Five different species of oysters are cultivated in North America; a handful more are cultivated around the world. Each has its own look, flavor, and style.
The Eastern oyster (Crassostrea virginica) is native to the Gulf of Mexico, the Atlantic coast of North America, and nowhere else. It tends to have a strong, gray-brown shell and a clean, briny flavor.
The Olympia oyster (Ostrea lurida) is native to the Pacific coast of North America. It stays very small, has beautiful, round, pearlescent shells, and a strong flavor of mushrooms and celery salt. It was overharvested in the 1800s and is now grown by just a few folks in the Pacific Northwest.
The Pacific oyster (Crassostrea gigas) is native to Japan’s Pacific coast. It grows quickly and easily; has elegant, ruffled shells with streaks of pink and purple amid the white and green; and tends to be sweeter and less briny than the Eastern oyster, with a flavor like cucumber and melon rind. It was imported in the 1930s to save the west coast industry after the Olympia was nearly wiped out, and is the main oyster used today worldwide, from France to China.
The Kumamoto (Crassostrea sikamea) is a little cousin of the Pacific oyster, native to the far southwestern tip of Japan. It stays small and deep-cupped compared to the Pacific, and tends to be very sweet. It’s many people’s favorite oyster.
The European Flat (Ostrea edulis), also known as a Belon, is the native oyster of Europe. It’s related to the Olympia, but has a much larger size and an even stronger flavor of smoke and metal. Love it or leave it. It’s hard to cultivate, and is thus usually harvested wild. Best places to still find it are Brittany, Ireland, and Maine.
The New Zealand Flat (Ostrea chilensis) is native to New Zealand and Chile. Closely related to the European Flat, it is even more potent. It’s still harvested wild in southern New Zealand, where it’s generally referred to as the New Zealand Bluff oyster, but it’s also being farmed and sold in New Zealand and the United States as a Kiwa.
The Sydney Rock Oyster (Saccostrea glomerata) is native to Australia, where it’s still found in small numbers. Deep cupped and sweet, it closely resembles a Kumamoto or small Pacific.