The hippopotamus is the third-largest living land mammal, after elephants and white rhinos. With the absence of sweat glands, hippos spend most of the day submerged in water, using both water or mud to stay cool. The large hippo is an aggressive animal: old scars and fresh, deep wounds are signs of daily fights that are accompanied by much bellowing, neighing and snorting. Amazingly agile for their bulk, hippos are good climbers and can traverse steep banks each night to graze on grass. They exit and enter the water at the same spots and graze for four to five hours each night in loop patterns, covering one or two miles , with sometimes up to five miles. Their modest appetites are due to their sedentary life, which does not require high outputs of energy. A single young hippos is born either on land or in shallow water. In water the mother helps the newborn to the surface, later teaching it to swim. Newly born hippos are relatively small, weighing from 55 to 120 pounds , and are protected by their mothers , not only from crocodiles and lions but from male hippos that can attack while in the water. A young hippo begins to eat grass at 3 weeks, but its mother continues to suckle it for about a year. Newborns often climb onto their mother’s backs to rest.