The question of what fish scallops come from is based on a common misunderstanding of marine biology. Scallops are not fish; they do not originate from any finned creature. These popular seafood items belong to an entirely different kingdom of life. The confusion stems from the fact that both groups are harvested from the ocean and categorized together as “seafood.”
The True Biological Identity of Scallops
Scallops are invertebrates, meaning they lack a backbone, which immediately separates them from all fish. They belong to the Phylum Mollusca, a diverse group that includes squid, snails, and octopuses. Within this phylum, scallops are classified in the Class Bivalvia alongside clams, mussels, and oysters. Bivalves are characterized by having two hinged shells, or valves, made of calcium carbonate.
In contrast, fish are vertebrates belonging to the Phylum Chordata, typically possessing fins and a skeletal structure. Scallops are grouped into the family Pectinidae, consisting of over 300 species found across the world’s oceans. Many species are among the few free-living bivalves, meaning they are not permanently attached to the seabed like most oysters or mussels. This active lifestyle is possible due to a highly specialized muscle, which is the part most people recognize as the scallop itself.
Unique Anatomy and Physical Features
The edible portion of the scallop is the large adductor muscle, responsible for opening and rapidly closing the two fan-shaped shells. This muscle has two distinct parts: a striated (fast) section used for sudden movement, and a smooth (slow) section used to keep the shells tightly shut. Rapid contraction forces water out near the hinge, creating jet propulsion that allows the scallop to “swim” erratically to escape predators like starfish. This powerful function explains why the adductor muscle is larger and more developed than those found in stationary bivalves.
Along the edge of the scallop’s mantle are up to 200 tiny, bright blue eyes. These eyes are complex, featuring a lens and a mirror made of guanine crystals that reflects light onto a double-layered retina. This structure allows the scallop to detect movement and changes in light, helping it spot potential threats. Scallops are also filter feeders, using their gills to strain plankton and organic material from the water.
Habitat and Commercial Harvesting
Scallops inhabit marine environments across the globe, ranging from the low tide line to depths of over 100 meters. They typically settle on soft substrates like sandy, gravel, or mud bottoms, forming dense groupings known as beds. Commercially important species include the large Atlantic sea scallop, found from the Mid-Atlantic to Canada, and the smaller bay scallop, which lives closer to shore in bays and estuaries.
The primary method for collecting wild scallops is through specially designed scallop dredges or bottom trawls towed along the seabed. In shallower coastal areas, they are also harvested by divers or through smaller-scale methods. Most commercial vessels process the catch immediately, shucking the scallop to remove the adductor muscle and discarding the rest of the animal at sea. Aquaculture, or farming, is also a growing source of scallops, particularly in countries like China and Japan, helping to meet global demand.