Genetics- The phylum Mollusca includes such a broad range of animals, there is no single way that all reproduce: it varies. All Mollusks produce eggs. In sexual reproduction, the Gonads (organs found in Mollusks) shed ova or sperm into the Coelom, a cavity that surrounds the heart. After the gametes are in this cavity, nephridia (other organs) extract them, and bring them to the mantle cavity. Mollusks that use sexual reproduction and go through processes like this rely on external fertilization. There are other Mollusks that reproduce completely alone, which is called Asexual reproduction. Those that reproduce Asexually use internal fertilization, or are Hermaphrodites.
Mollusks are created using two components, similar to Humans: sperm and egg, so life starts when an egg is combined with sperm.
-Having an egg fertilized is the first stage of Mollusk development -The next stage is the Trochophore stage, where the egg becomes a free swimming larva -Now the Mollusk is in early Veliger stage, where it later develops into a Veliger.