San Diego Zoo

River Hippopotamus (Hippopotamus amphibius) The most rotund land mammal, with adults reaching roughly 4 tons; its eyes, ears, and nostrils sit on top of the skull so it can see, hear, and breathe while the rest of the body stays submerged. Its skin is 4–6 cm thick and secretes a reddish oily substance that functions as both sunscreen and antibiotic, requiring the animal to stay wet daily to avoid drying out. ...