Hippos spend up to 16 hours a day submerged in water, so it might surprise you to learn that they can't actually swim. Although they have a lot of grace and power when moving through the water, their propulsion cannot actually be considered swimming. You heard us right: Hippos can't swim. Let's check out why.
When a dog jumps into the water, it will propel itself forward by kicking its legs, the whole time keeping its feet off the ground.
By contrast, hippos are not actually capable of keeping themselves afloat just by kicking their legs.
Douglas McCauley, an assistant professor in the department of ecology, evolution and marine biology at the University of California, Santa Barbara, who was interviewed by The Atlantic, explains:
"For all intents and purposes, the hippo does not swim. It almost always maintains some contact with the bottom and walks or bounces off the bottom using these bottom contact points as a source of propulsion."
The below clip of Toronto Zoo's newly named baby pygmy hippo, Penelope, illustrates how a hippo's body is just too dense to be able to swim.
You can see Penelope push off the bottom of her pool, try to stay at the surface by kicking her legs, but then sink back down to the bottom.
Hippos may not technically be able to swim, but they can still propel themselves to the surface when they are in deep water. According to this scientific paper on hippo locomotion, there are periods of time when a hippo is "in flight," meaning it is not touching the surface bottom. The hippo's body is more buoyant in the water, so it can take some dramatic leaps underwater that it could not take on land.
The below clip shows a wild hippo charging at a boat in a river. When it breaks the surface of the water, the hippo seems to be "in flight."
As a human, you may have the ability to swim, while the hippo does not.
But don't think that means you could escape this animal in the water. They are powerful and dangerous; give them respect and plenty of space.