Latin Name: Hippopotamus amphibius
Lifespan: Both the males and females live up to 40 years of age.
Sexual differentiation:
The males are much larger than the females, reaching 3000 kg and the females about 2000 kg. The male’s tusks (incisors) are longer than the females, up to 50 cm in length.
Social grouping:
The collective name for a group of hippo is a “raft of hippo”. A typical family unit consists of 1 dominant male, any number of females with their young. The dominant bull is extremely territorial and protective over the females. Males that are not dominant wonder on their own or in small groups of males, often avoiding any confrontations with any territorial bulls in the area.
Reproduction:
Mating takes place in the water. After a gestation of about 8 months the female gives birth in shallow water. The female seems to somehow know the sex of her calf before giving birth as a pregnant cow that has a male calf in her will often leave her family group to give birth in a separate river or dam.
The dominant male reacts very aggressively to new males trying to join his family group even if they are newborn or his own, so for this reason the pregnant female leaves the group to give birth and stay on her own with the newborn male calf until he is strong enough to move quickly and hopefully avoid dangerous confrontations with the dominant bull when they rejoin the rest of the family.
When pregnant with a female calf, the mother will normally give birth in the same river or dam where the rest of the family are.
The cow’s milk has a very thick texture, almost like yogurt. The thick milk makes it possible for the calf to drink from its mother while under water without the milk dissolving too much.
Territoriality:
The size of the male’s territory depends on a number of different factors. If there is a shortage of water in the rivers and dams, hippo start to congregate where ever they can find water, often resulting in a lot of fighting between the males’. With so many males in close proximity, the territories soon become a lot smaller with all the competition. An over-population of hippo can have the same effect. The amount of good grazing grass in an area can also affect the amount of competition between dominant bulls.
The male marks his territory by scattering his dung onto vegetation like trees and bushes. He does this by facing his behind towards the vegetation and as he drops his dung he starts to swing his tale continuously and rapidly from side to side, resulting in the dung being sprayed onto the vegetation. The male will often scatter dung in the same place on land as well as in the water, leaving his own scent throughout his territory.
Feeding habits and sun protection:
Hippos’ are classified as herbivores but have been known to feed off the carcasses of animals, this being very rare of course.
They have a very thin epidermis that very sensitive to too much sun. For most of the day they stay submerged under the water to protect their skins from the sun. If a hippo stays out of the water too long on a hot day, its skin starts to dry out and over extended periods out of the water its skin starts to crack open into wounds.
The perspiration of hippo gives limited protection from the sun acting as a form of sun-block and an anti-bacterial agent. Their perspiration is pink in colour which often looks like blood with excessive sweating.
Hippos’ leave the water after sunset and spend most of the night out grazing. Early in the morning before the sun rises is the time when they return back to the water, where they stay for the rest of the day until night falls again.
During the summer months there is normally a lot of grass, so the hippos’ might only walk 5 or 10km in a night to feed. In the dryer winter months or drought there is less grass, forcing the hippos’ to walk as much as 15 to 20km or more in a night to find food.
Most dangerous mammal in Africa:
Statistically hippos’ kill more people than any other mammal in Africa. The people that get killed are normally living in rural areas where there is no tap water. These people need to fetch water and bath in rivers and dams and often get caught between the hippos’ and the water when the hippos’ are making their way back to the water in the early morning. Hippo often react very aggressively by attacking when their pathways are blocked, resulting in many deaths every year.