Is a Scallop Considered a Shellfish? Unpacking this Seafood Classification

December 21, 2025 •

2 min read

Over 8,000 species of marine and freshwater bivalves exist, a diverse class of mollusks that includes the popular scallop. This often-debated seafood is indeed considered a shellfish, though it is not a crustacean and belongs to a different family entirely. Understanding this specific classification is key for both culinary enthusiasts and those with shellfish allergies.

Quick Summary

Yes, a scallop is considered a shellfish, specifically a bivalve mollusk. It is related to clams and oysters but biologically distinct from crustaceans like shrimp or lobster. This article breaks down the classifications, explores their culinary uses, and discusses implications for people with allergies.

Key Points

Scallops are Shellfish: The term 'shellfish' is a broad culinary category, and scallops definitely fit within it.
Scallops are Mollusks: Biologically, a scallop is classified as a mollusk, not a crustacean like shrimp or crab.
Scallops are Bivalves: More specifically, scallops are bivalve mollusks, which means they have two hinged shells, just like clams and oysters.
Scallops Can Swim: Unlike most other bivalves, scallops can swim short distances by rapidly clapping their shells together using their powerful adductor muscle.
Allergy Considerations are Important: While distinct from crustacean allergies, those with mollusk allergies or high sensitivity should be aware of potential cross-reactivity.
Cooked Tender: The delicious edible part of a scallop is the adductor muscle, prized for its sweet, buttery flavor and tender texture when properly cooked.

Demystifying the Shellfish Category: Mollusks vs. Crustaceans

Shellfish is a culinary term for aquatic invertebrates with a shell or exoskeleton, not a strict biological classification. It primarily includes two groups: mollusks and crustaceans. Crustaceans, like crabs and shrimp, are arthropods with jointed legs and exoskeletons. Mollusks are soft-bodied and may or may not have shells. Bivalve mollusks are a subgroup that includes clams, oysters, mussels, and scallops.

The Bivalve Mollusk: A Scallop's True Identity

Scallops are classified as bivalve mollusks, recognized by their two-part, hinged shell. Unlike many sedentary bivalves, scallops can swim using their strong adductor muscle to clap their shells, which is the main edible part.

Comparing Scallops to Other Shellfish


Feature	Scallops	Crustaceans (Shrimp, Crab)	Other Bivalves (Oysters, Clams)
Biological Phylum	Mollusca	Arthropoda	Mollusca
Key Characteristic	Free-swimming bivalve	Jointed legs, hard exoskeleton	Sedentary or burrowing bivalve
Edible Part	Adductor muscle	Tail and claw/leg meat	Entire soft-bodied animal
Texture	Tender, buttery	Meaty, firmer	Soft, slimy (oysters) or chewy (clams)
Flavor Profile	Mild, sweet, briny	Rich, savory, sometimes sweet	Briny, mineral-forward
Allergy Risk	Generally lower risk than crustaceans, but cross-reactivity is possible	High risk due to protein tropomyosin	Potential allergy, but distinct from crustacean allergens

Culinary Insights: Preparing and Cooking Scallops

Scallops are valued for their sweet flavor and tender texture, best achieved with brief cooking. Popular methods include pan-searing for a caramel crust, bacon-wrapping as an appetizer, using bay scallops in ceviche, or grilling larger sea scallops.

The Importance of Labeling and Allergy Awareness

Distinguishing between mollusk and crustacean is crucial for those with shellfish allergies. Crustacean allergies are more frequent due to the protein tropomyosin. While many with crustacean allergies can eat mollusks, cross-reactivity is possible, and consulting an allergist is advised. U.S. law requires labeling for crustacean shellfish but not mollusks, necessitating careful attention.

Conclusion

In conclusion, a scallop is considered a shellfish, specifically a bivalve mollusk, distinct from crustaceans like crab or shrimp. Its classification highlights its two-part shell and unique swimming ability. Understanding these biological and culinary differences is important for preparation and vital for managing food allergies. For further information on bivalves, refer to the National Ocean Service website [https://oceanservice.noaa.gov/facts/bivalve.html].

Frequently Asked Questions

Scallops are not fish or crustaceans. They are mollusks, which are biologically different from both. While both are considered seafood, fish are vertebrates with backbones, and crustaceans are arthropods with exoskeletons and jointed legs.

Mollusks are soft-bodied invertebrates like scallops, clams, and squid, often with shells. Crustaceans are a separate group of arthropods characterized by jointed legs and an exoskeleton, including shrimp, crabs, and lobsters.

Many people with a crustacean allergy can safely eat mollusks like scallops. However, cross-reactivity is possible, so it's best to consult an allergist before consuming scallops if you have any shellfish allergy.

The large, round adductor muscle is the most commonly eaten part. Other parts, such as the reproductive organ (roe), are also edible and consumed in many parts of the world, though they are often discarded in the United States.

The terms 'wet' and 'dry' refer to how scallops are processed after harvesting. 'Wet' scallops are soaked in a phosphate solution, which preserves moisture but can negatively impact flavor and searing. 'Dry' scallops are untreated and are preferred by chefs for better caramelization and taste.

Bay scallops are smaller, sweeter, and more delicate, harvested from shallow waters closer to shore. Sea scallops are larger, meatier, and harvested from deeper ocean waters.

Fresh scallops should be creamy white or pale in color, have a firm and not excessively slimy texture, and smell faintly briny, never strongly fishy or like sulfur.