What is the kingdom Animalia explain?
Kingdom Animalia : Kingdom Animalia is separated from the other four kingdoms on the basis of several clearly distinguishing features. The organisms that we call animals eat other organisms. Organisms that have this nutritional mode are referred to as heterotrophs. All members of Kingdom Animalia are multicellular eukaryotes, and most of them are able to move about in search of food, which they ingest. Animals range in size from very tiny microscopic animals to gigantic whales. They live in almost every habitat, and vary widely in terms of structure and function. Animals have evolved tissues, organs, and organ systems that are able to effectively carry out very specialized functions. Most members of Kingdom Animalia reproduce sexually, and the haploid (1N) stage is reduced to the gamete stage in the life history of animals.
Kingdom Animalia is usually grouped into two subkingdoms: Parazoa and Eumetazoa. "Para" means along side, or beside; "zoa" refers to animals. Thus, Parazoa includes those organisms that are next to, or along side the true animals. Eumatazoa is a term that describes later, or more advanced, true animals.
Parazoans are distinct from Eumetazoans in that they do not have any symmetry - or characteristic shape for that matter, and they lack specialized tissues and organs. There is one group (Phylum) that belongs to this subkingdom - the sponges (Porifera).
Eumetazoa then includes all of the other animals - those that do have symmetry (radial or bilateral), definite shapes, and specialized tissues and organs and organ systems to perform specific functions. As such, Eumetazoans are more complex and more advanced than the Parazoans. Eumetazoans in turn are classified according to what type of symmetry they possess: either radial or bilateral. The radially symmetrical organisms include the hydroids, jellyfish, sea anemones, corals, and ctenophores - the comb jellies. All of the other animals have bilateral symmetry.
Another large distinction is made between animals that have backbones (vertebrates) and those that don't have backbones (invertebrates).