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. Oysters contain high levels of the fatty acid Omega-3, as well as taurin, two of today’s health buzzwords. In 1956, the British government published a report in which their nutritional value was compared to that of milk. Oysters do contain more proteins and carbohydrates and essential vitamins and minerals than milk, but almost none of the fat. 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
  3. The English, the French and the Oyster by Robert Neild.
  4. Oysters by Charles Maurice Yonge.
  5. Seafood: A Connoisseur’s Guide and Cookbook by Alan Davidson.
  6. Oysters: A True Delicacy by Shirly Line.

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: The Belon is the classic gourmet example of Ostrea edulis and for some, the very epitome of oyster eating. The Belon oyster is a native of Brittany.

The Marennes oyster. These well-known slightly-green oysters are raised in “claires”, with a high concentration of the cholorophyll-containing algae Navicula ostrearia. They are grouped as “fines de claires”, which, as per the complicated French system of food classification, means they are the most superior 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: Bluepoint, Long Island. Box Oyster, Long Island. Chesapeake Bay, Chincoteague, Virginia. Cotuit, Nantucket. Kent Island, Maryland. Malpeque, PE Island, Canada. Patuxent, Maryland.

Apalachicola Oytser, Florida: These are sweet, plump and have a slight copper flavor. They have a green-tinged and deep shell. This was probably the oyster that was used for the famous Oysters Rockefeller, a dish created at Antoine’s, in New Orleans during the Gilded Age. The dish was named after John D. Rockefeller, Senior, apparently because they were both so rich.

Breton Sound Oytster, 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 some rare exceptions, regarded as not appropriate for eating uncooked. It can grow to be around 12 inches long, and so is usually considered too large and tough to be eaten 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 of this oyster for serving raw/uncooked include: the Mad River, the Tomales Bay from California and the Totten from Puget Sound in Washington State.

Kumamoto oyster: This variety of the Japanese oyster is often given its own name, the Crassostrea kumamoto. It was first farmed in Japan on the island of Kyushu, and is now frequently farmed in America from the Mexican Gulf to British Columbia. It has a distinctive black shell, full of frills and the meat is lauded as being buttery and delicate.

Crassostrea Angulata

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

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 quite as delicate in taste as the European oyster, and are not generally recommended to be eaten raw. The shells of these oysters have distinct purple lines, and its flesh is also colored with purple at the muscle scar.

Buying and Preparing Oysters

Choosing Oysters

When choosing oysters at a seafood market, your first consideration is that they should be fresh. Secondly, that they do not smell off and if an oyster happens to be open, which it shouldn’t, it should snap shut quickly once tapped with your finger. If an oyster does not shut straight-away, do not buy it. The oysters should also be arranged so that they are laying flat on the ice, not piled up in a haphazard fashion..

The shape of the shell will give you an idea of the amount of meat that the oyster holds. The deeper the cup of the bottom shell, the more meat you will have. The round varieties of oyster, like Belons and Olympias, should be fairly symmetrical. For the more elongated oysters like the Atlantic and Japanese varieties, look for shells that fan out sideways from their hinge. This indicates that the oyster has had plenty of room to grown and develop.

When to Buy What

The best oysters of both the Atlantic and Japanese varieties are usually available all year round. Belons and Olympias do, however, justify the old-fashioned rule about not eating oysters in months without the letter “r” in the name, so you are not likely to find them in markets. This is not because they are dangerous to eat; it is because of differences in the way they reproduce.


Never store oysters in water. If you do not plan to eat them on the same day then arrange them flat on a dish, cover them with a damp cloth or towel, and place them in the refrigerator. This way, they will keep for up to a couple of 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

3 thoughts on “Everything You Wanted To Know About Oysters

  1. great info, thanks. I’m trying (and failing) to find comprehensive nutritional info, specifically of Kumamoto’s…one reference I found said zero carbs, one said 4 carbs in 3 oz… do you know if any such reference? thanks.

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