In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum.
The taxonomic rank of "subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used the rank of subphylum, for instance monocotyledons as a subphylum of phylum Angiospermae and vertebrates as a subphylum of phylum Chordata.
The dorsal nerve cord is an anatomical feature found in all chordates, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates. It is one of the five embryonic features unique to all chordates, the other four being a notochord, a post-anal tail, an endostyle, and pharyngeal slits.
All chordates (vertebrates, tunicates and cephalochordates) have dorsal hollow nerve cords.
Anthozoa is one of the three subphyla of Cnidaria, along with Medusozoa and Endocnidozoa. It includes sessile marine invertebrates and invertebrates of brackish water, such as sea anemones, stony corals, soft corals and sea pens. Almost all adult anthozoans are attached to the seabed, while their larvae can disperse as plankton. The basic unit of the adult is the polyp, an individual animal consisting of a cylindrical column topped by a disc with a central mouth surrounded by tentacles. Sea anemones are mostly solitary, but the majority of corals are colonial, being formed by the budding of new polyps from an original, founding individual. Colonies of stony corals are strengthened by mainly aragonite and other materials, and can take various massive, plate-like, bushy or leafy forms.
Members of Anthozoa possess cnidocytes, a feature shared among other cnidarians such as the jellyfish, box jellies and parasitic Myxozoa and Polypodiozoa. The two classes of Anthozoa are class Hexacorallia, with members that have six-fold symmetry such as stony corals, sea anemones, tube anemones and zoanthids, and class Octocorallia, with members that have eight-fold symmetry, such as soft corals, gorgonians (sea pens, sea fans and sea whips), and sea pansies. Some additional species are also included as incertae sedis until their exact taxonomic position can be ascertained.