Buttercup Lucine, Pennsylvania Lucine
Kingdom: Animalia, Phylum: Mollusca, Class: Bivalvia, Subclass: Heterodonta, Order: Lucinida, Family: Lucinidae, Genus: Lucina, Species: Lucina pensylvanica · Lucinidae (Lucine family) · Bivalve (single valve); shape is sub-circular to heart-shaped (cordate) with a distinct posterior fold.
Species
Lucina pensylvanica (95% confidence)
Shell Type
Bivalve (single valve); shape is sub-circular to heart-shaped (cordate) with a distinct posterior fold.
Family
Lucinidae (Lucine family)
Size
Approximately 1.5 to 2 inches (38-50mm) in diameter. This is a mature adult size for the species, which typically peaks around 2 inches.
Color & Pattern
Uniformly chalky white to creamy ivory. The exterior shows faint concentric growth lines and a pitted texture where the periostracum has eroded. The interior (not fully visible) is typically white with a polished, slightly yellow or 'buttery' tint in the center of the valve.
Rarity
Common; frequently found on beaches across the Caribbean and Gulf regions, though large, perfectly intact valves with the periostracum are less common.
Habitat
Marine; found in shallow subtidal waters ranging from 0 to 100 feet deep. They prefer sandy substrates, often near seagrass beds or coral reef environments.
Geographic Range
Western Atlantic: found from North Carolina through Florida, the Bahamas, the Gulf of Mexico (including Cancun/Yucatan), and throughout the Caribbean to the West Indies.
Description
A robust, thick-walled bivalve characterized by its rounded, globe-like inflation. It features a very prominent, deep groove or 'fold' that runs from the beak (umbo) to the posterior margin, giving it a slightly asymmetrical, tucked-in appearance. The surface is textured with concentric rings and fine pitting.
Key Features
The most diagnostic feature is the deep posterior groove/fold and the sharp, curved beak. It is much thicker and more circular than most other clams found in the Caribbean.
Collector Value
Low; due to its abundance and the damage visible on this specimen, it has minimal monetary value (under $1). It is a classic 'memory' shell for beachcombers rather than a high-end investment piece.
Condition Notes
Fair condition. The shell is beach-worn and sun-bleached, having lost its yellowish-thin periostracum. There is a significant puncture/breakage near the ventral margin (possibly from a predator or wave impact), which lowers its collector grade to 'Fair' or 'Reference.'
Interesting Facts
Lucine clams have a fascinating symbiotic relationship with chemosynthetic bacteria living in their gills. These bacteria oxidize hydrogen sulfide from the sand to provide nutrients to the clam, allowing the species to thrive in sulfur-rich, low-oxygen sediments.
Ecological Role
Primary consumer/filter feeder and host to symbiotic bacteria. They help detoxify sediments by removing hydrogen sulfide, making the environment more hospitable for other marine life like seagrass.
Similar Species
Codakia orbicularis (Tiger Lucine), which is larger, flatter, and has radiating ribs rather than a deep posterior fold; and Phacoides pectinatus (Thick Lucine), which lacks the signature deep posterior groove.
Beach Finding Tips
Look along the high-tide line after a storm. In Cancun, these are often found mixed in with coral rubble and smaller white clam fragments. Their weight often causes them to settle deeper in the shell pile than thinner shells.
Notes
Cancun