1) Category 2) Class 3) Class larvacea 4) Family 
==Biology== The appendicularian body shape resembles that of the tadpole-like larvae of most tunicates. Like a common tunicate larva, the adult appendicularian form has a discrete trunk and tail. Evolution by retaining juvenile traits as an adult is known as neoteny. Like most tunicates, appendicularians feed by drawing particulate food matter int...
[n] - small free-swimming tunicates
A group of planktonic tunicates that secrete a gelatinous house, used to strain unsuitable particles (large particles are rejected). An inner filter apparatus of the house, the so-called food trap or particle-collecting apparatus, is used to retain food particles. 
class Larvacea noun small free-swimming tunicates; sometimes classified as an order