Explain differance between Subphylum Chaetognatha and Subphylum Urochordata?
Subphylum Chaetognatha: Larval stages of this small group share some of the characteristics with Deuterostomes, but their relationship is not clear. However, these animals do possess the three typical chordate characteristics. The Chaetognaths include the marine arrow worms, which are small distinguished by their lancelet shape and body structure.
Subphylum Urochordata : This small group is known as the tunicates, or "sea squirts." They are characterized by the presence of a cellulose membrane covering that resembles a tunic. Sea squirts are sessile, or attached to marine substrates such as rocks. When stimulated, they shoot a stream of seawater, which gives them their name. Tunicates have chordate characteristics in their larval stages, and only pharyngeal gill slits are present in the adult forms.