1. The ears and nostrils of a hippopotamus close automatically when it goes underwater.
2. A hippopotamus does not sweat; rather it excretes an oily, red liquid that protects its skin. This red liquid has given birth to the myth that it sweats blood.
3. A hippopotamus often yawn as a threatening gesture. While yawning, it displays its long, thick, razor-sharp canine teeth. This, in turn, deters its enemies.
4. Hippopotamuses have practically no hair. They have a very smooth skin, which is quite delicate.
5. A hippo is the third biggest animal on land. It is slightly smaller, but heavier, than a white rhinoceros.
6. Hippopotamuses spend most of their day in water.
7. The tusks of a hippopotamus are even more valuable that that of an elephant, since they do not turn yellow with time.
8. The tusk-like incisors and canines of a hippo grow continuously, throughout its life.
9. Hippopotamuses are territorial in water, where each male hippo controls a small stretch of the river.