They spend four to five hours a day eating and can consume up to 68 kg of food at a time. They feed mainly on grasses, sometimes on aquatic plants, and in the absence of preferred food, on other plants. There are also cases of scavenging and carnivorous behavior, predation and cannibalism, although hippos' stomachs are not adapted to digest meat. These are unnatural behaviors, perhaps caused by a lack of proper food. However, the authors of the Mammal Review journal claim that carnivorousness is natural for hippos. According to them, a meaty diet is typical for this group of animals, as their closest relatives - cetaceans - are carnivorous.
