Hippo sun cream
Stories from Physics
for 11-14
14-16
Hippopotamuses secrete a clear fluid that helps to control their body temperature. The fluid turns red-brown within a few minutes of release and gave rise to the myth that the creatures sweat blood. Researchers have found that the fluid blocks both UV and visible light of wavelengths 200-600 nm and so protects the animals from sunburn. The fluid contains red and orange pigments which researchers have labelled hipposudoric and norhipposudoric acid.
References
F. Gowland, Hippos lead the way in multipurpose sun screen. Journal of Experimental Biology, vol. 207, no. 19, 2004, p. v.
Y. Saikawa, K. Hashimoto, M. Nakata, M. Yoshihara, K. Nagai, M. Ida, & T. Komiya, The red sweat of the hippopotamus. Nature, vol. 429, 2004, p. 363.
