preceded_by Platynereis life cycle stage mid trochophore stage late trochophore stage 40-48 lt At a temperature of 18 C this stages lasts from 40.00 hours till 48.00 hours. Developmental stage following Mid-trochophore stage with the following key events: Distinct stomodeal opening surrounded by stomodeal rosette, first chaetae visible within the trunk. Three larval segments appear simultaneously, identifiable by the developing chaetae in the trunk. Macromeres narrower towards the posterior. Second commissure forms in the ventral nerve cord. Dorsal and ventral longitudinal muscles elongate. PdumDv:0000700 platynereis_stage