Buttercup Lucine (also known as the Buttercup Shell)
Phylum: Mollusca, Class: Bivalvia, Order: Lucinida, Family: Lucinidae, Genus: Anodontia, Species: Anodontia alba · Lucinidae (Lucine clams) · Bivalve (two-shelled). The specimen shown is a single valve (half-shell) with a sub-circular, inflated (globose) shape.
Species
Anodontia alba
Shell Type
Bivalve (two-shelled). The specimen shown is a single valve (half-shell) with a sub-circular, inflated (globose) shape.
Family
Lucinidae (Lucine clams)
Size
Approximately 1.5 - 2 cm (0.6 - 0.8 inches). This is a juvenile or small adult; typical adults reach 4 to 6 cm (1.5 to 2.5 inches).
Color & Pattern
Base color is a creamy white to pale yellow. It features a characteristic butter-yellow to orange-tinted wash in the center and near the umbo (beak). The pattern consists of fine, concentric growth lines. The interior (if visible) would typically be a deep egg-yolk yellow.
Rarity
Common. These shells are frequently washed up on beaches throughout their range, particularly after storms or high tides.
Habitat
Shallow marine environments, typically found in intertidal to subtidal zones. They prefer muddy or sandy substrates often associated with seagrass beds.
Geographic Range
Western Atlantic, ranging from North Carolina through the Gulf of Mexico and the Caribbean down to Brazil.
Description
A charming, orbicular bivalve characterized by its rounded, swollen appearance. The shell is thin but sturdy, with an exterior surface marked by delicate concentric growth rings. Its most striking feature is the soft, buttery yellow hue that radiates from the center, giving it its common name. The valves are nearly equilateral with a smooth, non-serrated margin.
Key Features
Sub-circular or globose shape; distinct yellow/orange interior and central exterior wash; weak or absent 'teeth' on the hinge (characteristic of the genus Anodontia); fine concentric striae without radial ribs.
Collector Value
Low monetary value ($1-$3) due to its abundance, but highly desirable for craft enthusiasts and beginner collectors due to its pleasant color and symmetrical shape.
Condition Notes
The specimen appears to be in Good to Fine condition. There is slight erosion of the growth lines near the margins and some sun-bleaching, but the characteristic yellow hue remains visible and the edge is mostly intact.
Interesting Facts
Members of the Lucinidae family have a unique symbiotic relationship with sulfur-oxidizing bacteria living in their gills. This allows them to thrive in low-oxygen, sulfide-rich environments like seagrass roots where other clams might struggle.
Ecological Role
They play a vital role in nutrient cycling within seagrass ecosystems by processing sulfides. They serve as a food source for various rays, snails, and shorebirds.
Similar Species
Lucina pensylvanica (Pennsylvania Lucine), which has a more distinct diagonal fold and deeper ribs, and Phacoides pectinatus (Thick Lucine), which is larger and more compressed.
Beach Finding Tips
Look in the 'wrack line' (debris line) after high tide on sandy Florida or Caribbean beaches. They are often found mixed in with shell hash near seagrass-heavy coastlines.