
They have huge proportions, which reflect their sedentary lifestyle. The fact is, hippos don’t move around a whole lot. Yep, they’re lazy.
Hippos tend to stay in groups of about fifteen animals, and they have a clear hierarchy there. The older the hippo the more of a social rank it has, and if it’s a male it’s even better.

They weigh 3,300 to 4,000 pounds, or two tons. It’s quite common for them to get larger, and 7,000 pounds is not unheard of for older males. The largest hippo ever recorded was 9,900 pounds (4,500 kg).
The smaller hippos are often called pygmy hippos and they’re a bit more shy, tending to stay in forests. If they ever ran into a larger hippo they’d surely feel cowed, and probably wouldn’t wish to do so again.
All hippos have a squat and bulky body set atop four stumpy legs. To support all their weight the feet have four toes, each with webbing between them, which helps the beast swim and remain upright on land. And they need to stay on land to eat the typical 150 pounds of grass they go through each day.

But they don’t need to – hippos sweat blood. Well, it’s not blood per se, but it’s a viscous red fluid that really starts pouring forth when the animal’s excited.
So they’re hot-blooded, hot-skinned, hot-tempered but no so hot to trot. That’s fine, they don’t much care what others think of them, so happy are they to stick to their groups and wile away the days near their mud holes and rivers. One of the main problems hippos run into involves water, however, and more precisely, the lack of it.

What’s more, when there’s a lack of water in one area there’s often a lack in another. Now different groups of hippos are forced to congregate around ever-diminishing pools of water, and this leads to animosity, bellicosity, and eventually aggression and violence.

These scars come from their large teeth, razor-sharp, and which they aren’t afraid to use. Tusk-like canines mesh with knife-like incisors, the perfect flesh-tearing tools.

It either succeeds or it fails, but either way it’ll leave the battle with more scars than it had going in. Often nothing is accomplished from these fights, but hippos have been persisting in them since the dawn of time.
Sources:
http://www.outtoafrica.nl/animals/enghippo.html