Phyla occur in the Protist, Moneran and animal kingdoms; these groups contain organisms like protozoa, bacteria, chordates and annelids. The animal kingdom has the largest number of phyla, followed by the Protist and Moneran kingdoms, respectively. The organisms in these phyla share biological and physical traits that distinguish them from other members of their groups.
In the animal kingdom, all organisms with backbones belong to the chordate Phylum. These species include aquatic and land animals, such as fish, reptiles, mammals, amphibians and birds. The arthropod Phylum contains animals that have jointed legs and exoskeletons. Many insects, including beetles, grasshoppers and bees, belong to this group. Other phyla in this kingdom contain mollusks and annelids. Mollusks are soft-bodied organisms that, sometimes, have hard shells; prominent members include octopus, squids, clams, oysters, slugs and snails. The annelid Phylum includes segmented worms, namely earthworms and leeches. The animal kingdom also contains the echinoderm Phylum, which contains spiny animals with multiple radiating arms, such as starfish and sea urchins. The Protist kingdom includes two phyla: protozoa and euglenophyta. Both contain tiny, microscopic organisms including amoeba, sporozoa and euglena. The Moneran kingdom includes two phyla as well, which are bacteria and cyanobacteria. Bacteria may be malignant or benign while cyanobacteria are generally harmless.