The life cycle of Platynereis dumerilii.

The various life stages are depicted and classified based on the worm’s pelagic/benthic behavior. The mentioned time points correspond to those obtained at a thermostated temperature of 18°C [18]. The organism has a diameter of approximately 160 μm from the fertilized egg to 48 hpf. By 72hpf, the swimming larva measures around 250 μm in length. Around 6 dpf, upon starting feeding, it begins elongating through posterior segment addition. Immature worms reach 3–5 cm length. At the end of sexual metamorphosis, the worms become bulkier, contracting longitudinally by almost 50%.