Eastern Mud Snail / Atlantic Mud Nassa (alternate: Eastern Mud Nassa)
Phylum: Mollusca - Class: Gastropoda - Subclass: Caenogastropoda - Order: Neogastropoda - Superfamily: Buccinoidea - Family: Nassariidae - Genus: Tritia - Species: T. obsoleta · Nassariidae (Nassa mud snails / Dog whelks) · Gastropod (univalve snail). Whole shell with a classic high-conical/ovate spiral shape.
Species
Tritia obsoleta (formerly Ilyanassa obsoleta)
Shell Type
Gastropod (univalve snail). Whole shell with a classic high-conical/ovate spiral shape.
Family
Nassariidae (Nassa mud snails / Dog whelks)
Size
Approximately 8-12 mm in length (under 0.5 inches) based on comparison with human fingertips. Full-grown adults typically reach 15-25 mm, making this a small or juvenile specimen.
Color & Pattern
Pale grayish-white to light tan base background color, decorated with thin brownish spiral dashed lines along the sculpture. The exterior shows fine spiral cord grooves. The interior of the aperture is smooth and pale off-white.
Rarity
Very Common within its native range along mudflats and estuarine shores.
Habitat
Intertidal and shallow subtidal estuarine environments, specifically mudflats, salt marshes, and protected bays with soft muddy or sandy-mud sediments. Marine to brackish water.
Geographic Range
Native to the Western Atlantic coast from Nova Scotia to Florida. Introduced to the Pacific coast of North America (from Washington to California) and parts of Europe.
Description
A small, sturdy, high-spired gastropod with fine spiral sculpting along its whorls. The apex is pointed, leading down to a gently inflated body whorl. The aperture is oval with a short, notched siphonal canal at the base, characteristic of the mud nassa family. The shell exhibits subtle brownish dashed spiral bands on an off-white background.
Key Features
Conical high spire, oval aperture with a short, distinct siphonal notch, fine spiral cord grooves around each whorl, and delicate brown dashed spiral patterning.
Collector Value
Low monetary value due to extreme abundance ($0.50 - $2.00), but highly valued by micro-shell collectors and educators for demonstrating estuarine biodiversity.
Condition Notes
Good to Fine condition. The shell structure, aperture, and outer lip are fully intact. The colors appear slightly beach-worn or sun-bleached compared to live-collected dark brown specimens, but the characteristic dashed spiral bands remain clearly visible.
Interesting Facts
Living mud snails aggregate in massive densities on mudflats, reaching thousands of individuals per square meter. They possess an extremely keen chemical sense (olfaction) that allows them to detect decaying organic matter or dead animals from considerable distances in calm water.
Ecological Role
Extremely important estuarine scavenger and deposit feeder that recycles organic detritus and microalgae. They serve as a primary food source for shorebirds, crabs, and fish, though they can outcompete native species where introduced.
Similar Species
Nassarius vibex (Eastern Mud Snail/Vibex Nassa), which features stronger axial ribs and a heavy callus on the aperture, and Tritia trivittata (Threetiered Mud Snail), which has a more deeply beaded sculpture.
Beach Finding Tips
Search along calm, sheltered intertidal mudflats, salt marsh edges, and bay beaches during low tide. They are often found washed up along the high-tide wrack line or floating debris.