There are only two species of hippopotamus in the world today. There are an estimated 125,000 to 150,000 common hippopotamuses in the world. Pygmy hippo numbers are even fewer, and there are an estimated 2000 to 3000 remaining in the world.
The word "hippopotamus" is Greek for river horse, which is a fitting name for the semi-aquatic herbivore. Diminishing habitat and heavy hunting have reduced the hippo species nearly to the point of extinction. The pygmy hippopotamus has been placed on the endangered species list to help preserve the remaining population. Hippos are a popular attraction in zoos because they are so rare and seldom seen by humans in their natural habitat.