Noding in Cyprideis torosa and its causes

The ostracod Cyprideis torosa develops nodes on its calcified carapace in brackish waters and is therefore widely used in paleontology as a marker for lower saline waters. The formation of nodes in lower saline waters was investigated with SEM and TEM analyses and micro-cryoscopic measurements of the inner osmoregulation. Noding is considered a failure in osmoregulation, which causes the pillars connecting the inner and outer epidermal cell layer to rupture during the molting process. As a result, the still flexible shell develops protrusions, which then persist as nodes after subsequent calcification.