All the families of rodents eat a wide range of foods. Most rodents are herbivorous, plant eaters, eating a wide range of plant materials, including seeds, stems, leaves, roots, and flowers. Many of these species eat primarily seeds. Some species, such as the grasshopper mouse, eat insects and spiders. Other species, such as the Australian water rat, are primarily carnivorous (meat-eating), preying (eating animals for food) on small fish, frogs, and mollusks. Many are to some degree omnivorous, eating both plants and animals. Still others have highly specialized meals, eating only a few species of invertebrates, animals without a backbone, or fungi.