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Clam Identification and Facts (From Cockles to Lucines)

Kathi was a natural sciences teacher and now writes about fossils and other earthly subjects, including clams.

Read on to learn all about a variety of clams, from cockles to lucines. You'll find helpful identifying information, interesting facts, and original photographs.

Read on to learn all about a variety of clams, from cockles to lucines. You'll find helpful identifying information, interesting facts, and original photographs.

Identify Your Clams

"Clam" can be a term that covers all bivalves such as scallops, oysters, arks and cockles, to name a few. When identifying bivalves look for color, size, shape, number of ribs and the wings or ears that project at the hinge.

Without further ado, time to get started identifying 19 clam seashells from my generous collection, which I hope will help you identify something you couldn't resist picking up from the beach! Here are the 19 clams we'll look at in this article:

  1. Atlantic Giant Cockle (Great Heart Cockle)
  2. Yellow Prickly Cockle
  3. Florida Prickly Cockle
  4. Egg Shell Cockle
  5. Bay Scallop
  6. Zigzag Scallop
  7. Lion's Paw Scallop
  8. Calico Scallop
  9. Calico Clam (Checkerboard Clam)
  10. Sunray Venus
  11. Cross Barred Venus Clam
  12. Lady-in-Waiting Venus Clam
  13. Princess Venus Clam
  14. Northern Quahog Venus Clam
  15. Southern Quahog Venus Clam
  16. Buttercup Lucine
  17. Chalky Buttercup Lucine
  18. Florida Lucine
  19. Pennsylvania Lucine

Short Video of a Clam Burrowing

Why Should We Care About Clams?

Clams have been a part of Earth's ecosystem for at least 500 million years as one of the first-ever complex organisms. They also feed the world!

Further, they leave behind their hardened calcium carbonate remains to settle at the ocean bottom. After millions of years, their shells break up, get buried under layers of sediment and then heat and pressure cement together with other sediments to form limestone, the building blocks of many a fine city building!

Finally, their shells are amazing and beautiful. Humans have found countless uses for their shells from ancient times up to the present!

Atlantic Giant Cockle or Great Heart Cockle Seashells (Dinocardium, robustum)

Atlantic Giant Cockle or Great Heart Cockle Seashells (Dinocardium, robustum)

1. Atlantic Giant Cockle (Great Heart Cockle)

The Atlantic Giant Cockle, also known as the Great Heart Cockle (Dinocardium robustum) is a very beautiful bivalve. Its shell is well-inflated, sturdy and large. It displays 32 to 36 radiating ribs and is commonly colored tan with reddish-brown patches on its outer shell and a deep pinkish interior.

In general, Cockles or Heart Shells of the U.S. Atlantic coast are close relatives to the edible cockles of Europe, although there are approximately 250 species worldwide. They are known by shell collectors for their sturdy, heart-shaped shells when both valves are clamped together, and for their attractive appearance.

Many cockles are taller than they are wide. They use a strong foot to burrow into the sand or propel themselves across the sea bottom by pushing off and even jumping several inches.

A cockle turned sideways with valves closed resembles the shape of a heart.

A cockle turned sideways with valves closed resembles the shape of a heart.

The Atlantic Giant Cockle is also known as Van Hyning's Cockle, especially if you live in the state of Florida. In 1914, the Florida Museum of Natural History's first director, Thompson Van Hyning, attempted to document Florida’s varied animal life. Today the museum houses a collection of 3 million mollusks including clams, snails, squids and octopuses.

Size, Habitat and Range

  • Size: Up to 5 inches
  • Habitat: In mud or sandy shallows, often in brackish inlets
  • Range: Virginia and south to Florida, the Gulf of Mexico, Texas and the Caribbean
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Yellow Prickly Cockle Seashells  (Trachycardium, muricatum)

Yellow Prickly Cockle Seashells (Trachycardium, muricatum)

2. Yellow Prickly Cockle

The Yellow Prickly Cockle or Yellow Cockle (Trachycardium muricatum) is a small, cherry round cockle with 20 to 40 radiating ribs. The ribs near the beak area are smooth; those farther out from the beak have small spines. The shell is yellowish-white with a delicate white to yellow-tinted interior.

