Kitten's Paw (also known as the Plicate Oyster)
Kingdom: Animalia, Phylum: Mollusca, Class: Bivalvia, Order: Pectinida, Family: Plicatulidae, Genus: Plicatula, Species: P. gibbosa · Plicatulidae (Kitten's Paw family) · Bivalve (two-shelled). The specimen in the image is a single valve (either left or right). Shape: Flat, sub-triangular or fan-shaped with heavy plications.
Species
Plicatula gibbosa
Shell Type
Bivalve (two-shelled). The specimen in the image is a single valve (either left or right). Shape: Flat, sub-triangular or fan-shaped with heavy plications.
Family
Plicatulidae (Kitten's Paw family)
Size
Approximately 0.5 to 0.75 inches (12-19mm). This is typical for a juvenile or small adult; maximum size reaches about 1-1.5 inches.
Color & Pattern
Overall silvery-white to pearly-grey with high iridescence. It features faint, radiating brownish-purple or reddish spots/streaks along the ribs near the hinge (umbo). The interior is typically pearly white with a single muscle scar.
Rarity
Very Common. These shells are frequently washed up in high numbers on beaches in Florida and the Caribbean.
Habitat
Shallow marine waters, often attached to rocks, dead shells, or coral rubble by the right valve. Found in the subtidal zone down to depths of 30-50 meters.
Geographic Range
Western Atlantic, ranging from North Carolina south through the Gulf of Mexico, the Caribbean, and down to the West Indies and Brazil.
Description
A charming, small bivalve resembling a feline's foot. It is thick-walled and sturdy for its size, featuring several strong, heavy, radiating ribs (plications) that create a zigzag margin where the valves meet. The surface is rough and matte unless worn smooth by surf, and the hinge lacks teeth but has a small internal ligament pit.
Key Features
Heavy radiating ribs (usually 5 to 7 major ones), zigzag edge, asymmetric sub-triangular shape, and characteristic reddish-brown dots aligned on the ribs near the hinge.
Collector Value
Minimal monetary value (under $1 USD). It is primarily valued as a 'craft shell' for jewelry or as a charming starter shell for children and beachcombers due to its cute name and recognizable shape.
Condition Notes
Fair to Good. The shell shows significant beach-wear (erosion), which has smoothed the ribs and polished the surface to a high pearly sheen. The characteristic spots are faded but visible. Collectibility is moderate as a 'pretty' beach find, though not a 'gem' specimen.
Interesting Facts
Unlike many oysters that grow in large clusters, Kitten's Paws are usually found individually. The 'fingernail' like spots on the ribs are what give it the name 'Kitten's Paw.' The valves are 'cemented' to substrates during the animal's life.
Ecological Role
Suspension feeder that filters plankton and organic particles from the water column. They provide micro-habitats for smaller encrusting organisms on their thick shells.
Similar Species
Plicatula ramosa (slightly different ribbing) and juvenile Spondylus (Thorny Oysters), which have more complex hinges and usually retain spine bases.
Beach Finding Tips
Look in the 'shell hash' lines at low tide. They are small and often overlooked, but their pearly shine makes them stand out against darker sand and coral fragments after a storm.