Kingdom Plantae & Kingdom Animalia

Before there were three, four, and now the five kingdoms, the entire living world was divided into either "animal" or "vegetable." There are still hangovers from the two-kingdom system. These include treating members of the fungal kingdom as "non-green plants," and bacteria and cyanobacteria as "single-celled plants." In the present five-kingdom system, animals and plants are more narrowly defined than with the older systems.


Animals are multicellular, complex (i.e., have a high degree of differentiation), heterotrophic eukaryotes with cells that do not have cell walls. Examples include sponges, flatworms, round-worms, leeches, clams, starfish, insects, fish, frogs, lizards, birds, and our own group, the mammals. Mammals, the group with which we probably are most familiar, include among others, mice, rats, monkeys, and humans.


Plants are complex, multicellular organisms that are photosynthetic autotrophs: They produce their own complex foods from carbon dioxide and water through photosynthesis. Cells of plants have plastids (including chloroplasts), vacuoles, and cell walls that contain cellulose.