Eastern Mud Snail (also known as Eastern Mud Nassa or Mud Dog Whelk)
Phylum: Mollusca, Class: Gastropoda, Subclass: Caenogastropoda, Order: Neogastropoda, Family: Nassariidae, Genus: Tritia, Species: Tritia obsoleta · Nassariidae (Nassa mud snails / Basket snails) · Gastropod (univalve snail), high-spired conical shell, complete specimen with visible aperture
Species
Tritia obsoleta (formerly Ilyanassa obsoleta)
Shell Type
Gastropod (univalve snail), high-spired conical shell, complete specimen with visible aperture
Family
Nassariidae (Nassa mud snails / Basket snails)
Size
Approximately 8-10 mm (about 0.3-0.4 inches) long, estimated relative to human fingertips. Typical adult size ranges between 12-25 mm (0.5-1.0 inch), making this a juvenile or small adult specimen.
Color & Pattern
Dark grayish-brown to purplish-black exterior with alternating light grayish-tan spiral bands and beaded axial ribs. The aperture (opening) is dark brown with a smooth whitish to pale purple columella.
Rarity
Very Common (extremely abundant in native mudflat habitats).
Habitat
Intertidal and shallow subtidal zones, predominantly soft-bottomed estuaries, mudflats, salt marshes, and protected bays. Marine to brackish water environment.
Geographic Range
Native to the Western Atlantic coast of North America from Nova Scotia to northern Florida. Introduced and established along parts of the US Pacific Coast (California to Washington).
Description
A small, sharply conical gastropod shell with high spires. The sculpture features prominent spiral cords intersected by axial ribs, creating a distinct beaded or reticulated texture. The outer lip is thin and smooth internally, while the oval aperture has a short, distinct anterior siphonal notch typical of the Nassariidae family.
Key Features
Conical high-spired shape, reticulated/beaded exterior texture formed by intersecting grid-like ribs, dark brownish-gray color, small oval aperture with a pronounced anterior siphonal canal notch.
Collector Value
Low monetary value due to extreme abundance, but valued by micro-shell collectors and enthusiasts for its delicate beaded sculpture and ecological significance. Estimated value: < $1 USD.
Condition Notes
Good condition. Features a fully intact spire, clear surface sculpture, intact outer lip, and minimal shell erosion or beach wear.
Interesting Facts
Tritia obsoleta is a opportunistic scavenger that forms dense aggregations on intertidal mudflats, sometimes reaching densities of thousands per square meter. Living snails locate dead animal matter using highly sensitive chemoreceptors in their extended siphon.
Ecological Role
Key benthic scavenger and detritivore on mudflats, helping recycle nutrients by feeding on microalgae, detritus, and dead organisms. Serves as a vital food source for shorebirds, crabs, and fish.
Similar Species
Nassarius vibex (Mottled Dog Whelk, which is stockier with stronger parietal callus) and Bittium alternatum (Alternate Bittium, which is much more slender and needle-like).
Beach Finding Tips
Look along low-tide mudflats, salt marsh edges, and soft estuarine sands. Often found by searching the wrack line or sifted sand near quiet bays and inlets.