Fig. 11 in Unusual early development in a cyclostome bryozoan from the Ukrainian Miocene

Fig. 11: Model of larval metamorphosis in the Polupanivka Miocene cyclostome compared with a conventional cyclostome (based on NIELSEN 1970: fig. 2, 1995: fig. 24.3). The ciliated larva (far left) is vertically sectioned to reveal the apical invagination (black) and the invaginated adhesive sac (grey). Normally (top row) during metamorphosis the adhesive sac evaginates to attach the larva to a substrate. However, in the Polupanivka Miocene cyclostome (bottom row), evagination of the adhesive sac apparently occurred while the larva was still floating in the plankton and the adhesive sac no role in attaching the larva to a substrate.