Eastern Melampus (Coffee Bean Snail / Salt Marsh Snail)
Phylum: Mollusca, Class: Gastropoda, Subclass: Heterobranchia, Order: Ellobiida, Family: Ellobiidae, Genus: Melampus, Species: Melampus bidentatus · Ellobiidae (Hollow-shelled Air-breathing Snails / Salt Marsh Snails) · Gastropod (pulmonate land/marsh snail shell); shape is obovate to top-shaped with a low conical spire and a large body whorl.
Species
Melampus bidentatus
Shell Type
Gastropod (pulmonate land/marsh snail shell); shape is obovate to top-shaped with a low conical spire and a large body whorl.
Family
Ellobiidae (Hollow-shelled Air-breathing Snails / Salt Marsh Snails)
Size
Approximately 8–12 mm in length (about 3/8 to 1/2 inch) based on its scale relative to human palm lines. This is a full-grown adult size for this small species, which typically maxes out around 10–15 mm.
Color & Pattern
Dull brownish-tan to olive-buff exterior with faint, fine axial growth lines. The apical whorls are slightly lighter gray-white, likely due to mild erosion. The interior aperture exhibits a classic thickened inner margin, revealing subtle pale/cream teeth-like folds on the columella typical of the genus.
Rarity
Very Common in its native salt marsh habitat, but often overlooked by beachcombers due to its tiny size.
Habitat
Intertidal salt marshes, mudflats, and mangrove edges, primarily living among cordgrass (Spartina alterflora) roots, high-tide drift lines, and under marsh debris.
Geographic Range
Western Atlantic Coast, ranging from Maritime Canada down along the Eastern United States, Florida, the Gulf of Mexico, and into the Caribbean.
Description
A small, sturdy, smooth-surfaced obovate shell featuring a short, blunt spire and a dominant body whorl. The aperture is narrow and elongated, with a thickened outer lip and internal columellar teeth (folds) characteristic of primitive air-breathing marsh snails.
Key Features
Obovate, coffee-bean-like shape; narrow aperture with two prominent white folds (teeth) on the lower columella; low conical spire with fine growth striations.
Collector Value
Low monetary value (typically $1–$3 for sets or educational displays), but highly valued by naturalists and micro-shell enthusiasts for local biodiversity collections.
Condition Notes
Fair to Good condition. The shell is complete and intact without major fractures. The color is somewhat faded/weathered from sun exposure on the beach drift, and the aperture contains fine beach sand grains.
Interesting Facts
Despite living in marine salt marshes, Melampus bidentatus is an air-breathing pulmonate snail with a primitive lung rather than gills. It crawls up grass stalks during high tide to avoid drowning while staying moist.
Ecological Role
Key detritivore in salt marsh ecosystems, consuming decaying plant matter and algae, and serving as a crucial food source for marsh birds, crabs, and small fish.
Similar Species
Melampus coffea (Coffee Bean Snail) - slightly larger with more distinct brown spiral bands; Detracia bullaoides - generally smoother and more glossy.
Beach Finding Tips
Look in high-tide wrack lines, salt marsh edges, and around the roots of intertidal vegetation at low tide using a magnifying glass or fine mesh sieve.