Phylum (plural: phyla) is a taxon used in the scientific classification of life. "Phyla" is adopted from the Greek phylai, the clan-based voting groups in Greek city-states. Phyla represent the largest generally accepted groupings of animals and other living things with certain evolutionary traits, although the phyla themselves may sometimes be grouped into superphyla (e.g. Ecdysozoa with eight phyla, including arthropods and roundworms; and Deuterostomia with the echinoderms, chordates, hemichordates and arrow worms). Informally, phyla can be thought of as grouping animals based on general body plan, e.g., having bones vs. having an exoskeleton. This is morphological grouping. But despite the seemingly different external appearances of organisms, they are classified into phyla based on th