Red Leaf Monkey

Also known as maroon langurs for their auburn coat, these monkeys are native to Borneo, where they spend most of their time in trees munching on the lush jungle foliage, seeds, and flowers, Thomas says.

Their stomachs are actually similar to a cow’s in that they are chambered, allowing them to digest all that fiber they eat.

But unlike the stereotypical monkeys of children’s books, these guys can’t eat bananas or other jungle fruit, as the sugars would wreak havoc on the delicate balance of their complex stomachs.