UNLIKE OTHER MEMBERS OF THE BIVALVE FAMILY, SCALLOPS CAN FLY. And flying scallops make for an amazing sight!
Well, actually scallops swim, by jetting along underwater, as shown in this awesome video from East Coast Divers, my old dive shop in Brookline, Mass.
NEITHER A BURROWER NOR AN ATTACHER BE
Like other bivalves – clams, oysters and mussels – scallops share the basic anatomical structures of other members of Phylum Mollusca. As members of Family Bivalvia, they do so with laterally compressed bodies enclosed in two-part shells of saucer-shaped valves, or sides. With gracefully scalloped edges, of course.
Unlike other bivalves, scallops don’t bury themselves in the seafloor (clams), glue themselves to a hard substrate (oysters) or attach themselves to a surface with strong byssal threads (mussels). Okay: A very few species of scallops cement themselves to a surface, oyster-wise.
WHY FLYING SCALLOPS SWIM
Overwhelmingly, most of the 250 species of scallops worldwide live unattached on the seafloor, free to do their flying scallops act when necessary.
It’s necessary to evade predators, like starfish, lobsters, crab, turtles and some, mostly bottom-dwelling, fishes like cod, flounders and wolffish.
HOW FLYING SCALLOPS SWIM
Scallops do it by clapping their valves together, rapidly opening and closing their two-part shells. As the Encyclopedia of Life puts it, “everything about their characteristic shell shape— its symmetry, narrowness, smooth and/ or grooved surface, small flexible hinge, powerful adductor muscle, and continuous and uniformly curved edge— facilitates such activity.”
SWIMMING AND JUMPING
They can move forward – that is, “swim” – by rapidly drawing in water through the through the space between their valves and forcing it out through small holes near the hinge. They can move backwards – that is, “jump” – by ejecting the water through the gape between the valves with which it was taken in.
Jumping usually means landing on the sea bottom between each jet burst. Swimming generally let them travel farther on multiple bursts. Although “farther usually means about 16 feet/5 meters. By and large, after fur or five bursts the flying scallops are exhausted and need to rest.
PRINCIPAL SOURCES: Marine Biology, Fourth Edition, Peter Castro, Michael Huber; Marine Life of the North Atlantic, Andrew Martinez; “Pectinidae – Scallops,” Encyclopedia of Life; “Atlantic Sea Scallop, Placopecten magellanicus,” NOAA; “Crazy Scallops” Video, East Coast Divers.