Researchers have identified the chemicals responsible for the timeless myth that hippopotamus sweat blood. The blood red secretion is a familiar sight to anyone who has come face to face with a hippo.
"It's all over their back, face and behind their ears. It really does look like blood is pouring down them, "Craig White, a zookeeper at Whipsnade Wild Animal Park in Britain was quoted by Nature as saying.
Kimiko Hashimoto and his colleagues at Kyoto Pharmaceutical University, Japan, revealed that hippos' secretions are neither blood nor sweat, but a mixture of pigments that function both as sunscreen and antibiotic. This mixture keeps hippos' cool and protects them from the harmful effects of the sun, reports webindia123.com
According to independent.co.uk a team at the Kyoto Pharmaceutical University in Japan tested the "red sweat" collected from a specimen at the Ueno Zoological Gardens in Tokyo by "wiping [its] face and back with gauze".
To their surprise, the team led by Yoko Saikawa discovered that although the sweat is alkaline when it is secreted, as it turns brown it becomes a strongly acidic substance - hundreds of times more powerful than vinegar - that works as a strong antiseptic. That could be useful, scientists suggest, to neutralise infection in any open wounds that three-ton fighting males might inflict on each other with their tusks.
But the thick layer also acts as a sunscreen and further studies discovered that it absorbs light, particularly in the ultraviolet range, just like commercial sunscreens. Being such a thick, sticky substance, it tends to stick to the skin for the day-long baths that hippos prefer, when they will linger with only their eyes, ears and nose above the waterline.
The hippopotamus - or "river horse" - is a belligerent creature, which puzzled the ancient Greeks by apparently sweating blood. In fact, the thick red substance, which oozes from glands all over its skin, is one of the hippo's many ingenious survival tools. The enormous relative of the pig has carved out a unique amphibious life for itself - which requires some specialised equipment.
Hippos consume as much vegetation as they can during the night, when they are shielded from the searing heat and sun. At dawn, they retire into water and spend their days resting, squabbling and, most importantly, digesting.
Wayne Boardman, head of veterinary services at the Zoological Society of London, UK, told: "They are adapted to eating poor quality food stuffs, but to be able to get nutrition out of these, they need to be able to eat for long periods of time."
Because it is so important for hippos to eat a vast amount, they must venture out in the sun from time to time, to top up on their nightly binge. But a traditional sunscreen - like fur - is not practical if you spend half your time submerged in water, inform BBC.