Phlebobranchia is a suborder of sea squirts in the order Enterogona

Enterogona

Enterogona is an order of tunicates in the class Ascidiacea. It describes a group of marine animals....

. The group includes both colonial and solitary animals. They are distinguished from other sea squirts by the presence of longitudinal vessels in the pharyngeal basket and by the gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...

s being surrounded by a loop of gut. The posterior part of the abdomen is absent, and many species also lack the epicardial cavity that surrounds the heart and other internal organs in many other sea squirts.