![]() Fossilised oyster shells are a common feature of the exposed outcrops of mudstone, sandstone and conglomerate found along the northeast coast some date back 20 million years. This adult oyster is then ready for market. Oysters have been flourishing in New Zealands coastal waters for millions of years. The spat spends around two and a half years growing before it reaches its adult size. The second stage in the process involves the larva attaching itself definitively to its chosen substrate, where it will grow into a spat and, ultimately, an oyster.įollowing this metamorphosis, the larva becomes a micro-spat, then a spat.If the larva is unhappy with the location, it starts swimming again until it finds a suitable place to settle. During the first stage, the larva falls to the bottom to find a suitable substrate.This spot signals the start of metamorphosis, a two-stage process: During this stage, the larva develops a foot as well as a pigmented eye spot on its shell (eyed larva). ![]() The pediveliger larva is the last stage prior to becoming benthic (living on the sea bed). The actual shell begins to form, as well as the hinge which will allow the adult oyster to open and close its valves. The cilia and the velum (which becomes fully formed at this stage) enable it to move through the water. This velum will be fully formed in the veliger larva (the next stage in its cycle). It still has cilia, but it has now acquired a velum to help it move around. It will act as the guide for the shell that will form around it. ![]() ![]() This "D" corresponds to the future oyster shell. The D-stage larva is so called due to its distinctive shape: it looks like the capital letter D. The Trocophore larva is a ciliated larva, which moves by creating a water eddy with its cilia. ![]()
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