Keyhole Limpet (Alternate names: Shield Limpet, Fissurella)
Phylum: Mollusca, Class: Gastropoda, Order: Vetigastropoda, Family: Fissurellidae, Genus: Fissurella, Species: Fissurella barbadensis · Fissurellidae (Keyhole limpet family) · Gastropod (univalve), whole shell, cap-shaped or oval cone shape with an apical aperture
Species
Fissurella barbadensis (Barbados Keyhole Limpet)
Shell Type
Gastropod (univalve), whole shell, cap-shaped or oval cone shape with an apical aperture
Family
Fissurellidae (Keyhole limpet family)
Size
Approximately 1 to 1.5 inches in length. This is average for the species, which typically ranges from 0.8 to 2 inches.
Color & Pattern
Whitish to cream base color with distinct radial rows of dark brown to purplish rectangular spots or dashes around the margin. The colors appear slightly weathered and sun-bleached on the exterior, typical of beach-worn specimens.
Rarity
Common to Very Common. Easily found by dedicated beachcombers searching rocky intertidal zones and tide pools within its geographic range.
Habitat
Found in shallow intertidal and subtidal zones, tightly clinging to hard rocky substrates, wave-swept rocky shores, and coral reef frameworks where it grazes on algae.
Geographic Range
Widespread in the tropical and subtropical Western Atlantic, including the Caribbean Sea, the Gulf of Mexico, Florida, and south along the coast of South America to Brazil.
Description
This is a classic keyhole limpet featuring a conical, low-profile cap shape with a distinct apical or near-apical opening (the keyhole) at the top. The exterior exhibits prominent radial ribs crossed by fine concentric growth lines, giving the surface a beaded or textured feel. The margin is scalloped to match the radial ribs, and the interior shows a smooth porcelain-like finish with a thickened callus surrounding the keyhole opening.
Key Features
The presence of a central or subcentral perforation (the keyhole) at the apex, combined with strong radial ribs and characteristic dark brown or purplish spot markings along the outer margin.
Collector Value
Low to Moderate. While widely collected and popular among amateur shell enthusiasts for educational displays and shell crafts, they hold minimal commercial value due to their abundance.
Condition Notes
Fair to Good condition. The shell is intact with visible structural features, but shows minor beach wear, slight sun-bleaching, and dulling of the original bright coloration. Collectibility grade is Good.
Interesting Facts
The 'keyhole' at the top of the shell is not just for decoration; it serves as an exit for water after passing over the gills and for waste disposal. Living keyhole limpets press tightly against rocks to withstand heavy wave action, leaving a permanent 'scar' on the rock surface.
Ecological Role
Keyhole limpets play an essential ecological role as marine herbivores, grazing on microalgae and film algae on rocky surfaces, which helps control algal growth and maintains the balance of rocky shore ecosystems.
Similar Species
True limpets (family Lottiidae), which lack the apical perforation (keyhole) at the top of the shell.
Beach Finding Tips
Look along rocky shores, limestone formations, and tide pools during extreme low tide. Sift through shell drift accumulated in rocky crevices and tide line debris.