I eat vegetarian 99% of the time, but I cannot and will not ever travel back home to the east coast and not toss back some seafood. Shellfish have become my favorite type of seafood in recent years, and I’ve learned quite a bit about bivalves, such as the fact that they are likely the most sustainable and ethical non-plant based food source available to us. I have also learned about the differences among bivalves (partially through delicious personal experience), in particular oysters vs. clams — my two favorites.
The Science
As someone who studies biology, it did not surprise me to find out that the terms “oyster” and “clam” are actually just umbrella terms for groups of similar but distinct species. The oysters we eat belong to the family Ostreidae and are different from the commercial pearl producing oysters of the Pteriidae family. Some common species consumed include Crassostrea virginica, known as Eastern Oysters, Crassostrea gigas, known as Pacific Oysters, and Ostrea lurida/conchapila, known as Olympia Oysters.
"Clam" is an even more ambiguous term than oyster as clams can belong to a variety of families. The quintessential edible clam, i.e., the classic raw bar littlenecks and the namesake of New England clam chowder, is Mercenaria mercenaria, known semi-formally as Quahog clams and informally as Atlantic Hard Shell Clams. However, there are other familiar edible clam species including Mya arenaria, fondly known as steamers and Venerupis philippinarum, commonly known as Manila clams.
The Taste
Nearly all types of oysters and clams that I have tried have the characteristic fresh, salty taste of bivalves, but I find oysters to be more buttery and smooth while clams maintain a more pungent, briny taste — a difference that is especially pronounced especially on the half shell.
Nutrition
Nutritionally, these two bivalves are excellent for you. Oysters are low in fat and calories, comparatively high in protein, and rich in phosphorus, calcium, potassium, zinc, and vitamin B-12.
Clams are also a low fat, low calorie, and high protein food, but bring large amounts of iron, selenium, manganese, phosphorus, vitamin C, and a ludicrous amount of vitamin B-12 to the table.
Ways to Enjoy
Nutrition is important and all, but more importantly, oysters and clams are tasty, versatile foods that can be used in a variety of ways. Though I personally feel that the best way to consume oysters is raw with a little Mignonette sauce and fresh lemon juice (can you tell that I like my food tangy?), they are often also consumed fried, baked, grilled or even as a shooter with tequila or vodka. Nevertheless, oysters generally maintain their status as the star of the dish (drink?).
Clams on the other hand are often a component of a more complex dish, such as in New England clam chowder (Manhattan clam chowder is a myth), linguine with clam sauce, or Spanish paella.
There is so much to love about oysters and clams, from their sustainability to their stellar nutritional marks to their nostalgic, beachy taste. They both have unique qualities and strengths, but the next time you find yourself at a seafood restaurant or raw bar you should not be considering whether to order oysters vs. clams, but rather how many oysters and how many clams.