Morphology of the introvert and associated structures of the priapulid Tubiluchus corallicola from Bermuda

A scanning electron microscopical (SEM) and light micro-anatomical study of the anterior abdomen, tubuli, introvert, scalids, buccal tube, peribuccal nerve ring and pharynx of adult Tubiluchus corallicola Land, 1968 (phylum Priapulida) is presented. Where possible, these findings are compared with those of other priapulids and their potential functional properties are discussed. The presence of 25 longitudinal rows of introvert scalids is proposed as one of the few stable external characters of priapulids. The musculature of the bilaterally symmetrical introvert is shown to be of the basic priapulid type. The pectinate teeth of the anterior pharynx are considered to function as detrital rakes or sieves, and the unique pharyngeal musculature of T. corallicola is shown to be a specialized type which could be derived from the more general priapulid form.