Size, Habitat and Range

  • Size: Up to 2 inches
  • Habitat: Moderate shallow water
  • Range: Native from North Carolina to Florida to the West Indies, Brazil and Texas
Florida Prickly Cockle Seashells (Trachyardium, egmontianum)

Florida Prickly Cockle Seashells (Trachyardium, egmontianum)

3. Florida Prickly Cockle

The Florida Prickly Cockle (Trachyardium egmontianum) is well-inflated, medium size, has a white to tannish to light-brown exterior and a salmon, pinkish color or sometimes purple interior. The 27 to 31 radial ribs on the outer shell are more scoop-shaped than the Yellow Prickly Cockle.

Size, Habitat and Range

  • Size: Up to 3 inches
  • Habitat: Gulfs and bays, sometimes found in seagrass beds, although more common in south Texas
  • Range: North Carolina to Florida, and Texas
Egg Shell Cockle Seashells (Laevicardium,laevigatum)

Egg Shell Cockle Seashells (Laevicardium,laevigatum)

4. Egg Shell Cockle

The Egg (or Egg Shell) Cockle (Laevicardium laevigatum,) shells at first glance may be mistaken for an egg by their elongated oval shape and smooth surface. The shell is rather thin and inflated.

Its fine radial ribs are delicately etched and undetectable by touch, giving the shell's surface a smooth and polished appearance. The color is white, often tinged with brownish-orange, yellow or a hint of purple; the interior is white and sometimes slightly tinged with pink.

A fun note about this mollusk is that it has the ability to jump rather well. A shell collector reported that a live specimen in his boat even leaped to its freedom.

Size, Habitat and Range

  • Size: Up to 3 inches
  • Habitat: Shallow water sand or mud
  • Range: North Carolina to Florida and as far south as Brazil
Bay Scallop Seashells - Argopecten, irradians

Bay Scallop Seashells - Argopecten, irradians

5. Bay Scallop

Bay Scallops (Argopecten irradians) have a fan-shaped exterior shell with a color ranging from bluish gray or purplish to yellow, white, brown or reddish-brown. The lower valve is commonly white and flatter.

The interior of their valves are whitish, but often purplish near the hinge. They have inflated upper valves with 19 to 21 ribs which are squarish compared to Calico Scallops and may be banded. The wings are fairly even, but may be worn off.

When Bay Scallops are young, they attach themselves to objects such as eelgrass. This helps them avoid bottom-feeding predators, such as sea stars. As Bay Scallops grow, they drop to the sediment surface and move on to tidal flats to feed at high tide.

Bay Scallops are the most common edible shellfish.

Size, Habitat and Range

  • Size: Up to 4 inches
  • Habitat: Subtidal zones, eelgrass beds, sandy and muddy bottoms and offshore in shallow to moderately deep water, such as bays and harbors
  • Range: Maine to Florida and the Gulf of Mexico
Live Chesapeake Bay Scallop

Live Chesapeake Bay Scallop

Quick Bay Scallop Facts

  • In general, the name, "scallop," aptly describes the fluted edges of the animal's circular fan-shaped shell. Scallops otherwise known as "pectens" have rows of tiny eyes along the edge of the mantle making them unique among bivalves.
  • Scallops are jet-propelled. To explain, as their valves open, the space fills with water then the powerful muscle contracts and the valves pull shut shooting the water out and sending the scallop forward rather rapidly. This large muscle is edible. They lack the stretchy foot for digging, unique from most bivalves. Scallops are more common along the Atlantic than the Pacific coasts.
  • Early Native Americans used scallop shells in their ceremonial dances and some tribes used them as ornaments.
Zigzag Scallop Seashells (Euvola, ziczac)

Zigzag Scallop Seashells (Euvola, ziczac)

6. Zigzag Scallop

Zigzag Scallops (Euvola ziczac) have varying colored, rounded ribs that range from white to orange, yellow, gray and purple. The lower valve is somewhat cup-shaped, whereas the upper valve is fairly flat. The ear/wings are uneven.

