A scallop is a marine bivalve mollusk found in all of the world’s oceans. Many scallops are highly prized as a food source. Some scallops are valued for their brightly colored shells.
The name “scallop” originated from the ancient Canaanite sea port Ascalon (modern city of Ashkelon, Israel).
Like the true oysters, scallops have a central adductor muscle, and thus the inside of their shells has a characteristic central scar, marking the point of attachment for this muscle. The adductor muscle of scallops is larger and more developed than that of oysters, because they are active swimmers; scallops are in fact the only migratory bivalve. Their shell shape tends to be highly regular, recalling one archetypal form of a seashell, and because of this pleasing geometric shape, the scallop shell is a common decorative motif.
Most scallops are free-living, but some species can attach to a substrate by a structure called a byssus, or even be cemented to their substrate as adults. A free-living scallop can swim, by rapidly opening and closing its shell. This method of locomotion is also a defense technique, protecting it from threatening predators. Some scallops can make an audible soft popping sound as they flap their shells underwater, leading one seafood vendor to dub them “singing scallops”.