Larval Cycle of a

Pearl Oyster (family Pteriidae)

Pearl oysters spawn when there is a marked environmental temperature change (either an increase or drop will do). This temperature change triggers the spawning mechanism of those animals that are sexually ripe (this usually happens at an age of 2 years).

The male will begin spawning, and this added stimuli will make the female do the same. The male's sperm will make their way until they find the female's unfertilized eggs and will fertilize them. After this event, the fertilized eggs will begin cellular subdivision until they grow into a small larvae (usually known as the trochophera larval stage). Later stages are recognized by the appearance of more "mature" or recognizable body parts: the shell, the abductor muscle, the mantle and the foot.

The larval cycle:

1)  Trocopheral stage (size of 50 microns); 2) D-type larva (70 microns); 3 to 5) umbo stage larva (100 to 225 microns); 6) "crawling" spat stage (250 microns); and 7) Young Spat (1 mm).

The entire larval cycle will last around 25-36 days until, at last, they attain the status of a fledgling "spat" (still invisible to the naked eye). Finally, the little oyster will grow to a size of 1 to 3 mm and finally it will be given the name of "pearl oyster spat". These are ready to be harvested off the bags.

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Last Updated 05/2007

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