How Are Oysters Born?
Baby oysters are hatched from tiny eggs. A female oyster can lay as many as 70 million eggs a year. For a few days after oysters hatch from their eggs, they swim about freely.
Then they fasten themselves to a rock or shell, or some other object on the sea bottom, upon which they usually spend the rest of their lives.
They wait for currents to bring their food, and grow about an inch a year until fully grown. Oysters are such a popular food, not only for people but for animals as well, that they probably would have disappeared long ago if they did not lay so many eggs.
Young oysters go through several developmental stages. Fertilized eggs hatch into oyster larvae called trocophores. Only one percent of larvae reach the next stage of development. Those that survive become ‘veligers’ and begin to swim and drift, feeding on tiny plants.
Eventually, the veliger becomes a pedi-veliger, producing a foot-like formation and settling onto a hard, clean patch of the ocean floor (substrate). Once there, the juvenile oyster, called a ‘spat’, attaches itself to the floor with a cement secretion from a gland in the foot.