A member of the subphylum Tunicata of the phylum Chordate
(see chordate). Tunicates are known commonly
as sea squirts. They are marine and have sac-shaped bodies
with two openings, a mouth and an atrial port. Water is sucked in through
the mouth, filtered for food particles, and passed out through the atrial
port. Many tunicates, however, have a larva that is free-swimming and exhibits
all the characteristics of chordates.