Chordates are animals which are either vertebrates or one of several closely related invertebrates. They are united by having,
for at least some period of their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and
a post-anal tail. The phylum Chordata consists of three subphyla: Urochordata, represented by tunicates; Cephalochordata,
represented by lancelets; and Craniata, which includes Vertebrata.
Echinoderm" there are seven main classes of Echinoderms which are brittle stars, basket stars, sea urchins, sand dollars,
sea lilies, feather stars, and sea cucumbers. They can be found at every ocean depth, from the intertidal zone to the abyssal
zone.
Hemichordata is a phylum of worm-shaped marine deuterostome animals, generally considered the sister group of the echinoderms.
They date back to the Lower or Middle Cambrian and include an important class of fossils called graptolites, most of which
became extinct in the Carboniferous.
Vetulicolia is an extinct phylum encompassing several Cambrian organisms. Their bodies comprise two parts; their front is
voluminous and is tipped with a large "mouth" and a row of five round to oval-shaped features on each side which have been
interpreted as gills - or at least openings in the vicinity of the pharynx. Their posterior section comprises seven segments.
They lack preserved appendages of any kind. The area where the anterior and posterior parts join is constricted.
Protacanthopterygii is a taxon superorder of bony ray-finned fish. Protacanthopterygii is composed of primitive teleosts.
Their common fish anatomy usually include: lack of specialization; greater than 24 vertebrae; adipose fin; mesocoracoid bone;
glossohyal teeth; non-protrusible upper jaw; proethmoid and several perichondral ethmoid bones commissural fibers; one supraorbital
foramen and no gular plate.
