How do oysters reproduce?

 

If some legends make the oyster an aphrodisiac, one wonders why. In any case, it is not its mode of reproduction that can cause the stir.

No crazy hugs, everything is done remotely and anonymously. A natural Meetic, in a way

The fiercest is the Japanese. The Crassostrea gigas, or hollow oyster, introduced in France in the 1970s, reproduces without knowing the result. When the water temperature reaches around 20 ° C, the female throws her gametes into the water with her valves and the male emits sperm by expelling them with his eyelashes.

Sacred glance! All of this is found in water and produces a larva that first lives on its reserves, then feeds on plankton after five days.

After 15 to 25 days, for the first and last time in her life, she has a foot: she becomes pedivéliger.

This foot will be used to crawl to find the best place to rest and, this done, it secretes a kind of cement to fix the larva and disappears. The larva has become a spat, a baby oyster that will live almost three years in peace before it can be eaten.

The flat oyster (Ostrea edulis, the traditional local oyster, which is hardly any more exploited) has a method which is hardly more fun: the male, always so little passionate, throws his sperm in the water for who wants some, and the female catches them on the fly to impregnate them. Once this is done, it expels the larvae from its shell, where they will experience the same type of development as the Crassostrea.

Sex Change

But what surprises most about this rather neutral reproduction is that oysters can be alternately male and female. Sometimes in the same season, but more often from year to year.

From the spring, when the water reaches 8 to 11 ° C, she takes on the sex that will be hers for the year to come. But we don't know based on what.

We just noticed that the older they get, the more they tend to become female: they are only 30 to 40% in one-year-old oysters and up to 70%, after 3 years.

But there is a final, more unfortunate category of oysters: triploids, which make up 30% of shellfish consumed, are genetically engineered to render them sterile. They thus devote all their energy to growing rather than frolicking, but the breeders are forced to buy spat every year. We don't confuse love with business.

SAISI