Vestibule and rudiment formation in C. subdepressus larvae.

A Vestibule invagination 5 dpf (arrow). B Detail of vestibule reaching the left coelomic sac. C Fusion of vestibule and left coelom (arrow). D Posterior region of a competent pluteus larva showing a well-developed rudiment (dashed line). Appendages (podia and spines – arrowheads) are present and active; developing rudiment occupied most of the body and displaced the larval gut (s). Scale bars =  (A, D); (B, C)