Smooth Duck Clam (also known as the Atlantic Glass Clam or Cat's Tongue)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Mactridae, Genus: Labiosa, Species: Labiosa lineata · Mactridae (Trough shell or Duck clam family) · Bivalve (two-shelled), whole individual shown as a paired valve setup (interior and exterior views), oval to subovate shape.
Species
Labiosa lineata
Shell Type
Bivalve (two-shelled), whole individual shown as a paired valve setup (interior and exterior views), oval to subovate shape.
Family
Mactridae (Trough shell or Duck clam family)
Size
Approximately 1 to 1.5 inches in length. This is typical for adult specimens of this species, which generally range from 1 to 2 inches.
Color & Pattern
The exterior features an attractive glossy, smooth surface with a creamy or light tan base color, overlaid with a distinct network of brownish-orange to reddish-brown zig-zag or reticulated net-like patterns. The interior is smooth, pearly white to yellowish-cream with a visible pallid sinus and hinge teeth structure.
Rarity
Common, frequently found by beachcombers after storms or heavy surf along the southeastern United States and Gulf coasts.
Habitat
Found burrowing in sandy or muddy substrates in shallow marine waters, commonly inhabiting intertidal to subtidal zones, particularly in protected bays, estuaries, and along sandy ocean beaches.
Geographic Range
Western Atlantic Ocean, extending from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean Sea to South America.
Description
An elegant, thin-shelled bivalve with a smooth, polished exterior and a delicate net-like color pattern. The shell is fragile yet beautifully glossy, featuring an asymmetrical oval profile with a slightly pointed posterior end. The surface is smooth to the touch, lacking heavy ribs, and catches the light wonderfully due to its natural glossy finish.
Key Features
Distinguished by its fragile, glossy surface, distinct net-like or zig-zag brownish patterning over a cream background, asymmetrical oval shape, and the internal hinge structure typical of the Mactridae family.
Collector Value
Low to moderate commercial value, but highly prized by amateur beachcombers for its delicate beauty and vibrant net-like patterns. Typically valued at a few dollars per specimen.
Condition Notes
The specimen is in fine to gem condition, showing a bright, glossy exterior, intact margins, and a well-preserved color pattern with minimal wear or fading.
Interesting Facts
Duck clams get their common name from the broad, somewhat flattened shape of certain genera within the family. They are highly active burrowers that use a muscular, shovel-like foot to quickly bury themselves in the sand when exposed by waves.
Ecological Role
Serves as an important prey item for benthic predators such as shorebirds, crabs, and carnivorous snails. As filter feeders, they help clarify coastal waters by consuming suspended phytoplankton and organic particles.
Similar Species
Other members of the Mactridae family, such as Rangia or Spisula species, but easily distinguished by Labiosa lineata's distinct reticulated color pattern and glossy, thinner shell.
Beach Finding Tips
Look along high-tide shell lines on sandy beaches of the Gulf of Mexico and Florida after strong onshore winds or storms. Because the shells are relatively thin and fragile, searching carefully through fresh shell drift yields the best intact specimens.