Hippos live in eastern central and southern sub-Saharan Africa, where their populations are in decline. Their name means ‘river horse’ in Greek. They can spend up to 16 hours a day submerged in rivers and lakes to keep their massive bodies cool under the hot African sun. They are surprisingly graceful in water, they are good swimmers but they often simply walk or stand on the lake floor or lie in the shallows.
Their eyes and nostrils are located high on their heads, which allows them to see and breathe while mostly submerged. They can close their nostrils and flatten their ears and stay completely submerged underwater for up to five minutes at a time.
At sunset, hippopotamuses leave the water and travel overland to graze. They may travel 10 km in single-file to consume some about 35 kg of grass. Considering their enormous size, a hippo's food intake is relatively low.
Mating and birth can take place on land or in water. Hippo calves weigh nearly 45 kg at birth and can suckle on land or underwater by closing their ears and nostrils.
Few parasites have cornered a market so decisively as Placobdelloides jaegerskioeldi. This unassuming little leech rarely sees the light of day for the very good reason that it lives up a hippopotamus’s arse. Hippos have extremely tough skin and there’s a layer of blubber beneath, so for a leech looking for a blood meal, the rectal region – where the skin is vascular, with blood vessels near the surface – is an ideal place to hang out.
But the leech up the arse is in for a bumpy ride. Hippos are noted for the violence of their bowel movements – they fire out an explosion of slurry and then fling it about with their tails – so the bum leech needs to get a good grip. It has a pair of suckers, front and rear, which provide a firm anchorage, then it drives its proboscis into the rectal wall. Finally, it begins to feed, eventually taking up to ten times its own weight in blood.
There is an eagle in me that wants to soar, and there is a hippopotamus in me that wants to wallow in the mud.
Hippos are among the most dangerous and aggressive of all mammals. Their teeth grow continuously, their canines can reach 50 cm in length. Hippo males use their canines for fighting. To warn off enemies, a hippo may yawn, scoop water with its mouth, shake its head, rear up, lunge, roar, grunt, chase and make a loud wheezing sound, all of which are threat displays. When rival males meet, they stand nose to nose with their mouth open as wide as possible, up to a 150 degree angle. This is called ‘gaping’. Usually the smaller male retreats. When they do decide to fight, they slash out with their tusks or swing their enormous heads like sledgehammers while bellowing loudly. They have been known to die as a result.
A hippo can kill people if it is provoked or feels threatened. Most human fatalities are caused by hippos capsizing boats.
Hippos spray their dung out with huge force. With their tails acting like high-speed propellers, they push their poo out of their back end, flinging it wildly about in a torrent. Millions of tons of hippo dung gets propelled into Africa's rivers each year. Hippo dung brings quite a lot of nutrition into the water with it. For at least part of the year, aquatic fish and invertebrates rely upon hippo dung for their nutritional needs.
According to a story that the San people of Southern Africa tell; when the Creator assigned each animal its place in nature, the hippos wanted to live in the water but were refused out of fear that they might eat all the fish. After begging and pleading, the hippos were finally allowed to live in the water on the condition that they would eat grass instead of fish and would fling their dung so that it can be inspected for fish bones.
Hippos sometimes bask on the shoreline and secrete an oily red substance, which gave rise to the myth that they sweat blood. The liquid is actually a skin moistener and sunblock that may also provide protection against infections.
A fully grown hippo can easily outrun a man.
A group of hippos is called a bloat.
According to The Oxford Companion to Food, the best part of a hippopotamus to eat is their breasts, pot roasted with herbs and spices.
Around 128,000 years ago, hippos lived in the area now covered by Trafalgar Square.
At least one of George Washington's appalling false teeth was made from hippopotamus ivory.
Hippos dispose of crocodiles by biting them in half.
The skin of a hippopotamus weighs a ton.
The oldest-known soup in human history is hippopotamus soup.