preceded_by Platynereis life cycle stage early trochophore stage mid trochophore stage 26-40 mt At a temperature of 18 C this stages lasts from 26.00 hours till 40.00 hours. Developmental stage following Early trochophore stage with the following key events: Free-swimming trochophores showing phototaxis. Increasing amount of shading pigment in the larval eyes. Stomodeal rosette starts forming and moves anteriorly. The body shape starts to change from spherical to conical. Variable: red pigment spots around the prototroch cells. Second cerebral commissure, future nuchal organ nerve and asymmetric axon develop. Three more serotonergic cells around apical ganglion. First commissure in the ventral nerve cord. Dorsal and ventral longitudinal muscles appear. PdumDv:0000600 platynereis_stage