A vital link in nature

PUBLISHED : Monday, 21 October, 2002, 12:00am
UPDATED : Monday, 21 October, 2002, 12:00am

A 4.5-tonne hippopotamus opening its massive jaws and showing a row of blunt-ended teeth is enough to frighten anyone - but sometimes a herd of more than 100 animals may gather in a river! They 'yawn' not because they are tired, but to warn others or to attract a female.

Hippos are commonly found in African rivers and marshes. They spend most of the day submerged in water, with just their eyes, ears and nostrils above the surface. Though clumsy-looking on land, they are almost weightless in water and move gracefully on the river bed.

Hippos are seldom seen on land during the day because their skin quickly loses moisture in the sun. To counter this, the skin glands secrete a reddish film of sweat which covers the body and helps cut out ultra-violet radiation. So if you happen to see a pink hippo, it is using its protective suntan lotion!

In the evening hippos come out of the water to feed. With teeth which act as cutting and grinding machines, they can eat tough spiny grasses that are not suitable for goats or zebras. This is important as they are not competing for the same food sources and so can live peacefully with other grass-eating animals.

Although they eat on land, hippos excrete in the water. Their droppings act as a fertiliser and stimulate the growth of plants, and therefore fish, in the river. Thus they form an important link between terrestrial and aquatic ecosystems.

WWF HK is a charity that aims to build a future in which people can live in harmony with nature. For information, call 2526 1011 or e-mail to http://www.wwf.org.hk