Characteristics of animal kingdom

Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and usually multicellular(although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile,if only at certain life stages. In most animals, embryos pass through a blastula stage, which is a characteristic exclusive to animals.