It concerns the collect of the larva.
Oyster biology and reproduction
The oyster is a mollusc bivalve ( 2 asymmetrical valves), with lamella branchiae belonging to the filibranchiaes division, to the under-category anysomierous, and to the ostreides family.
Mature oysters operate a sexual reproduction. The Hollow Oysters Crassostrea gigas are oviparous, thus the ovule fecundation with spermatozoon happens in the water influenced by the current. This is an alternative sexuality. Oysters may enjoy the rule of the male or the female and change their sexuality the year after. Some hermaphrodite may subsist after the growing step but it is rare.
From May-June, mature oysters lose their winter lipidic reserve. They replace it by the “milt”. At maturation gonads become inflated by gametic products. This phenomena is due to the climatic movement, warmer water and high salt rate.
Following an external chock, due generally to the temperature movement, a mollusc lays by emitting a pheromone (hormone), inciting the others oysters to do the same. The male gamete (spermatozoids) and female (ovule) fecundate in the ocean. We do speak about external fecundation.
Hatching happens after 24 to 48 hours, the larva begins to secrete its shell. The shell is swimming (pelagic). After 2 or 3 weeks, the foot appears. At this moment the larva begins to seek for a support It is metamorphosing to a “small oyster”, it means a breeding.
Around the 14th of July, the oyster farmer put in place the collectors (the supports). In Marennes-Oleron, collectors may be plastic tub, plastic plate threaded and corded, slate pious, pieces of slate threaded and corded, , pleno ( rectangular support full of plastic).
Slate pieces and plastic tub.
The collectors are used as support for those small oysters which metamorphose when they are fixed.
18 months later, the breeding has grown up on the collector. It is time to detach the small oysters. This operation is called in French “detroquage” Then oysters are named “grattis”.