The common hippopotamus, Hippopotamus amphibius, resides throughout sub-Saharan Africa wherever there is water deep enough for it to submerge during the day, surrounded by plenty of grassland for grazing and foraging. These prehistoric giants grow up to 5 feet tall at the shoulder and weigh as much as 3 tons, and their diet has been much the same for at least 10 million years. While the common hippo is not in danger of extinction, the species is threatened by loss of habitat as a result of human encroachment and the continued expansion of the Sahara Desert.
Hippos graze on land; they do not eat while in the water and aren’t known to graze on aquatic plants. They prefer short, creeping grass and small green shoots and reeds. While they will eat other vegetation if it’s there, they tend to avoid coarser grasses that are more difficult to digest, and do not root in the dirt for buried roots or fruits.
The hippopotamus is well adapted to thrive on its relatively nutrient-poor diet. While hippos do not ruminate or chew their cud like many other grazing animals, they do have a multi-chambered stomach and a much longer intestinal tract than other grass eaters. This slower rate of digestion ensures the animal gets the most possible nutrients out of the grass it consumes. The canines and incisors in the front of a hippo’s mouth can grow 15 to 20 inches long, and are sharpened as they are ground together during grazing.
The nocturnal hippopotamus leaves the water at dusk and follows the same path to grazing grounds. Although they commune in the water in groups, grazing is a solitary activity. Hippo paths are ever-widening circles as far as two miles away from their water home. Hippos tread these familiar paths every night for five to six hours, pulling grass up with their lips and tearing it with their teeth before swallowing, rather than chewing.
If the water dries up or there is a shortage of food, hippos will migrate as far as 30 miles away to find a new home. Male hippos are territorial, but their territories are related to mating rights, not food. Grazing grounds are shared freely amongst all hippos in the area. In some isolated areas, individual hippos have been observed consuming carrion, but this is believed to be a result of some sort of illness or deficiency and not a universal change in the diet or feeding habits of the species, the University of Michigan's Animal Diversity Web reports.
In many areas, notably the Okavago Delta in Botswana, hippos are responsible for altering their environment as they graze and creating habitats for other animals. Their trails away from the water to grazing grounds serve as flood drains during the rainy season. As hippo gullies fill with water, they become water holes for the entire area during the dry season. Flooded hippo paths create shallow lagoons where smaller fish can live away from the larger river animals that prey on them.
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