They exhibit a zigzag pattern (enlarge above photo to see) of tiny or distinct stripes on their outer shells which gives the name. They also move in a zigzag pattern when jetting. The interior valve is whitish and purple-brown halfway to the outer edge.

Size, Habitat and Range

  • Size: Up to 4 inches
  • Habitat: Shallow waters near the shore and form beds in sandy areas
  • Range: North Carolina, throughout the Gulf of Mexico and the Caribbean and as far south as Brazil.
Lion's Paw Scallop Seashells  (Nodipecten, nodosus)

Lion's Paw Scallop Seashells (Nodipecten, nodosus)

7. Lion's Paw Scallop

Lions Paw Scallops (Nodipecten nodosus) formerly (Lyropecten nodosus). The Lion's Paw Scallop does not have the tendency to develop nodes on the ribs like other similar species. The Lion's Paw can be colored white, brown, reddish and sometimes mauve to purplish showing some spots.

They have 9 to 10 broad radiating deep ribs with additional fine lines. Look for the wide copper interior banding around the perimeter.

Size, Habitat and Range

  • Size: Up to 4 inches
  • Habitat: Fairly shallow water moderately exposed to sheltered reef systems, attached to corals and loose rubble
  • Range: Atlantic coast of North America, ranging from North Carolina to Florida, the West Indies, including Brazil and Bermuda.
Calico Scallop Seashells  (Argopecten, gibbus)

Calico Scallop Seashells (Argopecten, gibbus)

8. Calico Scallops

The pretty Calico Scallop seashells (Argopecten gibbus) are a favorite with shell collectors striving to get the greatest variety of shadings. Some collectors have a hundred Calicos, all of different color combinations.

Their mottled purple, orange, pink or even brown-hued shells commonly wash ashore, providing beachgoers with colorful treasures. They're often found with their wings/ears broken off. They have 19 to 21 roundish ribs over their fairly dome-shaped valves.

A quick note about various seashells colors: Some shells turn a variety of colors after they die. These colors depend on the shells' afterlife environment. Black shells were likely darkened by iron sulfide if buried in sulfurous muck. Pink, rust or brown are colors most shells turn after decades of exposure to air and sun.

Size, Habitat and Range

  • Size: Up to 3 inches
  • Habitat: Although closely related to bay scallops, calico scallops live in deeper, offshore waters and are found on sandy or shelly bottoms
  • Range: Native from the coast of North Carolina to Florida, the Gulf of Mexico and the West Indies
Calico Clam or Checkerboard Clam Seashells ( Macrocallista, maculata)

Calico Clam or Checkerboard Clam Seashells ( Macrocallista, maculata)

9. Calico Clam (Checkerboard Clam)

Calico Clams (Macrocallista maculata) are another popular shell among collectors, and are also known as Checkerboard Clam or Spotted Clam. It has an exterior of creamy white with a checkerboard pattern of brownish-red.

The interior is polished white with splashes of yellow or faint lavender. It has a moderately strong shell that is oval with very fine radial lines. They are edible.

Size, Habitat and Range

  • Size: Up to 2 1/2 inches
  • Habitat: Shallow sandy bottom waters
  • Range: North Carolina, Florida to the West Indies, Bermuda to Brazil
Sunray Venus Seashell (Macrocallista, nimbosa)

Sunray Venus Seashell (Macrocallista, nimbosa)

10. Sunray Venus

Sunray Venus (Macrocallista nimbosa) has also been called Giant Callista. Its outer valve is violet gray to tan-ish with darker streaks radiating out from the hinge. The interior is dull white with a tinge of red over the central area.

Fresher specimens are more pinkish. It has an elongated oval-shaped shell with a glossy, smooth surface. They are edible.

Native Americans used the Sunray Venus shell as eating utensils.

This Venus Shell is named for the Goddess Venus and is noted for its graceful lines and beauty of color and sculpture.

