Oysters - Everything You Need To Know

Everything You Wanted To Know About Oysters

Introduction to Oysters

There was a time when oysters flourished, when they were enjoyed in staggering quantities by rich and poor alike, but these days, the oyster is a luxury. It must be kept safe from pollution, parasites, and marine predators in order to preserve it for human consumption — the pinnacle of which is the raw, living oyster (with all due respect to the many who adore their oysters cooked). In Consider the Oyster, the inimitable M.F.K. Fisher identifies three types of oyster eaters: “loose-minded sports” (who will jump at any opportunity at all), those who like them raw (the most extreme of whom can’t even abide a tiny drop of lemon juice on their oysters), and those who like them cooked.

The Joy of Oysters According to Tolstoy

“The Tatar waiter rushed off, his coat tails flying; in five minutes he returned with a plate covered with oysters in their pearly shells, and a bottle.

Oblonsky opened his starched napkin and tucked it into his waistcoat, settled his arms comfortably, and began on the oysters.

“Not too bad,” he said, lifting the quivering oysters from their pearly shells with a little silver fork, and swallowing them one after another. “Not too bad,” he repeated, glancing with soft glittering eyes at Levin, then at the Tatar waiter.

Levin did eat his oysters, though he would have preferred bread and cheese. But he enjoyed watching Oblonsky. Even the Tatar waiter, who had drawn the cork and poured the foaming wine into tall thin wine glasses, straightened his tie and glanced at Oblonsky with an obvious smile of pleasure.

“You don’t care for oysters?” asked Oblonsky, as he drained his glass. “Or are you thinking of something else, hm?”

From Anna Karenina, by Leo Tolstoy (New American Library, 1988).

The Oyster in History

Oysters thrive in areas where salt water and fresh water meet — estuaries, salt marshes fed by rivers and streams, coastal waters — the same places where people have always tended to settle. Huge, ancient mounds of oyster shells have been found in such areas all over the world, indicating that they have long been a popular source of nourishment.

The ancient Greeks are known to have eaten them, and when the Romans invaded Britain in 55 BCE, and sampled the delicate harvests of the British coastal waters, they, too were smitten with the craving for oysters. Live oysters were transported to Rome – at great expense. Soon, oyster farms were established, in order that they might be served in almost unbelievable profusion at banquets — a single diner might consume more than six dozen. But oysters were not reserved for the wealthy.

Throughout the centuries, along the coasts of Europe, oysters were popular, accessible to the masses, and eaten with gusto. When Europeans landed in the Americas, they found the native people of the New World had their own immense supplies of oysters — and their own a centuries-old habit of consuming them in huge quantities. This must have been a pleasant reminder of home to many of the settlers.


Maguelonne Toussaint-Samat, in her book, History of Food, points out that the presence of oysters in ancient Greek society may be detected in the word “ostracism.” In the early sixth century BCE, the Athenian statesman Cleisthenes instituted a constitution for Athens. Included in this was a process intended to prevent the possibility of tyranny, in which the governing body would vote to remove undesirable persons — that is, those who had the potential to become tyrants — from its midst.

Once a year, at a meeting convened for the purpose, each person present would write the name of his candidate for exile on an oyster shell (ostrakon), and when the results were tallied, if any man garnered enough votes, he was sent out of the region for ten years. Eventually, clay shards took the place of the shells, and the period of exile was shortened to five years.

Oyster as Aphrodisiac

In the 17th century, still life paintings testify to a fascination with the unusual beauty and sensuous appeal of the oyster. And in his memoirs, written in the early 18th century, Casanova attributed his legendary prowess to his habit of consuming several dozen a day. (Perhaps the passionate fondness they evoke was responsible, by transference, for their reputation as an aphrodisiac. Or, maybe it was the other way around.)

The Lean Years

By the mid-18th century, though, the oyster population in many parts of the world had begun to show the effects of such unbridled enjoyment. The French government deployed the navy to protect their endangered oyster beds. Although the oyster was still known as nourishment for the poor in England as late as the Victorian era, by the turn of the century, this perception had changed. Everywhere, oysters became scarce where once they were plentiful. Oyster gatherers learned oyster farming in order to continue their livelihoods, and, although this saved oysters from disappearing, it marked the end of their widespread availability as economical food. When M.F.K. Fisher was writing in the 1940s, it was still common to buy raw oysters by the dozen, but today they are often sold by the piece — to a public as eager and adoring as ever.

