Hippopotamidae, commonly known as hippos, are large, mostly herbivorous mammals native to sub-Saharan Africa. They are characterized by their massive bodies, large mouths, and short legs. Hippos spend much of their time in water, which helps keep them cool under the hot sun. They are social animals, often found in groups called pods. There are two main species of hippos: the common hippopotamus and the pygmy hippopotamus. The common hippopotamus is much larger and more widespread, while the pygmy hippopotamus is smaller and more elusive. Both species are considered vulnerable due to habitat loss and poaching for their meat and ivory tusks.