The life cycles of mollusks vary between mollusk families. Some life cycles include a larval stage while others emerge from their eggs as young mollusks with fully developed shells.

Whelks grows as they age, secreting more shell material periodically as they increase in size. Whelks are one such species. Breeding takes place from October to May; thousands of eggs in protective capsules are attached to rocks, shells, and other hard objects. Most of the eggs are used as a source of food for the few developing embryos. After several months, the young, crawling whelks emerge from the capsules.