KINGDOM: Animalia (Animals)
PHYLUM: Chordata (Possessing a notochord)
CLASS: Mammalia (Mammals)
ORDER: Artiodactyla (Even-toed Ungulates)
FAMILY: Hippopotamidae (Hippopotamuses)
SUB-FAMILY: Hippopotaminae (Hippopotamuses)
GENUS: Hippopotamus (Hippopotamus)
SPECIES: Hippopotamus amphibius (Hippopotamus)
Hippopotamuses are endemic to Africa. Hippos are found in the rivers and lakes of the northern Democratic Republic of the Congo, Uganda, Tanzania and Kenya, north through to Ethiopia, Somalia and Sudan, west to The Gambia, and south to South Africa.
Hippopotamuses have barrel shaped bodies and short, stumpy legs. They have large heads, broad mouths and nostrils at the top of their snouts. They also have large curved canines, which are exposed in aggressive displays. Their hairless skin is tones of a purple gray or slate color, with brownish pink coloring around their eyes and ears.
Since hippos are semi-aquatic, they prefer shallow lakes, rivers, and swamps, with water that is deep enough to submerge their entire bodies (to protect their sensitive skin). Herds like sleeping in close groups together in shallow water during the hot daylight hours.
Hippos are herbivores (plant-eaters). They will eat leaves, wood, bark, stems, flowers, shoots, grasses, and reeds. Hippos do not use their teeth to chew their meals, and instead they tear and soften the grasses to prevent any nutritive loss. Although hippos have a four-chambered stomach, they don’t regurgitate their food to chew it again.
Hippos are a very social species, usually living in groups (called schools) of about 20 to 100 individuals. These schools are mostly made up of females and young, and are headed by a dominant male (although some subordinate, non-breeding males may also be tolerated in the group). Dominance is asserted by using the canines as both threat displays and weapons. Losing males are forced to retreat and live in bachelor herds or alone in marginal habitats. Hippos are territorial and their territories are marked by the dominant males by spraying dung and urine as well as wheezing and honking.
Hippos are polygynous (males will have more than one female mate at a time), and one bull will mate with several females in the school. Courtship rituals involve the male taunting the female, by pushing her out of the herd. He pursues her into deeper waters, until she becomes frustrated and lashes out and clashes jaws with him. He then forces her into submission and mounts her, forcing her head under the water.
As the due date draws near, a pregnant hippopotamus becomes very protective of her unborn offspring. She becomes highly aggressive when any animal threatens to come into contact with her. After a gestation period of about 10.5 months, a single calf is born, generally underwater. Once the calf is born, the mother remains isolated from the herd, remaining with her baby for several days to two weeks. Males are very protective over both the females and calves in the herd and will often attack anything that poses a threat. Calves are weaned at about one year old. Hippos will reach sexual maturity at about 3.5 years old. They can live up to 55 years.
Besides humans, hippos don’t have many natural predators. Occasionally lions, hyenas, and crocodiles will prey on young hippos.
The biggest threat to hippos is habitat loss and unregulated or illegal hunting. As humans encroach on hippo habitat, hippo-human conflicts increase. Hippos are said to kill more people in Africa than any other animal, because they will attack when they feel threatened. Because hippos also raid human crops and cause damage by grazing and trampling on crops, conflict is exacerbated.
Did you know?
- Hippos can seal up their ears and nostrils to be water-tight
- Baby hippos can suckle underwater
- They are primarily nocturnal animals
- The name hippopotamus derives from the Greek for ‘river horse’
- It is very difficult to tell males and females apart