Seed Oysters

Oysters are hermaphrodites that inhabit eutrophic intertidal zones.

Oviparous oyster species release sperm and egg cells directly into the sea where fertilization occurs externally, forming the free swimming eyed larvae that eventually settle on a clutch to grow into an adult oyster. They show sequential hermaphroditism whereby sex is determined by a genetic and environmental factors like age, size, water temperature, food availability and population density. Environmental cues trigger mass spawning events, leading to milky clouds of numerous eggs drifting in the water that cross fertilize with sperm into a planktonic larval stage .
Higher temperatures, sufficient food and larger size tend to induce the female phase. A larger proportion of female oysters are found in older and larger populations.

Larviparous oyster species internally brood their fertilized eggs and release well developed, feeding larvae into relatively less turbid, deeper, clearer waters. These oyster are males in early stages of sexual maturity, then change into females but can switch back and fro throughout their lives.

These filter feeding oyster spat from different genera need to be alimented with phytoplankton, microscopic algae and zooplankton through water currents that also provide dissolved oxygen, allowing them to grow into market size and restore habitats.