Note
In a brief review of development of the phylum Sipuncula, four patterns of development are recognized: (1) direct with no pelagic stage; (2) one larval stage, a lecithotrophic trochophore; (3) two larval stages, a lecithotrophic trochophore and a lecithotrophic pelagosphera; (4) two larval stages, a lecithotrophic trochophore and a planktotrophic pelagosphera. Larval types and their metamorphoses are described, with special attention to the development and morphology of the larval cuticle.