Rayed Trough Shell, also known as Rayed Clam or Mactra
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Mactridae, Genus: Mactra, Species: Mactra corallina · Mactridae (Trough shell family) · Bivalve (two-shelled), whole shell, fan/triangle-shaped
Species
Mactra corallina
Shell Type
Bivalve (two-shelled), whole shell, fan/triangle-shaped
Family
Mactridae (Trough shell family)
Size
Approximately 1.5 to 2 inches in width, which is typical for an adult specimen of this species. Adults generally range from 1 to 3 inches.
Color & Pattern
The exterior features a glossy, creamy or light tan base color adorned with distinct, radiating white and darker brown stripes running from the umbo (beak) to the margin. It also displays subtle concentric growth lines and a darker patch near the posterior slope. The colors are natural and well-preserved with a shiny, polished finish.
Rarity
Common to Uncommon depending on local beach conditions, but nice whole specimens with intact patterns are appreciated finds for beachcombers.
Habitat
Inhabits shallow subtidal and intertidal zones, typically burrowing in clean fine sand or muddy-sand substrates along sandy beaches and coastal marine environments.
Geographic Range
Eastern Atlantic Ocean, including the Mediterranean Sea and European coasts, extending down to West Africa. Well-documented along the coasts of Portugal, such as the Algarve region.
Description
An attractive, robust, yet sleek bivalve shell with a smooth, glossy surface. It features a triangular to sub-oval outline with a prominent, slightly inflated umbo centrally located. The striking rayed pattern of contrasting white and brown lines gives it a decorative appearance, while the interior is smooth and porcelain-white.
Key Features
Distinctive triangular-oval shape, prominent central umbo, smooth polished exterior texture, and characteristic radial bands of white and brown over a tan background.
Collector Value
Low to moderate commercial value, but highly desirable for regional shell collections and decorative displays due to its pleasing geometric ray patterns and glossy finish.
Condition Notes
Fine to Gem condition. The shell is intact with no major fractures, featuring well-preserved original coloration, minimal wear on the margins, and a glossy natural finish.
Interesting Facts
Mactra species are active burrowers using a strong, muscular foot to rapidly dig themselves back into the sand if exposed by waves. They play an important role in benthic food webs.
Ecological Role
Functions as a filter feeder, consuming phytoplankton and organic particles from the water column. Serves as a vital food source for marine predators such as crabs, rays, and carnivorous sea snails.
Similar Species
Spisula solida (Thick trough shell), which is generally thicker, heavier, and less distinctly rayed compared to Mactra corallina.
Beach Finding Tips
Look along high-energy sandy beaches after stormy weather or strong incoming tides. Sifting through fresh driftlines or checking shallow sandbars at low tide yields the best results.
Notes
Lagos portugal