Thaliacea
Thalicea is a class of marine animals belonging to the Urochordata subphylum. Unlike the ascidians, the members of this group have free life throughout their life cycle. They are known as taliaceae or salps, are pelagic animals in the form of barrel, gelatinous and transparent body, have solitary or colonial forms of several meters, have inhalant siphon and exhalation in opposite positions; hollow and viscera form mass on the ventral surface, water driven by contraction and used in locomotion, breathing and feeding. Many have luminous organs and have alternating generation reproduction.