Kingdom: Animalia (Animals)

The Kingdom Animalia, also called Metazoa, contains a diverse range, estimated to be several million different species, of multicellular, eukaryotic organisms. All animals are motile, meaning they can move spontaneously and independently, at some point in their lives. The body plan of animals eventually becomes fixed as they develop, although some undergo a process of metamorphosis at a certain stage in their lives. All animals are heterotrophs, meaning they rely directly or indirectly on other organisms for their nourishment. Most ingest food and digest it in an internal cavity. Animal cells lack the rigid cell walls that characterize plant cells and most reproduce sexually, by means of differentiated eggs and sperm. Most animals are diploid, meaning that the cells of adults contain two copies of the genetic material.