preceded_by Platynereis life cycle stage protrochophore stage early trochophore stage 24-26 et At a temperature of 18 C this stages lasts from 24.00 hours till 26.00 hours. Developmental stage following Protrochophore stage with the following key events: Hatching larvae actively swimming in the water column, but yet without phototaxis. First pigment appears in the larval eyes. Telotroch forms apical ganglion forms. One serotonergic cell in the brain. First larval brain axon. Prototroch nerve develops. Ventral nerve cord is v-shaped. PdumDv:0000500 platynereis_stage