Members of the subphylum Tunicata (or Urochordata) are very common marine animals. The adult tunicates little resemble other members of the phylum Chordata. They lack a backbone and posses only the latter of the three chordate characteristics found in tunicate larvae: a notochord, a dorsal hollow nerve cord and pharyngeal clefts.
This subphylum contains the classes:
- Ascidiacea- Sea-squirts
- Larvacea (Appendicularia)
- Thaliacea- Salps
The Larvacea and Thaliacea are pelagic and are therefore beyond the scope of this work.