the two substances are produced as metabolites of amino acids that produce proteins.

By isolating the chemicals, the researchers have verified the thesis that the "sweat" takes on a role as a sunscreen and antibiotic. It was tested how much of the spectrum of the sun is absorbed by the pigments. The researchers found that the pigments shield the hippos from ultraviolet radiation. The red pigment also serves as an antibiotic and prevents the growth of the pathogens Pseudomonas aeruginosa and Klebsiella pneumoniae, so the hippos are also protected from bacteria. In addition, the substance regulates body temperature.

This triple function of the pigments is very useful for the animals that live in Central Africa and the Nile Valley. They spend a lot of time in the sun and numerous battles make them susceptible to wound infections. The hippos produce more of the pigments when they are on dry land. Furthermore, they can store the blood-red glow for a few hours before they lose their luster.

(PTE, 28.05.2004 - NPO) Display