Who thought hippopotamus could be more dangerous than big cats. It is surprising to note that they have killed more than four hundred people in Africa alone. They are otherwise called the “river horse.” They are not only found in rivers and deep waters but also in salt water regions too. They are pure vegetarians. It is the third largest animal on land. They are extremely fast and can even over take a human regardless of its huge size. Their bellowing could be ear splitting. They are very protective of their young ones and their terrain. It could chop off the head of a human from their body with minimal effort. It attacks for safety and not for food. It is closely related to whales and dolphins.