San Diego Zoo Global
San Diego Zoo: Hippotpotamus
This resource presents detailed information about the hippotpotamus, including several photos and an audio clip.
BBC
Bbc: Nature Wildfacts: Hippopotamus
This resource provides detailed information about hippopotamuses.
Smithsonian Institution
National Museum of Natural History: Hall of Mammals: Hippopotamus
Brief overview of the hippopotamus and accompanying photos demonstrate the physical adaptations that allow this animal to survive in its habitat.