Angel Wing (also known as the Atlantic Angel Wing)
Phylum: Mollusca, Class: Bivalva, Subclass: Heterodonta, Order: Myida, Family: Pholadidae, Genus: Cyrtopleura, Species: Cyrtopleura costata · Pholadidae (Angel Wing or Piddock family) · Bivalve (two-shelled mollusk); single valve presented. Elongated, wing-like shape.
Species
Cyrtopleura costata
Shell Type
Bivalve (two-shelled mollusk); single valve presented. Elongated, wing-like shape.
Family
Pholadidae (Angel Wing or Piddock family)
Size
Approximately 4 to 5 inches in length. This is a very good size for this species, as typical adult shells range between 4 and 7 inches.
Color & Pattern
Off-white to chalky ivory tone throughout, consistent with natural sun-bleached exposure or sand burial. Fine gray/buff silt accumulation visible in the lattice crevices. Missing the original thin, pale yellow-brown periostracum shell layer.
Rarity
Uncommon as a complete or large beach find. While living populations are abundant in muddy substrates, intact valves—especially large ones like this—rarely survive ocean surf intact due to their extremely fragile, thin nature.
Habitat
Burrows deeply (up to 2 feet down) into intertidal and shallow subtidal muddy sand, clay, or soft substrate. Marine environments with low-to-moderate wave energy.
Geographic Range
Western Atlantic from Cape Cod, Massachusetts, south to Florida, the Gulf of Mexico, the Caribbean, and down to Brazil. Commonly found along the Atlantic coast of North Carolina including Oak Island.
Description
A stunning, elongated single valve of the Atlantic Angel Wing featuring its characteristic delicate, sculpture-rich surface. The exterior exhibits prominent radial ribs intersecting with concentric growth lines, creating a beaded or lattice-like reticulated pattern that resembles delicate feathered wings. The anterior end is flared with sharp, scaly ribbing used for burrowing.
Key Features
Distinctive elongated, wing-like shape; deeply sculptured radial ribs with cross-hatching beaded nodes; lack of a true hinge ligament (possesses an umbonal reflection and accessory plates in live specimens); extremely thin and brittle shell structure.
Collector Value
Desirable beach find due to its fragility and striking appearance. Value ranges from $5 to $20 depending on size, intactness, and whether it is a matched pair. Matched pairs with intact accessory plates are highly prized by collectors.
Condition Notes
Good to Very Good beach-found condition. Excellent preservation of the delicate lattice sculpturing and outer margin teeth. Shows typical sun-bleached calcification and minor erosion at the posterior tip, but remarkably intact for a thin-shelled piddock species found on a public beach. Collectibility grade: Fine.
Interesting Facts
The living animal uses its rasp-like shell and muscular foot to slowly bore deep burrows into clay or mud that it never leaves. The animal is so large compared to its shell that it cannot completely retract inside! The living tissue is also bioluminescent, glowing with a soft blue-green light when disturbed.
Ecological Role
Deep-burrowing suspension feeder that filters plankton and detritus from the water column. Their deep burrows help oxygenate muddy sediments, and empty burrows provide habitat for small invertebrates. Not threatened or endangered, but sensitive to severe coastal habitat destruction.
Similar Species
False Angel Wing (Petricolaria pholadiformis), which is much smaller (around 2 inches) and lacks the strong radial beaded sculpture; Campeche Angel Wing (Pholas campechiensis), which has distinct septa/partitions inside.
Beach Finding Tips
Look near muddy sound-side beaches or along oceanfront tide lines right after low tide or following winter storms. Because they are fragile, check around calm tidal flats, marshes, or sheltered sandy stretches like those found near the west end or tidal inlets of Oak Island, NC.
Notes
Oak Island NC