Aggregates form double-row chains in the form of a tight spiral coil.
Since the direction of swimming is at a right angle to the axis of the chain, Pegea swims slower than species of Salpa , in which the chain axis and direction of swimming are aligned. Zooids have distinctly cylindrical bodies with soft tests, length from 6 to 12 cm. Of the two species of Pegea that can be found on the West Coast, P. socia is more likely to be seen north of central California. It is distinguished from P. confoederata by its gold-colored pigmentation. Solitary individuals of both species have more plump bodies, with lengths up to 14 cm.