Function of the Caudal Appendage of Priapulus caudatus

THE caudal appendage of Priapulus consists of a central hollow stalk from which numerous finger-like tubes project. The lumen of the appendage communicates with the voluminous cœlomic cavity by an opening surrounded by circular muscles 1 . Several authors ascribe a respiratory function to the appendage 2,3 , but other theories have also been proposed 4 . The following observations may throw light on the function of the appendage.