The hippopotamus, more commonly referred to as the hippo, is a large mammal that can be found in sub-Saharan Africa. Its name, derived from ancient Greek, translates to "river horse," alluding to its affinity for water and its great heft and might. The hippopotamus' closest living relatives belong to the order Cetacea, which includes whales and dolphins.

The hippopotamus is well-known for its size, and for good reason; it is the third largest extant land animal, being smaller than only the elephant and the rhinoceros. On average, the hippopotamus measures 11 to 17 feet in length, excluding its tail, which measures almost two feet in length. They also measure about five feet in height, and weigh about 3,000 to 4,000 pounds, with females' being slightly smaller than males. The heaviest known hippo weighed about 9,900 pounds.

The hippopotamus is a semi-aquatic animal, meaning that it occupies both water and land. The hippo spends most of its time in water, in particular freshwater bodies, including to mate and give birth, but comes to land at dusk to graze on grass. Despite its seeming preference for water, the hippopotamus cannot swim will and does not float in water, and is therefore rarely seen in deep water.

Despite its menacing size and frame, the hippo is not a predator but an herbivore, mostly eating grass and fruit. It is most likely simply to graze on short grass, and can eat 150 pounds of grass daily. However, it will also eat fruit that has happened to fall to the ground, and has an acute sense of hearing that allows it to detect when a piece of fruit falls from a height.

The hippopotamus' sense of hearing is not only impressive on land. Hippos have large jaws that are connected in the very backs of their skulls. This feature not only allow them to open their mouths impressively widely, but lets them hear underwater, as sound travels through the hippopotamus' jaw and enables it to hear while submerged or partially submerged in water.

The hippopotamus is not a social animal, tending only to form mother-daughter bonds. However, hippos tend to huddle together in groups in the water, a behavior that remains unexplained. Hippos seem to communicate vocally, though the purpose of their vocalizations is also unknown. On land, the hippopotamus is distinctly more solitary than in water.

Female hippos reach sexual maturity at around the ages of five to six years, while males do so at about the age of seven and a half years. It seems that hippos most commonly breed at the end of the wet season in the summer, and give birth after eight months at the beginning of the wet season in the winter. Females can reproduce about every two years. A female typically produces one young at a time, though may have twins.

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Jacob Maddox manages content for Wildlife Animals http://www.wildlife-animals.com an educational wildlife and animal website.