Compared to a carnivore or omnivore, what does a folivore eat?
And the answer: leaves.
While carnivores eat meat and herbivores eat plants, folivores specifically eat the leaves of a plant and stay away from the stem or roots. Some common folivores are the panda, sloth, and koala.
Unlike with fruits, plants don't actually want animals to eat their leaves. Leaves are how plants are able to get their energy from the sun, so plants have evolved to make them pretty darn difficult for animals to eat. Often, leaves are full of toxins, have a bitter taste, are very difficult to chew, and are made of large cellulose molecules that are difficult to break down into usable sugars. Due to these defenses, animals who eat leaves need a lot of specialized traits.
Folivorous mammals have broad teeth with high, sharp cusps connected by shearing crests. These traits allow the folivores to physically break down leaves when chewing (thus the "shear" in "shearing crests"). Folivores then have to chemically break down cellulose molecules into usable energy, so these animals need specialized digestive systems. Some folivores have complex stomachs with multiple compartments, but all leaf eaters have large, long intestines and special gut bacteria that can break up cellulose. Folivores are usually the largest bodied of all mammals and spend a large portion of their day digesting their food, so they are often fairly inactive creatures (see: sloths).
Did you know?
Koalas can eat over two pounds of poisonous eucalyptus leaves every day! Their special fiber-digesting organ, called a caecum, helps to detoxify the chemicals in the leaves. However, they can be quite picky eaters, eating less than 50 of over 700 eucalypt species. Even then, they’ll often choose leaves at the top of the tallest trees that contain more liquid and nutrients.