Nutrition
Hippos are herbivores and eat only short grass, mainly during night when the temperate is cooler. They can eat an average of 45 kg of grass a day (about 100 pounds) which is only around 1.5% of their total body weight. Although they have 36 teeth, they chew not with their teeth, but with their lips. The incisors that can see and the canines, get to be 18 inches long. Those are used primarily for defending their young and establishing a territory.
Hippos have complete circulatory and digestive systems. They have a three-chambered stomach that includes the parietal blind sac, the stomach, and the glandular stomach. Fermentation of microbes takes place in the stomach. Then, enzymes are used to catalyze digestion in the small and large intestines. They have slow metabolic rates. Since they only eat grass, it is necessary for them to conserve energy. The reason we can see them so well is that a hippo can open his mouth 180 degrees, in comparison to a human that can only open 45 degrees. During the day they stay in groups, but at night when they are forging for food, the are solitary.
