Oysters and mussels are both bivalve molluscs that filter their food from the water, but they hold on differently and reach the table differently. An oyster cements itself to a hard surface; a mussel ties itself down with byssal threads, the "beard" you pull off before cooking. Oysters are the bivalve most often eaten raw, while mussels are steamed or sautéed. Gram for gram, mussels have more than twice the protein, and oysters have more than 20 times the zinc.
This is the companion to oyster vs clam. The short version of the family tree: oysters, clams, mussels, and scallops are all bivalves with a hinged shell.[1]
Oysters vs mussels at a glance
| Eastern oyster | Blue mussel | |
|---|---|---|
| How it stays put | Attached to firm bottom or to other oysters, building reefs | Anchored by byssal threads, the "beard" |
| Foot | None as an adult | A small foot that makes and places the threads; not used for digging |
| Muscles that close the shell | One | Two: a small one at the front and a much larger one at the back |
| Shell | Rough and irregular, one half cupped and one flat, white to gray to tan | Two matching halves, teardrop shaped, black, blue-black, or brown, with a white interior |
| Typical size | 3 to 5 inches | 2 to 4 inches |
| How it is usually eaten | Raw on the half shell, or grilled, fried, or stewed | Steamed or sautéed until the shells open |
| Refrigerator life, live | Up to 7 days | 3 to 4 days |
Sources for the table: NOAA Fisheries species pages, the Chesapeake Bay Program field guide, Lander University's anatomy guides for both animals, Maine Sea Grant, and the Washington State Department of Health.[1][2][3][4][5][6][7]
How their bodies differ
Oysters cement, mussels tie on. Adult oysters stay in one place. They attach to firm bottom and to each other, which is how reefs form.[1] Mussel adults also stay put, but with a different anchor: a cluster of protein threads called the byssus. A gland at the base of the mussel's foot secretes liquid protein, a groove in the foot forms it into threads, and the foot presses each thread onto the surface and lets it harden.[2][5]
The foot. An adult oyster has no foot at all.[4] A mussel has a small, wormlike one. It is not used for digging, as a typical bivalve foot is; its job is making and placing byssal threads.[5]
The muscles. An oyster closes its shell with a single adductor muscle, the one a shucker cuts.[4] A mussel has two, and they are lopsided: the front one is much smaller than the back one, a condition found in all mussels and linked to having a byssus.[5]
The shells. A mussel's two shells are nearly identical mirror images.[5] An oyster's are not: the bottom shell is cupped and the top one is flat, and the outside is rough, in shades of white, gray, and tan.[3] Blue mussel shells are black, blue-black, or brown, teardrop shaped, with fine concentric lines and a white interior.[2]
What they share. Both pump water over their gills and strain out plankton, and neither needs to be fed on a farm.[1][2] Both also release eggs and sperm into the water in enormous numbers. NOAA puts a female blue mussel at 50 to 200 million eggs per spawning event and a female Eastern oyster at over 100 million.[1][2] For more on each, see what oysters eat and how oysters reproduce.
Taste and texture
A raw oyster tastes of salt first, then something sweet, often with a mineral or cucumber note at the end, and it varies a great deal by where it grew. Our article on what oysters taste like covers that, and merroir explains why location matters so much.
NOAA Fisheries describes blue mussels as having tender meat and a sweet flavor.[2] Because mussels are eaten cooked and usually in a broth or sauce, what you taste is as much the pot as the animal. Oysters on the half shell are the opposite case: nothing has been added, so the differences between one variety and the next are the whole point.
How they are eaten
Oysters are opened raw and served on the half shell, or grilled, roasted, fried, and stewed. See raw vs cooked oysters and our shucking guide.
Mussels are cooked in the shell. Maine Sea Grant's instructions are to rinse them under cold water, scrub the shells, pull the beard off toward the hinge, and steam or sauté them for 5 to 7 minutes until the shells open fully and the meat is plump and opaque.[6] There is no knife work.
The checks before and after cooking are the same for both. Throw out any with cracked or broken shells and any that stay open when tapped, and after cooking in the shell, throw out any that did not open.[8] Our guide to how to clean oysters covers the scrubbing step for oysters.