Oysters Nutrients

Raw oysters were once considered to be particularly good for invalids, and with good reason, it turns out. They are high in Omega-3 fatty acid as well as taurin, two of today’s health buzzwords. And in 1956, the British government released a report in which their nutritional value is compared to — and exceeds — that of milk. Oysters contain more proteins and carbohydrates than milk, essential minerals and vitamins, but almost none of the fat for which milk is famous. Gulping down a dozen oysters will set the dieter back fewer than 100 calories, on average

Oysters on the Web:

  1. Mystic Oyster Farmers: Mystic Oysters
  2. The Spruce Eats Oyster Varieties — a good picture chart of shells and description of varieties
  3. Safety considerations to keep in mind when eating raw oysters.

Oyster Reading List:

  1. Consider the Oyster by M.F.K. Fisher (San Francisco: North Point Press, 1988). It would be misleading to mention this 76-page book as if it were simply a source of information about oysters. As with so much of Fisher’s work, it is part essay, part memoir, part cookbook, with a great deal of poetry mixed in. Even people who don’t have much fondness for oysters should probably read it — they might change their minds.
  2. A History of Food by Maguelonne Toussaint-Samat, translated from the French by Anthea Bell (Cambridge, MA: Blackwell Publishers, 1992).
  3. The English, the French and the Oyster by Robert Neild. London: Quiller Press, 1992.
  4. Oysters by Charles Maurice Yonge. London: Collins, 1960.
  5. Seafood: A Connoisseur’s Guide and Cookbook by Alan Davidson (New York: Simon and Schuster, 1989).
  6. Oysters: A True Delicacy by Shirly Line (New York: MacMillan, 1995).

Eating Oysters on the Half Shell

The oysters are served on the bottom, or deeper, shell in order to reserve the “liquor,” the liquid which the oyster releases to surround itself when it is removed from the water. For many, drinking the liquor immediately after swallowing the oyster is the ultimate chaser.

The oyster inspires love among its devotees, but it seems that no ardor is greater than that felt by an oyster-loving inhabitant of an oyster-growing area for the local oysters, served raw.

Blue Points? Welfleets?

On the whole, we only eat about five species of the creature, and only three of those species are consistently considered good enough to serve on the half shell. The only thing that differentiates oysters of the same species – and, as every oyster lover will tell you, they do definitely differ – is the environment in which the oysters were raised. How high is the mineral content in the water? What sorts of micro-scopic marine creatures live there? How high is the salt content? What is the water temperature? These are the things that matter. The impact of these variables explains why oysters are almost always named after the places where they grew up, and why there is such a wide variety to choose from at raw bars.

Qualities of Oysters

The qualities of a raw oyster are usually described in terms of three elements: texture, degree of sweetness/salinity, and mineral/marine plant life flavor. Traditionally, oysters are presented six to a plate, arranged on the lower shell around a piece of lemon. Strategies for adding condiments vary. For some, any addition to the oyster is heresy; for others, a drop of lemon, a little mignonette sauce, a hint of black pepper, or a dab of hot sauce (this especially in Louisiana) is ideal. One particularly luxurious condiment strategy is a drop or two of Pernod followed by the tiniest dab of caviar. Restraint in condiment use is crucial, though, because the flavor of the oyster is easily overwhelmed.

Drinks with Oysters

Feelings also run high in the matter of which alcoholic beverages best accompany a meal of oysters. Many agree that the flavor of the drink can obscure the taste of the oyster, and that the drinking should be done afterwards, or that an oyster cracker or two should follow a sip before the next oyster is eaten. The Irish traditionally opt for stout or a glass of black velvet (a mixture of stout and champagne). Champagne, in itself, is a popular recommendation, as are very dry white wines, say a Chablis or Muscadet.

Types of Oysters

Ostrea Edulis

The Belon is the most well known of these oysters. They are round, symmetrical, expensive, and always flavorful. They should never be cooked. They will not be available in markets during the summer (the non-R months) because this is the time when the oysters spawn, causing the texture to become gritty and the flavor to diminish.
Also called: European oyster, flat oyster
In England: Dorset, Whitstable
In America: they have been successfully cultivated, especially in Blue Hill (Maine) and in the Pacific Northwest
In France: Belon — the classic example of Ostrea edulis and, for some, the epitome of oyster eating. The Belon is native to Brittany. Marennes — the famous green-tinged oysters are raised in claires, with a high concentration of the cholorophyll-containing diatom Navicula ostrearia (a tiny algae). They are grouped as fines de claires, which, according to the rather complicated French system of classification, means they are designated as the most superior in quality of oysters.

