What’s the Difference Between Oysters and Mussels?

What’s the Difference Between Oysters and Mussels?

Avid readers of Spey (those fabulously pearl-minded, inquisitive darlings) will be quite regularly confronted with words like mollusk, bivalve, oyster and mussel. Indeed, the parlance of pearlers employs a riot of nautical and biological terms that even the most devoted connoisseur of the queen of gems might pause to consider. Such is the pride of the pearl. But even those ravenous souls out for an evening of seafood and Champagne might stop to consider: what’s the difference between oysters and mussels?

Pearls emerge from a most natural process that occurs within certain bivalve mollusks. Together, mollusks comprise nearly a quarter of all marine phyla – truly a stalwart and diverse collection of soft-bodied creatures. Differing as much in size and composition as they do in behavior and environment, the term mollusk might refer to bivalves (like oysters and mussels, our favorites at Spey), the gastropods (snails and slugs), the cephalopods (octopi and squids), and an assortment of other fascinating organisms. But as we whittle down the invertebrate family tree, we come closer and closer to determining the difference between oysters and mussels.

Outwardly, we grant that oysters and mussels are quite similar: ensconced within a bivalve shell, prized for culinary delicacies, fed by filtering the water around them, and capable of producing that most lustrous of organic gems, the pearl. But look more closely. You may notice that mussels have a smooth shell and oysters reside within a rougher covering. If you were to respectfully observe that most intimate moment when oysters and mussels breed (respectively), you would notice that embryonic fertilization differs quiet remarkably, as do the first few weeks of life. And while both are most content to affix to one substrate and live out their days quite peaceably, oysters are more inclined to scuttle to a happier location when the going gets tough. Mussels have a way of never letting go.

Perhaps the most notable difference between oysters and mussels is the habitat in which they reside. Oysters are marine creatures, preferring the saline waters of the ocean to the freshwater lakes and rivers that mussels call home. Mussels may temper a bit of salt in their lives, but rarely venture beyond the brackish water where the river pours into the sea. So there you have it: the difference between oysters and mussels. Just don’t get us started on scallops and clams…

Time for a test: are oysters or mussels featured in the image above?