Size, Habitat and Range

  • Size: Average is 3 inches, but can grow up to 4 inches
  • Habitat: Sandy ocean bottoms in shallow water
  • Range: Native to Florida's West Coast, St. Petersburg to Marco, the beginning of the Everglades Islands and found as far north as North Carolina and west to Texas

11. Cross Barred Venus Clam

The Cross Barred Venus (Chione cancellata) is a small, roundish triangular clam marked by distinct radiating and crossover lines, giving it a miniature lattice-work appearance.

The slightly inflated shell is whitish often with brown markings. The inner surface of the shell also displays a pretty purple color. Gather enough of the living clams and you can make a delicious chowder.

Size, Habitat and Rnge

  • Size: Up to 2 1/2 inches
  • Habitat: More abundant in vegetative areas of bays
  • Range: North Carolina to Florida, south to the West Indies and east to parts of the Gulf of Mexico
Lady-in-Waiting Venus Clam Seashell  (Puberella, intapurpurea)

Lady-in-Waiting Venus Clam Seashell (Puberella, intapurpurea)

12. Lady-In-Waiting Venus Clam

Lady-in-Waiting Venus Clam (Puberella intapurpurea, formerly, Chione intapurpurea), has a triangular, concave sturdy shell with distinct concentric ridges and vertical beads or ridges giving it a cross-hatched look.

The lower margin or edge of the shell is serrated similar to teeth, notably visible from the interior. They have a prominent inward beak and are colored a pale yellow to off-white, sometimes with brown patches or freckles.

I wish I knew how this pretty little Venus clam was named. In human culture, a "lady-in-waiting" is a female companion or personal assistant to a royal or noblewoman of high rank.

Size, Habitat and Range

  • Size: Up to 1 1/2 inches
  • Habitat: Sandy bottom in fairly shallow water
  • Range: North Carolina to Florida, as far south as Brazil and east to Texas' Gulf Coast
Princess Venus Clam Seashells (Periglypta, listeri)

Princess Venus Clam Seashells (Periglypta, listeri)

13. Princess Venus Clam

The Princess Venus Clam (Periglypta listeri) is heart-shaped with numerous fine concentric rings and fine radial ribs over its exterior. It has a fairly inflated sturdy shell with a distinct serrated edge reminiscent of fine teeth, observed from the interior.

I love this little seashell for its deep brown exterior color's contrast with its striking white interior, often accompanied by purplish stains.

Size, Habitat and Range

  • Size: Up to 2 inches
  • Habitat: Buries in gravel, sand and mud in mid-intertidal zones
  • Range: Florida to the Caribbean
Northern Quahog Seashells (Mercenaria, mercenaria)

Northern Quahog Seashells (Mercenaria, mercenaria)

14. Northern Quahog Venus Clam

The Northern Quahog (Mercenaria mercenaria)—pronounced "co-hog"—is a large, thick, hard-shelled clam, also known as a type of Venus Clam. It's often round to oval in shape and may be very plain or decorated with ridges of thin concentric, colorful lines or rays.

The Northern Quahog is more colorful than its southern cousin, with a beautiful interior decorated with deep purple swirls.

The Northern Quahog was prized by Native Americans and was an important part of their diets. They used the shells to painstakingly make the colorful beads for "wampum" belts which served to bind treaties. The Native Americans also called the smaller ones "Littleneck" or "Cherrystone" clams.

The name "quahog" comes from the Native American name "poquauhock," meaning horse fish. The Latin name Mercenaria mercenaria is derived from a word that means wages and was given to the quahog due to the Native American use of wampum as money and jewelry.

Size, Habitat and Range

  • Size: Up to 6 inches
  • Habitat: Offshore burrowing in sand or mud in shallow water
  • Range: Nova Scotia, Canada to Florida and east to Texas
Southern Quahog Seashells (Mercenaria, campechiensis)

Southern Quahog Seashells (Mercenaria, campechiensis)

15. Southern Quahog Venus Clam

The Southern Quahog (Mercenaria campechiensis)—pronounced "co-hog"—is a type of Venus Clam known as hard-shell clams that have large, thick, sturdy, inflated shells with concentric ridges over their entire surface.

