Video narration
Digestion is how animals turn food into usable nutrients, and separate out waste. It starts at the mouth, where food is bitten or gathered and mixed with saliva to begin breaking it down. Next, the esophagus is a muscular tube that pushes the food along to the stomach. In the stomach, strong mixing and acids—or other digestive fluids, depending on the animal—break food into a soupy mixture. Then the food enters the intestines. This is where most nutrient absorption happens: tiny surfaces pull proteins, sugars, fats, vitamins, and water into the body. What can’t be used moves on, becomes waste, and is eliminated through the end of the digestive tract. Different animals have different shapes and helpers, but the goal is the same: take in food, absorb nutrients, and remove leftovers.