Ostrea Lurida

It seems that the only known type of Ostrea Lurida is the Olympia, an oyster that is native to the Pacific Northwest of the United States, and that is mostly associated with the waters of Puget Sound in Washington State. It is a very tiny oyster — on average about the size of a quarter, certainly never larger than two inches in diameter.

It takes up to five years to mature, a relatively long time. The flavor is renowned for being good and strong, with a pleasant aftertaste. Again, this oyster is too fine to be used for cooking. As with the European oyster, the Olympia spawns over the summer and changes in texture, making it less desirable during those months.

Crassostrea Virginica

This is the species that most American oyster lovers call their own. They thrive all the way up to Prince Edward Island and down into the Gulf of Mexico, so the variation among oysters of the different regions is quite great. In general, northern oysters are considered to be firmer, somewhat better for eating raw than the southern varieties. This difference is attributed to the colder climate of the north.

Correspondingly, though they are safe to eat year round, some people do consider the softer texture and blander flavor of the oysters (even northern ones) in the summer to be less appetizing than during the “R-months.”

Also called: Atlantic oyster, Eastern oyster
Regional names (just a few of many): Bluepoint (Long Island), Box Oyster (Long Island), Chesapeake Bay, Chincoteague (Virginia), Cotuit (Nantucket), Kent Island (Maryland), Malpeque (PE Island, Canada), Patuxent (Maryland)

Apalachicola (Florida) — Plump and sweet, with a hint of copper flavor, these oysters have a greenish, deep shell. This may have been the oyster that was used for Oysters Rockefeller, a dish created at the New Orleans restaurant, Antoine’s, during the Gilded Age. It was named after John D. Rockefeller, Sr., because they were both so “rich.”

Breton Sound (Louisiana) — These gulf oysters grow wild in the reefs of Louisiana. They vary in saltiness according to the season, becoming sweetest in the spring when the marshes are flooded with fresh water.

Wellfleet (Massachusetts) — The salt marshes of Wellfleet in Cape Cod, fed as they are by springs, are the perfect environment for raising oysters. Although the oysters native to the region were depleted by the settlers there in the late 18th century, the area was quickly and successfully restocked with oysters from nearby areas and has remained a strong producer ever since.

Crassostrea Gigas

This oyster is, with a few exceptions, regarded as inferior for eating raw. It can grow to be 12 inches long, and is therefore often simply too large and tough to be good on the half shell. It adapts well to different environments and is widely cultivated outside of Japan, mostly on the West coast of the US.
Also called: Pacific Oyster, Japanese Oyster

Popular varieties for serving raw include: Mad River and Tomales Bay (California) and Totten (Puget Sound, Washington)

Kumamoto oyster: This variation of the Japanese oyster is sometimes given its own species name, Crassostrea kumamoto. It was originally cultured on the island of Kyushu in Japan and is now raised in America from the Gulf of Mexico to British Columbia. It has a distinctive, frilly black shell, and the meat is praised as being delicate, even buttery.

Crassostrea Angulata

Also known as the Portuguese oyster, they are native to the coastal waters of Spain and Portugal. By an accident of history, they are now widely cultivated in Brittany, where they help to support oyster farmers who might otherwise have to rely solely on the European oyster, which can be much more difficult to grow.

In 1868, a ship loaded with Portuguese oyster spat was forced to weather out a storm in the Bay of Biscay and, afterwards, dumped its cargo, figuring that it was all dead or dying. Enough of the little oysters lived to create a thriving population. They are not as refined in taste as the European oyster, and are not usually recommended to be served raw. The shells of the oysters have distinctive purple streaks, and its flesh is tinged with purple at the muscle scar.

Buying and Preparing Oysters

Choosing Oysters

When choosing oysters at the market, the primary consideration is that they be fresh, they do not smell and if one is open (which it shouldn’t be) it should snap shut emphatically once tapped. If an oyster doesn’t close immediately, don’t buy it. The oysters should be arranged so that they are lying flat, not piled willy-nilly.

The shape of the shells will give you a good idea of the amount of meat you are getting. The deeper the cup of the lower shell, the better. The rounder varieties of oysters, such as Belons and Olympias, should be symmetrical. For the more elongated Atlantic and Japanese oysters, look for shells that fan out widely from the hinge, indicating that the oysters have had plenty of room to develop.

When to Buy What

Good oysters of the Atlantic and Japanese varieties are available year-round. Belons and Olympias do, in a way, justify the old rule about not eating oysters in months without the letter “r” in the name, so you are unlikely to find them in markets. This is not because they are dangerous; it is the result of differences in the way they reproduce.


