Figure 9
Representative confocal fluorescence microscopy images and backscatter electron microscopy images highlighting the costae wall and initial skeletal layer development in the lappet-like appendage. (a) A confocal fluorescence image of the lappet-like appendage overlayed with the corresponding SEM image showing the morphology of the lappet-like appendage and its relationship to the costae (Cos), initial basal deposits (InSk) and the basal skeleton (Sk). (b, c) First, the lappet-like appendage deposits an initial skeleton (InSk) via the lappet-like appendage poorly defined calicoblastic extension; then, as the lappet-like appendage moves forward, the trailing calicodermis produces a layer of skeleton (Sk) (arrows show the direction of the thickening), building a stronger basal attachment. The lappet-like appendage can generate rapid accretion deposits (RADs) (b) that form the costae walls (Cos) and further the robustness of the skeleton/attachment. (c) The lappet-like 'appendage's poorly defined calicoblastic extending layer (a) (Ext) appears to produce a protuberance (Prt) in the initial skeleton (InSk). (d) The smooth initial skeleton layer possesses characteristics similar to those of Clypeotheca (Clp) and can form a keystone structure (Key) in a similar fashion to dissepiments, which can indicate irregular development8. CCA; crustose coralline algae, Sub; substrate. calicodermis; Ca, calicodermis extension; Ext, substrate; Sub.
