Costate Horn Snail, also known as the Ribbed Cerith or Little Horn Shell
Phylum: Mollusca, Class: Gastropoda, Order: Caenogastropoda, Family: Potamididae, Genus: Cerithidea, Species: C. costata · Potamididae (Horn Snail family) · Gastropod (univalve); whole shell with an elongated spiral/auger shape.
Species
Cerithidea costata (85% confidence based on morphology and location)
Shell Type
Gastropod (univalve); whole shell with an elongated spiral/auger shape.
Family
Potamididae (Horn Snail family)
Size
Approximately 12-15mm (approx. 0.5 inches) long. This is within the typical adult range for this species, reaching up to 20mm.
Color & Pattern
Uniformly creamy white to light tan. The color appears somewhat sun-bleached or weathered, likely lacking the darker brown periostracum seen in living specimens. No distinct banding is visible.
Rarity
Very Common. These are often found in large clusters in their preferred habitats and are frequent beach wash-up finds near mangroves.
Habitat
Commonly found in intertidal mudflats, mangrove swamps, and salt marshes. They prefer brackish or high-salinity marine environments with calm water.
Geographic Range
Western Atlantic, ranging from Florida through the Bahamas, Gulf of Mexico (Cancun/Yucatan), and the Caribbean islands to the northern coast of South America.
Description
A small, sturdy, high-spired shell featuring approximately 8 to 10 whorls. The surface is heavily sculpted with thick, vertical axial ribs (costae) that are crossed by much finer spiral threads, creating a beaded or lattice-like texture. The aperture is small and oval with a slightly thickened outer lip.
Key Features
Distinguished by its high, turreted spire, the presence of distinct vertical ribs (costae) that align somewhat from whorl to whorl, and a lack of a deep siphonal notch found in the similar Cerithiidae family.
Collector Value
Low monetary value ($0.50 - $2.00) due to high abundance. However, they are valued by collectors for diversity in a Caribbean or 'Miniature Shell' display.
Condition Notes
Good condition. The shell is intact with a sharp apex, though the aperture shows minor wear. The 'chalky' white appearance suggests it was beach-rolled and sun-bleached for some time before being found. Collectibility Grade: Fine.
Interesting Facts
These snails are incredibly resilient and can survive for long periods out of water. They crawl onto mangrove roots or marsh grass during high tide to avoid aquatic predators like crabs and fish.
Ecological Role
Important detritivore; they consume algae and decaying organic matter on the substrate, helping to recycle nutrients within mangrove and estuary ecosystems.
Similar Species
Cerithium lutosum (Dwarf Cerith) which has a more distinct siphonal canal, and Cerithium muscarum (Fly-specked Cerith) which usually has dark spots.
Beach Finding Tips
In Cancun, look in the wrack line (the debris left by high tide) on quieter beaches, especially those near the lagoon side (Nichupté) or areas with seagrass beds.
Notes
Cancun