There are millions of different animals on this planet, and billions of microorganisms. All life forms--no matter how small or large--have a digestive system, many of which are very different from the human digestive system.
Everything about a sloth is slow-moving, including his digestive system. It can take up to a month for a sloth to process his food.
A cow's stomach is divided into four sections. The first section softens the cow's food, the second section sends the food back up to the mouth where it can be rechewed, the third section removes the moisture from food and the last section mixes the food with digestive juices.
The domesticated pet dog has a digestive system that is fairly similar to a human's. However, the dog's intestinal tract is shorter than a human's, due to the amount of protein dogs consume.
Whales have a three-sectioned stomach. The first section of a whale's stomach breaks down its food by crushing. The second section mixes the food with digestive juices and the third further mixes the food and digestive juices.
A bird's crop acts as a storage compartment for excess food that a bird can't eat at one sitting. Its two-chambered stomach mixes the food with digestive acids and crushes the food thoroughly.