Do not store the oysters in water. If you do not plan to eat them right away, arrange them flat on a tray, cover them with a damp towel, and store them in the refrigerator. They’ll keep this way for one or two days.

Shucking Oysters

It can be difficult to shuck an oyster, mostly because both the oyster and the shucking knife require a fair amount of brute strength to master, but the idea is simple.

The oyster is held with the deep shell down, to preserve as much of the liquor as possible. Then the knife (which is unlike a kitchen knife, in that it has a blunt tip and a much stiffer blade) is slipped between the shells so that they can be pried open. The muscles attaching the meat to the upper and lower shells are then cut, so that the oyster can be removed with a fork.

Some people hold the oyster in the hand while shucking; others set it on a flat surface. Some people approach the task by first cutting through the hinge; others pry it open from the other side. If you want to, you can always have the fish monger do this job for you.

There are easier, tidier methods (which die-hards would call cheating) for opening your oysters, however. Putting the oysters in the freezer for two or three hours, and then allowing them to return to room temperature will cause them to open by themselves, as will placing them in the microwave for about 20 seconds.

Both of these methods kill the oysters, so it is important to serve or cook them immediately.

A Natural History of Oysters

The oysters we eat belong to two genera, Ostrea and Crassostrea, which differ not only in appearance (Ostrea are rounder, more like scallop shells, and Crassostrea are elongated and asymmetrical) but also in their styles of hermaphrodism.

Oyster Reproduction: Au Naturel


Members of the genus Ostrea are bisexual, that is, they alternate between being male and female during the course of a single breeding season. During a female phase, the oyster deposits eggs within the shell, and these eggs are fertilized by sperm released when the same oyster switches to a male phase. After a 12-day period of incubation, the larval oysters, or spat, swim away from the parent in search of their own place to settle.


Members of genus Crassostrea are intersexual. They begin life as males, and then change to females the following season. After this, they remain primarily female but revert from time to time into males. Reproduction is quite a bit more haphazard for this genus, because the eggs and sperm are released directly into the water, and fertilization takes place when a pair happens to cross paths. Successfully fertilized eggs, should they survive, rapidly grow into spat, and they, too, swim off in search of a home.

After fourteen days, the spat, whether Ostrea or Crassostrea, must attach themselves to a stationary object – a rock, a mangrove tree, the post of a pier, even another oyster. There they will remain for their entire lives — unless they happen to be cultured oysters, in which case, the spat has settled on a collector planted there by an oyster farmer.

Oyster Reproduction on the Farm

Various methods are used to farm oysters. In America, a popular method for raising oysters is to suspend them in mesh bags to protect them from the predators lurking in the sediment below. The bags are inspected occasionally, until the oysters are large enough to harvest.

In France, special lime-coated tiles are used as collectors. Once encrusted with small seed oysters, the tiles are moved to special basins, or parks, where the oysters are scraped off and placed in a sheltered habitat, to be cosseted until they are ready to be taken to market, usually at three to four years old — their flavor begins to diminish once they reach the age of five. (By contrast, a really lucky oyster — one who manages to survive unmolested by humans, starfish, or the oyster drill snail, one who escapes infestation — could live up to 50 years.)

An Oyster Ranch
Picture “Oyster Ranch” by the measure of mike

Preferred Oysters

The most sought-after, most expensive oysters, those classified as fines de claires, are produced by raising the native European oyster (Ostrea edulis) in claires, specially converted salt marshes, where the water is frequently changed and is higher in mineral content. The special ingredient in this water is the tiny organism, Navicula ostrearia, which, because it contains chlorophyll, imparts a distinctive — and much admired — green tinge to the oysters.

Things That Go Bump on the Oyster

The oyster, in spite of its tough-looking shell, is vulnerable to quite a few marine creatures. Oyster drill snails and sea urchins get at the soft meat by boring through the shell; starfish achieve the same by wrapping themselves around the shells and wrenching them open; octopuses can crack the shells with their beaks. Oysters are also vulnerable to parasites, which often thrive best in the sheltered environments of the oyster farms.

The Pearl

Many members of the oyster family will produce a pearl when a foreign object gets inside the shell and irritates the sensitive flesh. But the pearl that threatens to crack the tooth of the patron of a raw bar will, at best, resemble a tiny bit of gravel. Luminous, iridescent pearls — the valuable ones — are produced by a different kind of mollusk.

Photo by the measure of mike

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