Keyhole Limpet
Phylum: Mollusca, Class: Gastropoda, Order: Lepetellida, Family: Fissurellidae, Genus: Fissurella, Species: Fissurella barbadensis · Fissurellidae (Keyhole limpet family) · Gastropod (univalve), cap-shaped shell with an apical perforation
Species
Fissurella barbadensis
Shell Type
Gastropod (univalve), cap-shaped shell with an apical perforation
Family
Fissurellidae (Keyhole limpet family)
Size
Approximately 1 to 1.5 inches in diameter, which is average for this species. Adults typically range from 0.75 to 2 inches.
Color & Pattern
Features a grayish-white or cream base color adorned with distinct radial brownish-black stripes or alternating dark and light ribs. The interior is glossy white with a smooth margin.
Rarity
Common
Habitat
Found in intertidal and shallow subtidal zones, typically clinging firmly to hard rocky substrates, reefs, and tide pools where wave action is moderate to high.
Geographic Range
Western Atlantic Ocean, including the Caribbean Sea, the Gulf of Mexico, Florida, and south along the coast of South America to Brazil.
Description
A charming and compact cap-shaped shell characterized by strong, radiating ribs and a distinctive oval opening (the keyhole) near the apex. The margin is finely crenulated, and the exterior sculpture shows a rugged, textured grid pattern formed by intersecting growth lines and ribs.
Key Features
The presence of a prominent apical or near-apical perforation (the 'keyhole') used for expelling waste and water, combined with strong radial ribbing and alternating dark-and-light color patterns.
Collector Value
Modest value. While widely collected and common in shell shops, nice specimens with clear radiating patterns are always appreciated by beginner and intermediate shell collectors.
Condition Notes
The shell appears to be in good, intact condition with natural coloration well-preserved, minimal wear on the ribs, and a clean interior, grading as Fine.
Interesting Facts
The keyhole is not just for decoration; it functions as an exhalant pore. Water flows in under the rim of the shell over the gills and exits through the keyhole carrying waste away from the animal.
Ecological Role
Keyhole limpets are important marine herbivores that graze on microscopic algae coating rocks, helping to keep algal growth in check and maintaining healthy micro-habitats in intertidal zones.
Similar Species
Other Fissurella species such as the Lobe Keyhole Limpet (Fissurella listeri), which can be distinguished by differences in the shape and position of the keyhole and specific ribbing patterns.
Beach Finding Tips
Look along rocky shores, limestone formations, and tide pools at low tide. Search among drift lines or examine rocks where attached limpets may have washed ashore post-mortem.