Larval forms - Porifera
In the majority of sponges the larval stage develops in the body of the parent. The larva is generally at the blastula stage of development. Figure displays two types of poriferan larval stages, amphiblastula and stereoblastula in which monociliated cells cover the outer surface except the posterior pole.
Figure: Larval forms, Porifera
The interior of the larva generally contains most of the cell types found in the adult except choanocytes. The larva breaks out of the parents' body wall and has a brief free swimming existence.