Reproductive Systems Research Task
Grace Mackay

Hippopotamus comes from a Greek word meaning water or river
Hippos are the third largest land mammal species on earth, after
elephants and the white Rhinos. They weigh in to be around 3,600 Kilograms and
can reach up to over four and a half metres long and one and a half metres
tall. Their skin colour varies, from brown to a greyish shade.

They are completely hairless; therefore they produce a
special sweat that is red and acts as sunscreen, insect repellent and
antibiotic lotion, all in one. During the day Hippos stagger around; usually
resting, playing and sometimes they fight in lakes, rivers and swamps. During the
night they spend hours grazing on land. They can run up to speeds of 48kph but
they tend to gallop gracefully throughout the bottoms of rivers and lakes.

Hippos have wide snouts, which is beneficial for grazing through tough African grasses. Their eyes,
ears and nostrils are on the top of their heads, and they close up when they go
underwater. The entire diet of the Hippopotamus is several species of grass,
and they will eat up to 40kg of it each night. They eat about half as much as larger
mammals but because they don’t use much energy their body can get by on less
food. They gather in groups usually around 15, called bloats, pods, sieges or herds with a territorial bull that’s in charge of the group. The hippo is
native to 29 African countries and kill nearly 3,000 people every year.

The button for the footage above gives an insight to how Hippos swim, interact and behave in captivity but also an idea of what they look like and the structure and size of their features.


The Hippopotamus can be found living in the lakes and rivers. They tend to stay in groups and the size can vary from small groups, to large, which can be as much as thirty members. Hippos like to live in deep bodies of water , when mothers have their young, they will often carry them on their backs so that they aren’t as far below the surface and can come up for air.

There are two species of Hippos, the common Hippo lives mainly in the Eastern part of Africa, around the Sahara. They are a more aggressive type of Hippopotamus, known for eating the crops that villagers plant for their own needs.

The Habitat for the Pygmy Hippopotamus is different as they tend to live in the swamplands in West Africa, they like murky water and it doesn’t bother them if the water is deep or filled with rocks. These factors don’t seem to be much of a burden to them because they are so much smaller in size, hence the word “Pygmy” Hippopotamus. 

The number of pygmy hippopotami decreases every year because of the increasing population of the villagers. They continue to take over the Hippos land for their own advantage of growing more crops. To this day, this is why you will only find the Pygmy Hippopotamus in the forest area of Western Africa. Not many Hippos are taken from the wild, but many born in captivity and Zoos will maintain their entire life there, to ensure that the population is increasing.  


Fertilisation occurs for Hippos in the female; uterus. Therefore they reproduce identically like humans, sexually. The sperm is combined with the egg and fertilisation occurs inside the female hippopotamus.  The Hippopotamus reproduces by cross – fertilisation, which means that one male and one female that are individuals but of the same species perform copulation to create a fertilised egg. One egg is released verses millions of sperm. This type of fertilisation enables animals to reproduce in a native environment because the sperm can swim to the egg without the gametes (sex cells) from drying out. Males often have a penis to transfer the sperm to the egg internally.

This photo above gives an insight to what a small (most likely female) jaw span is, in comparison to a very large 3,600kg bull (male hippo) jaw span.


In the hippo, the embryo develops in the Uterus (which is internal), but before that the fertilised egg develops in the mother’s womb. From there it develops into an embryo, which is nourished by the placenta. The Hippopotamus uses a viviparous process, which means that the fertilised egg develops inside the mother and is born a living mammal. The gestation period of the hippo is around 8 months, and their young (Calf) can often reach between 55-60kgs.

Females can be ready to start breeding around three or four years of age, but as the males are older the average is seven or eight. However males aren’t allowed to breed within their herd unless they are the dominant bull. Most of the time breeding occurs at the end of the wet season, these are ideal conditions for hippos as the rain brings them lots of water to be in during the day, it brings them cool temperatures so they don’t use up to much energy in the sunlight. There is plenty of food in the wet season therefore they absorb in the mating process. Although most of the breeding doesn’t occur until towards the end of the wet season, the hippos can actually breed at any time throughout the year. Females that don’t have the role of parental care will go through cycles where they can conceive, and during this time the dominant bull will be around the female frequently, and this time frame doesn’t last anymore than three days. Females give birth to their young in the water, doing this helps the mother to conserve her energy. Once the calf is born they are able to quickly get to the surface of the water to take their first breath. Almost always only one calf is born but there has been known occurrences of the occasional set of twins.

The button above will link to the Toledo Zoo website in Ohio, USA. Where there will be live footage of the Hippopotamus/s that live in the zoo. (if you can't see the Hippos, that will be because it is either night time or they are out of the frame of camera) There are also other options to look at live footage of other animals too.

Parental Care

When the female is soon to give birth to her young she leaves the pod for a couple of weeks to give birth and create a tight bond with her calf. The first few days the mother and baby don’t leave the water for food. The mother ensures her baby is strong enough before they begin to graze at night for grass. The mother nurses their calf under the water on average for about 8 months, but they can do so up to a year. Young Hippos can stay underwater for about 30 seconds but adults can stay underwater for as long as 6 minutes. The calves can suckle underwater by wrapping their tongue tightly around their mother’s teat to suck. Baby hippos begin to eat grass after about 3 weeks after being born, but the mother continues to suckle it for about a year. Newborns often rest upon their mother’s backs. If the rare set of twins is born, only one will survive, as the mother will abandon the other one, as she will only care for one calf. The mother gives very generous care to her calf and, and takes a great deal of time to ensure her calf grows to its full capabilities. The Hippopotamus would be a K-selection of parental care as they produce few (one) offspring, a long period of time is taken into parental care, they have a fair life expectancy (50 years) and they can reproduce more than once in their lifetime.

A hippo becomes increasingly aggressive when they have young to care for. Hyenas and lions tend to see baby calves as a very tasty meal but they will only go for the calf if it is a considerable distance away for the mother, but they wont take the risk of the calf if the mother gets too close, as they know she could kill them. This level of aggression can be a disadvantage because if a fight is happening in the water the baby can often get caught in the middle and suffer with serious injury or even death.

The button above will link to a video of a mother and her calf. It will show how the calf suckles on her mothers teat under the water for milk. (skip towards the end of the clip to see this)


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2 years ago

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