"Platynereis dumerilii" trochophore and metatrochophore larvae are positively phototactic. A pair of primitive kidneys of trochophore are absent in tornaria. The lifecycle of these snails start off as embryos that develop into planktonic trochophore larvae. It is produced following either the embryonic or trochophore larval stage of development. Fertilized eggs hatch into free-swimming trochophore larvae. Egg develops into the trochophore, preveliger, veliger, and to the juvenile. After fertilisation, the embryos develop into trochophore larvae. Veligers hatch from egg capsules or develop from an earlier, free-swimming trochophore larval stage. The pre-oral coelom of tornaria is absent in trochophore. The fertilized eggs develop into trochophore larvae, which live as plankton. The preanal ciliated ring of trochophore corresponds with principal ciliated ring of tornaria. These two groups have long been considered close relatives because they share trochophore larvae. The trochophore larvae depend on their internal yolk supply for energy. Trochophore larvae are often planktotrophic; that is, they feed on other plankton species. The most common form of larval developmental plan for polychaetes is the trochophore larvae.