10 Facts About Scallops

Learn About the Seafood Sensation, Scallops

You may have eaten a scallop, but do you know exactly what you were eating? You also may have found a brightly-colored scallop shell on the beach. What are scallops? Here you can learn more about this popular seafood, including 10 fun facts about where scallops live, how big they get, and how they feed and reproduce.

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Scallops are animals.

The eyes of a Bay scallop
Stephen Frink/Photodisc/Getty Images

Although they may not look like it, scallops are animals. They are in the Phylum Mollusca, a group of animals that also includes snails, sea slugs, octopuses, squid, clams, mussels, and oysters. 

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Scallops are bivalves.

Open scallop
Vincenzo Lombardo/Photographer's Choice RF/Getty Images

Scallops are in the group of mollusks called the bivalves. These animals have two hinged shells that are formed of calcium carbonate. Bivalves like scallops are threatened by ocean acidification, which affects the ability of these organisms ​to build strong shells.

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Scallops can swim.

Swimming scallop
Mark Webster/Oxford Scientific/Getty Images

You almost have to see it to believe it. Unlike other bivalves like mussels and clams, most scallops are free-swimming. They swim by clapping their shells quickly, which moves a jet of water past the shell hinge, propelling the scallop forward. Click here to see a video of a swimming scallop. Scallops are surprisingly quick when they move. 

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Scallops have easily-recognizable shells.

Scallop shells / Dr DAD (Daniel A D'Auria MD), Flickr
Dr DAD (Daniel A D'Auria MD) / Flickr / CC BY-SA 2.0

When you think of the term "sea shell," a scallop shell might instantly come to mind. Scallops have fan-shaped shells, often with ridges or ribs. At the bottom of the shell, there are two auricles, or "ears."

Scallop shells are an emblem of St. James, who was a fisherman in Galilea before becoming an apostle. James is said to be buried at Santiago de Compostela in Spain, which became a shrine and pilgrimage site. Scallop shells mark the Road to Santiago and pilgrims often wear or carry scallop shells. 

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Scallops have eyes.

Close up of Spiny Pink Scallop (Chlamys hastata) encrusted with sponge showing eyes peering out. Vancouver Island, British Columbia, Canada
Jeff Rotman/Photolibrary/Getty Images

Scallops have about 60 eyes that line their mantle. These eyes may be a brilliant blue color, and allow the scallop to detect light, dark and motion. The eyes are visible as round dots on the image here.

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Scallops are filter feeders.

Rock scallop (Crassedoma giganteum), California
Mark Conlin/Oxford Scientific/Getty Images

Scallops eat by filtering small organisms out of the water. As water enters the scallop, mucus traps plankton in the water, and then cilia moves the food into the scallop's mouth.

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Scallops are found all over the world.

Great Mediterranean scallop
DEA PICTURE LIBRARY / De Agostini Picture Library / Getty Images

Scallops are found worldwide, and they may live from the intertidal zone to the deep sea. Most prefer sandy bottoms although some attach to rocks or other substrates.

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Scallops may grow to 9 inches in size.

Open male an female scallops
NOAA Teacher at Sea Program

Atlantic sea scallops can have very large shells up to 9 inches in length. Bay scallops are smaller, growing to about 4 inches. In Atlantic sea scallops (shown here), one can determine gender -- the female's reproductive organs are red while the male's are white.

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When you eat a scallop, you're eating the adductor muscle.

Cumbrian scallops with wild coastal cumbrian sea herbs. A dish created by chef Simon Rogan at his Cumbrian restaurant Lenclume.
Alan Spedding/Moment/Getty Images

Scallops swim by opening and closing their shells using their powerful adductor muscle. This muscle is the round, fleshy "scallop" that you eat. The adductor muscle varies in color from white to beige. The Atlantic sea scallop's adductor muscle may be 2 inches in diameter.

There are many ways to eat scallops such as eating them grilled, baked, deep fried, broiled, and pan seared. ​Click here for a list of sea scallop recipes.


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Scallops reproduce by spawning.

Pacific pink scallop, Chlamys rubida, British Columbia, Canada
Franco Banfi/WaterFrame/Getty Images

Many scallops are hermaphrodites, which means that they have both male and female sex organs. Others are only male or female.

Scallops reproduce by spawning, which is when organisms release eggs and sperm into the water. Once an egg is fertilized, the young scallop is planktonic before settling to the sea floor, attaching to an object with byssal threads. Most scallop species lose this byssus and they grow, and become free-swimming.

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Kennedy, Jennifer. "10 Facts About Scallops." ThoughtCo, Aug. 10, 2017, thoughtco.com/facts-about-scallops-2291857. Kennedy, Jennifer. (2017, August 10). 10 Facts About Scallops. Retrieved from https://www.thoughtco.com/facts-about-scallops-2291857 Kennedy, Jennifer. "10 Facts About Scallops." ThoughtCo. https://www.thoughtco.com/facts-about-scallops-2291857 (accessed February 21, 2018).