Mussels also keep for less time. Washington's health department gives live oysters up to seven days in the refrigerator and names mussels as an exception at three to four days.[7] See how to store oysters for the method.
On safety, official advice does not separate the two. The FDA tells people at higher risk of foodborne illness to avoid raw or undercooked shellfish, and names raw oysters specifically.[8] NOAA notes that the Vibrio bacteria that occur naturally in seawater can cause illness from raw or undercooked shellfish, mussels included.[2] Our guide to Vibrio and raw oyster safety covers the risk in detail.
Nutrition: oysters vs mussels
These are USDA FoodData Central figures for raw meat, per 100 grams (about 3.5 ounces).[9][10]
| Per 100 g, raw | Eastern oyster (farmed) | Blue mussel |
|---|---|---|
| Calories | 59 kcal | 86 kcal |
| Protein | 5.2 g | 11.9 g |
| Fat | 1.6 g | 2.2 g |
| Carbohydrate | 5.5 g | 3.7 g |
| Sodium | 178 mg | 286 mg |
| Zinc | 37.9 mg | 1.6 mg |
| Iron | 5.8 mg | 4.0 mg |
| Manganese | 0.39 mg | 3.4 mg |
| Selenium | 63.7 mcg | 44.8 mcg |
| Vitamin B12 | 16.2 mcg | 12.0 mcg |
| Omega-3 (EPA + DHA) | 0.39 g | 0.44 g |
What stands out:
- Protein. Mussels have more than twice as much per 100 grams.
- Zinc. Oysters have more than 20 times as much. The FDA's Daily Value for zinc is 11 mg, so 100 grams of oysters is more than three days' worth.[11]
- Manganese. Mussels are the high one here: 3.4 mg per 100 grams against a Daily Value of 2.3 mg.[11]
- Vitamin B12. Both are very high. The Daily Value is 2.4 mcg, so 100 grams of either covers it several times over.[11]
- Omega-3s. About the same.
For the full picture on oysters, including who should limit them, see are oysters good for you.
How they are farmed
Both are farmed without feed, because both filter their own food from the water.[1][2]
Farmed mussels are grown off the bottom, in the water column, on longlines (ropes), on rafts, or by the bouchot method, which uses ropes wrapped around poles.[2] Maine Sea Grant describes young mussels being "seeded" onto ropes hung from rafts, or grown on the ocean bottom.[6]
Oysters are grown directly on the bottom or in mesh bags, trays, or cages that sit in the water column or float.[1] Our article on how oysters are farmed goes through the methods.
Shellfish allergy
Oysters and mussels are both molluscs, not crustaceans, and US allergen labeling law treats the two groups differently. If allergy is the reason you are comparing them, read are oysters shellfish and talk to your allergist.
Frequently Asked Questions
Are oysters and mussels the same thing?
No. Both are bivalve molluscs that filter feed, but they are different animals. Oysters attach directly to hard surfaces and have rough, uneven shells. Mussels anchor themselves with byssal threads and have smooth, dark, matching shells.
What is the difference between oysters and mussels?
How they attach, how they look, and how they are eaten. An oyster has one shell-closing muscle and no foot, and it is the bivalve most often eaten raw. A mussel has two shell-closing muscles, a small foot that spins its beard, and is cooked in the shell.
Do mussels taste like oysters?
Not much. NOAA Fisheries describes mussels as tender and sweet, and they are usually eaten cooked, often in a broth or sauce. Raw oysters are briny first and vary widely from one growing area to the next.
Which has more protein, oysters or mussels?
Mussels. USDA figures give raw blue mussels 11.9 grams of protein per 100 grams and raw farmed Eastern oysters 5.2 grams. Oysters lead on zinc by a wide margin: 37.9 mg against 1.6 mg.
What is the beard on a mussel?
It is the byssus, a bundle of protein threads the mussel makes with its foot to anchor itself. Pull it off toward the hinge of the shell before cooking.
Do you clean mussels and oysters the same way?
Mostly. Both are rinsed under cold water and scrubbed, and both are checked for cracked shells and for shells that will not close. Mussels need the extra step of removing the beard.
Sources