Keyhole Limpet
Phylum: Mollusca, Class: Gastropoda, Order: Lepetellida, Family: Fissurellidae, Genus: Fissurella, Species: Fissurella barbadensis · Fissurellidae (Keyhole Limpet family) · Gastropod (univalve), whole shell, cap-shaped (patelliform) with a distinct apical aperture
Species
Fissurella barbadensis (Barbados Keyhole Limpet)
Shell Type
Gastropod (univalve), whole shell, cap-shaped (patelliform) with a distinct apical aperture
Family
Fissurellidae (Keyhole Limpet family)
Size
Approximately 0.75 inches (1.9 cm) in length, which is average for this species. Adults typically range from 0.5 to 1.5 inches.
Color & Pattern
Exterior features radial ribs crossed by concentric growth lines, creating a beaded texture. Alternating bands of white, cream, and reddish-brown or grayish-brown radiate outward from the apex. The interior is glossy white with a greenish-blue central area and a distinctive brown-bordered keyhole foramen.
Rarity
Common; frequently found by beachcombers and tidepool explorers in its native tropical and subtropical range.
Habitat
Found primarily in the intertidal zone attached firmly to hard substrates such as rocks, coral rubble, and tide pools where wave action is moderate to high. Marine environment.
Geographic Range
Western Atlantic Ocean, including the Caribbean Sea, the Gulf of Mexico, southern Florida, Bermuda, and down to Brazil.
Description
A charming and uniquely shaped cap-shaped marine snail shell featuring a distinctive oval keyhole opening near the apex. The exterior exhibits prominent radial ribs and a scalloped margin. The interior showcases a smooth, porcelain-like finish with delicate pastel green and white tones surrounding the central perforation used by the living animal for water excretion and respiration.
Key Features
The presence of a central or subcentral apical opening (foramen) combined with strong radial ribbing and scalloped margins clearly separates keyhole limpets from true limpets (Patellidae), which lack any shell perforation.
Collector Value
Low to moderate commercial value, but highly prized by amateur beachcombers and micromollusk collectors for their fascinating morphology and clean aesthetic. Typically sells for under a dollar to a few dollars depending on size.
Condition Notes
Gem condition. The shell is intact, clean, retains vibrant natural coloration, clear radial patterns, and has an undamaged central keyhole margin.
Interesting Facts
The 'keyhole' opening is not just for show; it serves as an exit for water after it passes over the gills, as well as for waste elimination. Unlike traditional snails, keyhole limpets possess two gills instead of one.
Ecological Role
Keyhole limpets are important marine herbivores, grazing on microalgae and encrusting films on rocks, which helps maintain the balance of rocky intertidal ecosystems. They are preyed upon by predatory gastropods, crabs, and shorebirds.
Similar Species
Fissurella fascicularis (Intertwined Keyhole Limpet) and Fissurella angusta, which can be distinguished by differences in rib density, profile height, and the exact shape and position of the keyhole aperture.
Beach Finding Tips
Look along rocky shores, limestone formations, and tide pools during extreme low tides in the Caribbean or southern Florida. Check under loose rocks or inside crevices where they cling tightly.