Q.Which of the chordate characteristics do tunicates retain as adults?

Urochordata or Tunicata (Greek oura, tail) are exclusively marine sea squirts — mostly sessile, though some pelagic, existing solitarily or in colonies. The unsegmented adult body is covered by a protective test/tunic, giving a sac-like adult form.

The coelom is absent, though an atrial cavity surrounds the pharynx. Critically, the notochord is present only in the tail of the free-swimming larva — the origin of the subphylum's name — and is lost once the adult settles. The alimentary canal is complete; circulation is open with a ventral, tubular heart; respiration occurs through pharyngeal gill slits. The dorsal nerve cord, too, is present only in the larva, reduced to a single dorsal ganglion in the sessile a …