Stage 30
The Adhesion Stage (CirobuD:0000053) regards the larva attaching to a suitable substrate through its adhesive papillae (24-27 h). The papillae change significantly after adhesion, becoming deflated and sometimes curved. They also start to degenerate. At this stage, the adhesion area is flat. Also called holdfast (Hirano and Nishida, 2000), in the successive stages it will elongate in the stalk (CirobuA:0000632), the epidermal peduncle by which the juvenile is attached to the substratum. The stalk possesses a cavity, derived from the preoral lobe , with its own blood (CirobuA:0000571) circulation.
The two atrial siphons are now in continuity with the atrial cavities. In the juvenile (Stage 41), the siphons will fuse, becoming a single, dorsal atrial siphon. The sensory organs are recognizable within the sensory vesicle but are beginning to degenerate (ot and oc in CIII and Cvi).
The inner and outer compartment of the tunic, with their inner and outer cuticular layer, respectively, are well recognizable (ict and oct, iclt1(C1) and oclt(C2), respectively).