Types of Shellfish: 16 Kinds With USDA Values and FDA Facts

Types of shellfish fall into two groups in USDA SR Legacy names, crustaceans and mollusks, and FDA handles the two differently for allergen labeling. This guide ranks 16 cooked shellfish entries from USDA data by protein per 3 ounces, with sodium, iron, zinc and vitamin B12 and the FDA percent Daily Value, and adds the FDA and EPA mercury chart and CDC’s advice on raw oysters. For the other types of seafood, see our sibling guide to types of fish.

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Types of shellfish: crustaceans and mollusks

The Dietary Guidelines for Americans, from USDA and HHS, describe seafood as a protein foods subgroup that “includes fish and shellfish.” USDA SR Legacy begins each shellfish name with its group: the shrimp, crab, lobster and crayfish entries start with Crustaceans, and the oyster, clam, mussel, scallop, octopus, cuttlefish and whelk entries start with Mollusks. FDA’s allergen rules use the same two groups, and the FDA and EPA mercury chart covers shellfish under the word fish.

Squid also sits in the FDA and EPA lowest-mercury category, but SR Legacy lists cooked squid only fried, so it is not in the USDA tables here; see squid. Mussels, octopus, cuttlefish and whelk do not appear on FDA’s chart. The Dietary Guidelines add that methylmercury is found in seafood in varying levels.

Shellfish ranked by protein in USDA data

The table lists USDA FoodData Central SR Legacy entries for shellfish cooked with moist heat or steamed, at 3 ounces (85 grams), ranked by protein. The percent Daily Value (%DV) uses the FDA Daily Values of 2,300 milligrams for sodium, 18 milligrams for iron, 11 milligrams for zinc and 2.4 micrograms for B12; protein has no %DV here because the FDA labeling rule bases a protein %DV on an amount corrected for protein quality.

In USDA data, cooked whelk lists about 40.5 grams of protein per 3 ounces, the most in this table, followed by cuttlefish at 27.6 grams and octopus at 25.3 grams. Among more familiar shellfish, USDA lists spiny lobster at 22.4 grams, clams at 21.7 grams, blue mussels at 20.2 grams and shrimp at 19.4 grams, while the eastern entry for oysters lists 9.7 grams.

The mollusks lead for iron and B12. Cuttlefish, octopus and whelk list 8.1 to 9.2 milligrams of iron per 3 ounces in USDA data, and both oyster entries list 7.8 milligrams, 43% of the FDA Daily Value. USDA lists the eastern oyster at about 66.8 milligrams of zinc per 3 ounces and the Pacific oyster at 28.3 milligrams, and the clam entry at 84.1 micrograms of B12, 3,502% of the FDA Daily Value. Among crustaceans, USDA lists Alaska king crab at 6.5 milligrams of zinc and the spiny type of lobster at 6.2 milligrams. See also foods high in zinc and foods high in iron.

Sodium varies widely in USDA data: the clam entry lists about 1,022 milligrams per 3 ounces, Alaska king crab 911 milligrams and shrimp 805 milligrams, against 82 milligrams for farmed crayfish. USDA notes that its cooked shrimp entry may contain additives to retain moisture. The Nutrition Facts label on a package is the figure for that product; see also low sodium foods.

Shellfish allergen labeling

FDA lists crustacean shellfish, “like crab, lobster, and shrimp,” among the nine major food allergens, and its allergen guidance (Edition 5, January 2025, nonbinding) says molluscan shellfish “(such as oysters, clams, mussels, or scallops) are not.” FDA says the law requires the species of crustacean shellfish to be declared, so a label cannot simply say shellfish. That is a labeling rule, not a statement about any person’s allergy; FDA’s rules do not replace an allergist’s advice about a specific shellfish.

Raw and undercooked shellfish

CDC says Vibrio are bacteria that naturally live in certain coastal waters, and that “most people get vibriosis by eating raw or undercooked shellfish, particularly oysters.” CDC adds that Vibrio “can concentrate inside oysters and other seafood that live in these waters,” and CDC’s advice is plain: “Do not eat raw or undercooked oysters or other seafood. Cook them before eating.” CDC also says not to let raw seafood, its drippings or its juices contaminate other foods, and to wash hands with soap and water after handling raw shellfish.

Other types of seafood

Our single-food guides cover scallops, crawfish, abalone, sea urchin and sea cucumber, and our sushi guide covers that dish. USDA SR Legacy also keeps separate wild and farmed entries for crayfish and eastern oysters, so a figure from one entry does not describe the others.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Types of Fish: 23 Fish With USDA Values and the FDA Mercury Chart, Shrimp Nutrition: Protein, Calories and Is Shrimp Healthy?, Oysters: USDA Nutrition, Zinc, Raw Oyster Safety and Who Should Skip Them, Crab Nutrition: Calories, Protein and Imitation Crab Facts, Types of Crab: NOAA Crab Species and 6 USDA Crab Entries, Types of Shrimp: 5 NOAA Shrimp Species and USDA Values.