The term for animals that eat only plants is "herbivores." These animals have adapted to primarily obtain their energy and nutrients from plant material, including leaves, stems, roots, fruits, and seeds. Herbivores play a crucial role in the ecosystem, as they help to control plant populations and serve as a food source for carnivores (meat-eaters). Many herbivores have specialized digestive systems to process tough plant fibers, including ruminants like cows and deer, which have multiple stomach chambers to efficiently break down cellulose. Examples of other herbivores include rabbits, elephants, and numerous bird species.