The 5 Species of Oysters (That You’ll Eat in the US)

There are over 200 species of oysters worldwide, but only 5 are grown commercially in North America and likely to be served to you. (For the more exotic stuff, you’ll just have to do some oyster tourism abroad.)

First, let’s examine the nomenclature of oyster species. Oysters are bivalve (two shell) mollusks in the family Ostreidae. There are two genera, ostrea (flat oysters) and crassostrea (cupped oysters). So you can tell if an oyster is cupped or not by looking at its genus. Of the five species of oysters we have here, 3 are cupped and two are flat.


Pacific (Crassostrea gigas): Originally from Japan, this oyster is now the most important commercial species in the world, making up about 97% of the global oyster production. It’s very hardy, resistant to disease, grows quickly, and can reach lengths of 4-6 inches in 2-4 years. It has a high tolerance to temperature and salinity fluctuations. If left to its own devices, it will keep growing and get very large.

  • Shell: Large cups with a flamboyant ruffled edge. The exterior of the shell is usually coarse and grayish-white, sometimes with purple striations.
  • Meat: The Pacific oyster features a black, velvety mantle on the edge of its meat. (The mantle is the outer rim that an oyster uses to filter food.) The appearance may be jarring at first, but it doesn’t affect the oyster’s taste.
  • Flavor: This varies according to the bay, but usually Pacific oysters have lots of sweet and creamy notes, with a touch of earthiness.


Eastern (Crassostrea virginica): This is the only native East Coast oyster, truly an all-American food. Aside from the Olympia oyster (below), it is the only native oyster to North America, and is found from New Brunswick down to the Gulf of Mexico.

  • Shell: Crescent-shaped, similar to a tear-drop. The shells are relatively smooth and thick, and are somewhat asymmetric in shape.
  • Meat: Tend to be thinner than those of Pacific oysters. Cold water temperatures slow the oyster’s metabolism and produce meats with a slightly crisp texture.
  • Flavor: Varies along the coast, but generally most varieties have a pronounced salty flavor, like biting into the sea. You may also get notes of mushroom, butter and seaweed.


Kumamoto (Crassostrea sikamea): Another immigrant species from Japan’s Kumamoto prefecture, this oyster is very similar to the Pacific oyster but is a separate species. It is a great choice for beginner oyster eaters because of its small size. Like the Pacific oyster, the Kumamoto has a high tolerance for temperature and salinity changes, though it prefers warmer waters and does not spawn in the “cold” waters of the Pacific Northwest.

  • Shell: Small, deep, cup-like shells that are round with widely-spaced wavy ridges on the outer shell. The deep cup usually contains a high ratio of meat to total volume. It takes about three years for Kumamotos to reach market size (2”). Kumamotos do not grow beyond that size, so if you have a Kumamoto that is much larger than that, it may actually be a hybridized Kumamoto/Pacific oyster.
  • Meat: Green-tinged, ivory colored meats that are dense, supple and pillowy
  • Flavor: Sweet, without any fishiness. Often finishes with a melon flavor. Great paired with sparkling wines

European Flat/Belon

European Flat (Ostrea edulis): This species is originally from Europe and doesn’t occur naturally in North America. However, there are self-sustaining wild edulis reefs in Maine now, due to a science experiment gone wrong (or right?). In the 1950s, scientists at the Department of Sea and Shore decided to give away seed for experimental plots of European Flat oysters. They thought the project was a failure, but in the 1980s, a diver going after sea urchins found a large reef of these oysters at the mouth of the New Meadows river. The European Flat had gone feral, and it has been at home in Maine’s waterways ever since. These are the oysters that the ancient Romans and Gauls ate.

Today, the oysters are often marketed as Belon oysters, after their ancestral home in the Belon river and coastal estuaries of Brittany in France. Unfortunately, European flats have a low tolerance to temperature, salinity and environmental fluctuations. They also tend to harbor a protozoa known as bonamia that kills them just as they reach market size. It’s undetectable until the adult oysters start to die. All of this means that European Flat oysters are relatively rare, so if you spot one, you should try it.

  • Shell: Circular with the left valve almost flat, not cupped. The left valve is larger and deeper, with 20-30 ribs and irregular concentric frills. The oyster can reach lengths of 4” in 3-4 years, but may reach a harvestable size in 2 years.
  • Meat: Pale yellowish or greenish in color
  • Flavor: An acquired taste for non-Europeans, but the oyster has a cult following for being bold, brassy and coppery, like sucking on a penny. Beginners may want to opt for something else first.


Olympia (ostrea conchaphila or ostrea lurida [deprecated]): This is the only native West Coast oyster. Once the dominant species in WA, and found from British Columbia to Baja, it is now harvested commercially only in the southern Puget Sound. Like the European Flat, it has a low tolerance for temperature, salinity and environmental fluctuations. Originally, it was grown in diked ponds to protect the oysters from extreme heat or cold. Today, farmers still use a natural set, using a bottom grow-out method and hand-harvesting at low tide.

  • Shell: Relatively flat, round or oval, and generally blackish on the outside, and gray to pale-blue on the inside of the shell. Shells are symmetrical. The Olympia grows very slowly, reaching harvest size in four years, which makes them expensive.
  • Meat: There’s no other way to put it, the meat of an Olympia oyster is tiny. It takes 250 shucked meats to fill a pint container.
  • Flavor: Despite the minute size of the Olympia, the flavor it offers is outsize. Often referred to as a “baby Belon,” the Olympia oyster has an unmistakeable metallic and coppery flavor, with a bit of mustiness and the punch of umami.

Have you tried all five species yet? If so, which is your favorite? If not, keep your eyes peeled at the raw bar and you’ll collect them all soon enough!