The larvae of oysters, such as the eastern oyster, cement their mantles to rocks, shells, or any other solid objects and spend their lives in one place, opening their growing shells to filter algae from the water.
The oysters change their sex during their lives, starting as males and usually ending as females. The shape of oysters varies and depends mainly on how many crowd about them in the bed as they develop.
Types of Oysters
There are two basic types of oysters in the world, flat oysters and cupped oysters. Let’s talk about the oysters you are most likely to see in markets or be offered in restaurants.
The two most common flat oysters you may have heard about are Olympia oysters (our native California oyster) and Belon oysters. The Belon is also called the European flat oyster. While the Belon is native to Western Europe, it has been grown by a few farms in America, first on the east coast and then on the west coast. This oyster does not have a very long shelf life and is offered mostly around the Christmas holidays. The oyster is high in minerals such as Iron and is famous for pairings with wines, since it affects your palate in a way that allows you to taste more of the nuances of the wine. In blind tastings with the Olympia, most people could not tell the difference, meaning these two oysters are very similar in taste. The Belon oyster is very symmetrically round (and flat) while the Olympia is more rectangular. Olympia oysters are produced commercially in southern Puget Sound only. The Olympia is the oyster you hear about in ‘Hang town Fry” recipes of the gold rush days. Both oysters can be ordered specially from your fishmonger, with the Olympia being more easily to get then the Belon.
There are SO many species of cupped oysters (well over 100) from many countries. The US produces two species of cupped oysters, the east coast oyster and the west coast or Pacific oyster. You hear MANY names for these oysters and these are regional names. The eastern oyster goes by the names (from North to South): Malpeque, Canada; Wellfleet, Boston; Blue Point; New York; Assateague, Lower Chesapeake Bay; Chincateague, Upper Chesapeake Bay; Indian River; Florida (Atlantic Ocean); Gulf oysters, New Orleans and oysters from Texas. There are four species of oysters found in Japan. Two species are grown on the west coast: the Myagi oyster and the Kumamoto oyster. The majority of “Pacific” oysters being sold are Myagis and can ranch in size from an x-small (2 to 3 inches long) to a large (6 to 9 inches long). I recommend small oysters for the half shell and medium oysters for the bbq. Really big oysters are (ironically) the least expensive and I think they are good for chowders, stuffing in turkeys and (maybe) the bbq.
In general, Myagi oysters have a more pronounced flavor then eastern oyster. Your taste and preparation method will determine if this is “good or bad”. You will see oysters from New Zealand in the US; they are a type of Myagi. You may eat “Portuguese “ oysters in Europe (a version of the Myagi) or “rock oysters” when you are down under in Australia, New Zealand or South Africa. The rock oysters are really tasty and compare to our Kumamoto. Finally, people ask me bout pearl oysters. There are many types of flat oysters that produce pearls. My favorite pearls come from northern Australia or the Islands around Tahiti and are dark in color. By the way, those places that guarantee a pearl in your oyster can say that because pearl farmers x-ray the oyster before opening it. They can tell from the x-ray if he pearl is of commercial gem quality. What do they do if the pearl is not of gem quality – they sell it to American tourists in ocean tourist traps?
Pearls are an organic gem, created when an oyster covers a foreign object with beautiful layers of nacre. Long ago, pearls were important financial assets, comparable in price to real estate, as thousands of oysters had to be searched for only one pearl. They were rare because they were created only by chance.
Today pearls are cultured by man: shell beads are placed inside an oyster and the oyster is returned to the water. When the pearls are later harvested, the oyster has covered the bead with layers of nacre. Most cultured pearls are produced in Japan. In the warmer waters of the South Pacific, larger oysters produce South Sea cultured pearls and Tahitian black cultured pearls, which are larger in size. Freshwater pearls are cultured in freshwater mussels, mostly in China.
The quality of pearls is judged by the orient, which is the soft iridescence caused by the refraction of light by the layers of nacre, and luster, the reflectivity and shine of the surface. Fine pearls do not have any flaws or spots in the nacre: it has an even smooth texture. Other factors which affect value are the regularity of the shape, size, and color: rose tints are the most favored.
Cultured pearls and natural pearls can be distinguished from imitation pearls by a very simple test. Take the pearl and rub it (gently!) against the edge of a tooth. Cultured and natural pearls will feel slightly rough, like fine sandpaper, because of the texture of natural nacre. Imitations will feel as smooth as glass because the surface is molded or painted on a smooth bead.