The Southern Quahog beaks grow inward toward the anterior. Their outer shells are grayish to brown to white. Their interior shell is chalky white, and lacks the purple characteristic of its cousin, the Northern Quahog, but can have hints of purple. They possess two muscle scars on the interior surface of each valve.

Quahogs are extremely efficient filter feeders, and large quahogs can filter about a gallon of water per hour. Quahogs are prized as food for humans and constitute one of Rhode Island's most important fisheries.

Size, Habitat and Range

  • Size: Up to 7 inches and slightly larger than their cousins, the Northern Quahog
  • Habitat: Burrows offshore in intertidal zones under sand or mud to a water depth of 120 feet, and may also be found in salt marshes
  • Range: Cape Cod, Canada to Florida, as far south as Cuba and west to the Gulf of Mexico and the Mexican Coastline
Buttercup Lucine Seashells (Anodontia, alba)

Buttercup Lucine Seashells (Anodontia, alba)

16. Buttercup Lucine

The Buttercup Lucine or Lucina (Anodontia alba) is a circular, bowl-shaped, small bivalve with a fairly sturdy white outer shell and creamy to butter yellow interior. The exterior has numerous fine concentric lines and a somewhat wide hinge plate.

Lucines are common in warm waters on both the Atlantic and Pacific Coasts of North America. They are not edible.

Did you know the Lucines are named for Lucina, an aspect of the Roman Goddess, Juno, who represented light and childbirth?

Size, Habitat and Range

  • Size: Up to 2 inches
  • Habitat: Deep to shallow water
  • Range: North Carolina to Florida and the West Indies, as well as the U.S. Pacific Coast
Chalky Buttercup Lucine Seashells (Anodonitia, philipiana)

Chalky Buttercup Lucine Seashells (Anodonitia, philipiana)

17. Chalky Buttercup Lucine

The Chalky Buttercup Lucine (Anodonitia philipiana) is slightly thicker and also larger than the Buttercup Lucine (Anodontia alba). The valve color is white with only a pale yellow interior and possesses numerous concentric lines with a dominant furrow.

Size, Habitat and Range

  • Size: Up to 2 1/2 inches
  • Habitat: Deep water, but can reach the beach when tidal flow washes it up
  • Range: North Carolina to Florida and the Gulf states, as well as south to the West Indies
Florida Lucine Seashells - Pseudomiltha floridana

Florida Lucine Seashells - Pseudomiltha floridana

18. Florida Lucine

The Florida Lucine or Lucina (Pseudomiltha floridana) shows weak growth lines but a sturdy shell. Both its exterior and interior valve colors are white. The shell is fairly inflated and very round with a beak that turns forward and is small, but prominent.

They have been called the Face Shell because they are used for the faces of shell dolls. They are not edible.

Size, Habitat and Range

  • Size: Up to 1 1/2 inches
  • Habitat: Moderate shallow water
  • Range: Florida to Texas and the U.S. Pacific Coast
Pennsylvania Lucine Seashell (Linga, pennsylvanica)

Pennsylvania Lucine Seashell (Linga, pennsylvanica)

19. Pennsylvania Lucine

The Pennsylvania Lucine or Lucina (Linga pennsylvanica) is white with distinct concentric ridges and a distinct diagonal furrow about the posterior region. The shell is sturdy, heart-shaped and inflated with a beak inclined forward.

Beach-worn specimens are smooth and shiny. They are not edible.

Size, Habitat and Range

  • Size: Up to 2 inches
  • Habitat: Shallow water
  • Range: North Carolina to Florida and the West Indies, as well as the U.S. Pacific Coast

I hope you enjoyed my photos and descriptions of those curious clams!

Sources

© 2019 Kathi Mirto

Comments

Flamingo Emporium on May 23, 2020:

The top mystery shell appears to be nothing more than the center twist of a conch that is well worn by the surf

Kathi Mirto (author) from Fennville on January 24, 2019:

Glad you liked it, thank you Linda!

Linda Crampton from British Columbia, Canada on January 20, 2019:

Thank you for sharing so many interesting facts about clams, Kathi. The photos are beautiful.

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