Rivers like this one in Kenya, Africa, are dangerous places for animals. Crocodiles inhabit the waters here, stealthily moving in on animals that cross them. A crocodile can take down large animals like zebras or gazelles with ease. They drag them under water and drown them, making them an easy meal. But a full grown hippo is a force to be reckoned with. Hippos have enormous and powerful jaws and they would give even the hungriest crocodile a serious fight. This mother hippopotamus knows that lingering in the water is a hazardous thing, but she and her baby pause to gulp water before finishing their crossing. Aside from rhinoceros' and elephants, hippos are the largest land animals. A female like this one will weigh over 1300kg (2800lbs). They are known to be one of the most dangerous animals in the world. Aggressive and unpredictable, the males claim stretches of river as their territory, defending it from other males and threats with ferocity. Their jaws can open as wide as 180 degrees and their gigantic teeth can deal a fatal wound. While hippos appear to be similar to pigs, they are not closely related. Their closest relatives are whales, dolphins, and porpoises, having diverged from them approximately 60,000,000 years ago. Whales' ancestors were once land dwellers, and much smaller than the whales of today. In this time period, whales evolved rapidly to grow much larger than their ancestors. Their intelligence also increased dramatically in a relatively short period of time as well. Hippos have few predators when full grown. These two will not likely encounter trouble as long as the baby stays close to its mother.