Rhino horn is believed by some people to have magical properties. As a result, thousands of rhinos have been slaughtered for their horns and they are now in danger of becoming extinct. Hippopotamuses are huge, pig-like creatures that live in Africa. They have enormous heads and the biggest mouths of any land mammal. When a hippo yawns, it opens its mouth wide enough to swallow a sheep, but it eats only grass.
Hippos spend their days wallowing in rivers or swamps, and usually feed only at night.
A hippo's eyes, ears and nose are all on the top of its head, so they remain above water even when the rest of the body is completely submerged. Black rhinos are killed by poachers for their horns and are among the world's rarest animals. The Indian elephant can live to be over 70 years old. A white rhino's horn can grow to over 1.5m long. Elephant tusks can grow to almost 3.5m long.