There is fossil evidence that many Malagasy Hippos were hunted by humans, a likely factor in their eventual extinction. The hippopotamus is semi-aquatic mammal, inhabiting rivers and lakes in sub-Saharan Africa in large groups of up to 40 hippos. During the day they remain cool by staying in the water or mud; reproduction and childbirth both occur in water, where territorial bulls preside over a stretch of river. Hippos emerge at dusk to graze on grass. While hippos rest near each other in territories in the water, grazing is a solitary activity and hippos are not territorial on land.
The eyes, ears and nostrils of hippopotamus are placed high on the roof of the skull. This allows them to be in the water with most of their body submerged in the waters and mud of tropical rivers to stay cool and prevent sunburn. Hippopotamuses need water deep enough to cover them, within commuting distance of pasture.
Hippos must submerge into the water because their thin, naked skin is vulnerable to overheating and dehydration. Hippos average 3. Hippos are approximately the same size as the White Rhinoceros and experts often debate on which is the next largest land animal after the elephant. Male hippos appear to continue growing throughout their lives, whereas the female hippos reach a maximum weight at around the age of 25 years. The greek word 'ceros' means horn. Both male and female Indian rhinos have only one horn.
The horn which is made of keratin, the same substance of human fingernails, starts to grow after 6 years of age. In most adults the horn reaches about 25 centimeters, but has been recorded up to The nasal horn curves backwards from the nose.
Its horn is naturally black. In captive animals, the horn is frequently worn down to a thick knob. The rhino's in Africa white and black use their horns for attacking while the Indian rhino uses its incisors. The white rhino needs open undulating woodland with plenty of grass and permanent water.
Hippos are semi-aquatic mammals so rivers and lakes, not necessarily very deep, with pools of slow moving water and banks with good quality grazing is an ideal habitat. Both hippos and rhinos are herbivores. The black rhino is found in South Africa, Rwanda and Zimbabwe. The Sumatran and Javan rhinos are found in Sumatra and Java respectively.
The Indian one-horned rhino is found in the Assam region of India and in Nepal. Hippos are found all over Sub-Saharan Africa.
White rhinos are less aggressive and more sociable than black rhinos and can be seen in groups of ten or 15 and live according to a strict social structure. Black rhinos travel alone. The Indian Rhinoceros forms a variety of social groupings. Adult males are generally solitary, except for mating and fighting.
Adult females are largely solitary when they are without calves. Mothers will stay close to their calves for up to four years after their birth. Male rhinos can greet each other in a very friendly manner and play with stick and twigs together.
Hippos spend most day soaking in water. They cannot swim but often submerge and resurface every 3 to 5 minutes to breathe. They can also sleep underwater and automatically resurface without waking. There are estimated 17, white rhinoceros remaining in the wild and about black rhinos. In there were only 50 Javan rhinos in the wild, Sumatran rhinos and one-horned Indian rhinos in the world. There are an estimated , to , hippos throughout Sub-Saharan Africa; Zambia 40, and Tanzania 20,—30, possess the largest populations.
Since the world rhino population has declined by 90 percent, with five species remaining in the world today, all of which are endangered. The Javan and Sumatran rhinos are critically endangered. An adult hippo can reach a weight of 7, pounds. Hippos generally spend the day submerged in water, with their ears and nostrils protruding above water.
At night, they come onto land to feed on grasses. They are known to be quite aggressive toward humans. Hippos need permanent open water like rivers, dams, or pools in rivers where they can submerge, with sandbanks where they can bask in the sun for periods of time. They also need enough grazing grass in the area. Hippos are semi—aquatic and gregarious animals. They gather or form pods schools of up to 30 animals or more depending on the water level and time of season.
Hippo pods consist mainly of cows and young hippos with a matriarch and a dominant territorial bull in control of the territory. Single bulls are also often found. Cows with very young calves often stay on their own for a few months before rejoining the pod.
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