Hippopotamuses are great, defiant beasts. Lurking in the water, their heads propped on the surface, they look slow and lumbering, forever stuffed from a meal. But they’re terrifyingly nimble, with jaws that snap open like a bear trap and legs that propel them through water and land. 

They’re cute, but they’re also vicious. Their jaws seem designed to eat animals whole, but they’re primarily vegetarians, eating water plants, grass, and other vegetation. They seem like solitary hunters, but they hang out in large groups. 

Hippos always seem to be defying expectations, whether they’re eating watermelons in one big chomp, storming out of the water after a nap, or gently nuzzling alligators.  

In honor of World Hippo Day, here are nine facts about these robust creatures: 

1/ Hippos can weigh more than 8,000 lbs and can grow up 17 feet in length. 

2/ Hippos can eat more than 80 pounds of vegetation a night, when they're busiest chowing down.  

3/ Hippos can live up to 50 years. 

4/ They love the water. They spend up to 16 hours submerged daily, can hold their breath for five minutes, and are great swimmers.  

5/ They also secrete a red, oily liquid that moisturizes their skin and acts as a sunblock.

6/ Hippos mark their territory with something call a dung-shower: a hippo walks backward while simultaneously urinating and defecating, creating a boundary.

7/ Baby hippos are vulnerable to crocodiles, alligators, lions, and hyenas. 

8/ The first hippo fossil is from 16 million years ago. 

9/ There are around 125,000 hippos left in the world. Their historic range is throughout most of central and southern Africa, but habitat loss has driven them mostly to protected areas.