The hippopotamus (Hippopotamus amphibius), or hippo, from the ancient Greek for “river horse” (ἱπποπόταμος), is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the Pygmy Hippopotamus). After the elephant, the hippopotamus is the largest land mammal and the heaviest extant artiodactyl, despite being considerably shorter than the giraffe. The hippopotamus is semi-aquatic, inhabiting rivers and lakes where territorial bulls preside over a stretch of river and groups of 5 to 30 females and young. During the day they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grass. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.
Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoises, etc.) from which they diverged about 55 million years ago. The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago.
The hippopotamus is recognizable by its barrel-shaped torso, enormous mouth and teeth, nearly hairless body, stubby legs and tremendous size. It is the third-largest land mammal by weight, behind the white rhinoceros and the three species of elephant. The hippopotamus is one of the largest quadrupeds (four legged mammals). Despite its stocky shape and short legs, it can easily outrun a human. Hippos have been clocked at 30 km/h (19 mph) over short distances. The hippopotamus is one of the most aggressive creatures in the world and is often regarded as one of the most dangerous animals in Africa. There are an estimated 125,000 to 150,000 hippos throughout Sub-Saharan Africa; Zambia (40,000) and Tanzania (20,000–30,000) possess the largest populations. They are still threatened by habitat loss and poaching for their meat and ivory canine teeth.
The Kikuyu People believe that in the days of long, long ago, when the Good Lord N’gai made his plans for all the creatures upon his earth, he made the hippopotamus as an animal of the forests and plains. But the hippopotamus was greedy and, finding plenty of food all round him and no enemies to worry about, he grew fatter, and fatter and fatter. And the fatter he grew, the more he suffered from the heat of the Equatorial midday sun.
Day after day, when he waddled down to the river for his drink, he gazed with envy at the little fishes that swam in the pool which was cooled by the melted snows from far-away Mount Kenya. “Oh” he would sigh, ” how wonderful it would be if I could live, like N’gai’s little fishes, in the clear, cool, refreshing water!.” The hippopotamus pondered over his trouble for many days, and eventually decided to approach The Lord of All Creation. “Please, Good Lord N’gai” he cried loudly to the heavens upon one particularly hot day, “allow me to leave the forests and the plains. Let me live instead in the clear, cool waters of your rivers and lakes, for the heat of the fiery sun is killing me!”
“No”, replied Lord N’gai, “for my little fishes are very dear to me, and if you were to live in the rivers and lakes, you might try a change of your eating habits, and begin to eat those little fishes. That would never do. No, you must continue to live upon the dry land.” So the hippopotamus stayed sadly in his home in the forests and plains, where the sun continued to beat down mercilessly on his unprotected hide. “This is more that I can bear!” moaned the poor creature. “Please, please, Good Lord N’gai. let me leave the forests and plains, and become a creature of the rivers and lakes, I promise most faithfully that I will not eat your little fishes.”
The Great Lord N’gai thought the matter over, while he looked down upon the plains baking in the heat of the tropical sun, and eventually his heart softened. “Very well,” he agreed, ” I will allow you to live in my rivers and lakes, but how will you prove to me that you are not eating my little fishes?” “I will lie in the cool of the water by day, and at night time I will browse along the banks of the rivers, and in the vleis,” replied the hippopotamus. “I promise that I will not eat your little fishes.”
“But that will not be proof to me that you are keeping your promise!” pointed out The Great Lord N’gai. “Well then,” answered the hippopotamus, “I will come out of the water every time that food passes through my body, and I will scatter my dung on the earth with my tail. All that I have eaten will be spread out in your sight, and you will see for yourself that there are no fish bones. Surely this will be proof enough!” So this is way, to this very day, the hippopotamus comes out of the water to scatter its dung as it looks up to heaven and says, “Look N’gai, no fishes!” – and that is why hippos don’t eat fish!