Bruised Nassa,Giant Bittersweet and Lettered Olive

Bruised nassa- Nassarius vibex (Say) is a small shell (about 1/2") with a rough surface. It has a coarsely beaded surface with equal spiral and axial ribs, resulting in about 12 ridges. It has a smooth inner lip with prominent parietal shield. It has a thick and toothed outer lip. It has a grayish brown exterior with a prominent cream-colored shield. It found in shallow-water sand flats on sound and ocean beaches. A scavenger, it also has been observed feeding on eggs of marine worms. (information from "Seashells of North Carolina by Porter and Houser North Carolina Sea Grant College Program")

Giant Bittersweet, Glycymeris americana (DeFrance)

Grows to 4 inches, is round and a somewhat flat shell. Indistinct broad radial ribs sculptured with radiating scratches. It has a central beak and a long curved hinge with 19-24 teeth. It's color is a grayish tan exterior and mottled with yellowish borwn. It lives offshore in depths of 75 feet near and south of the Capefear river. (Information from "Seashells of North Carolina by Porter and Houser - North Carolina Sea Grant College Program")

Lettered olive, Oliva sayana (Ravenel) A smooth, shiny, cylindrical shell with a short spire. Narrow aperture extending almost length of shell, continuing around the bottom and ending in a notch on the other side. No operculum. It's cream or grayish exterior with reddish brown zigzag markings and lives in near-shore waters on shallow sand flats near inlets. It's commonly washed onto ocean beaches. A carnivore, it captures bivalves and small crustaceans with its foot and takes them below the sand surface to digest. Its presence is sometimes detected at very low tides by the trails it leaves when it crawls below the surface on semi-exposed sand flats.

Marsh Periwinkle and Florida Melampus

This is a Marsh Periwinkle, Littorina irrorata.
5/8-1 1/2" (1.6-3.8cm) high. These were found on the high tide line on Ocean Isle Beach, NC. Broadly ovate, think, sharply pointed except when eroded; Whorls smooth, slightly convex. Columellar area and inside of outer lip whitish, the latter with a dark margin and dark brown deep within. Habitat: on rocks intertidally. In Europe, this very common and abundant shell is still gathered and eaten by many people. Information from "The Audubon Society Field Guide to North American Seashells pages 401-2.

The Florida Melampus, Detracia floridana is found at the high tide line. (5/8 ") Small, cone-shaped shell with a short, blunt spire. Long, narrow aperture with front end expanded. Color: Light to dark brown, occasionally with three to four darker-colored spiral bands. Also called a salt-marsh snail, this family has a primitive lung in place of gills and breathes air. The snail eats decaying plant matter but is believed to get its nutrients from the bacteria that live on decaying matter. Information found in"Seashells of North Carolina - NC Sea Grant College Program Porter and Houser".

I received an email from Terri Kirby Hathaway from the NC Sea Grant website and she writes...
Your shells are the eastern mudsnail (/Ilyanassa obsoleta/), very commonin NC estuaries. This animal is also called eastern mud nassa, mud dogwhelk, and the common mudsnail. We find lots of them up here on DareCounty beaches.



"Ilyanassa obsoleta (Say, 1822)

EASTERN MUDSNAIL. COMMON MUD SNAIL, EASTERN MUD WHELK, MUD DOG WHELK, BLACK DOG WHELK, WORN-OUT DOG WHELK, EASTERN MUD NASSA, MUD BASKET SNAIL, OBSOLETE BASKET SNAIL

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Prosobranchia
Order: Neogastropoda
Family: Nassariidae

Ilyanassa obsoleta has a plain, dark black or brown shell, 1.5-3 cm high, with 5-6 whorls (a whorl is one complete turn of the spiral shell) and a blunt, conical spire. The shell's surface is decorated with a network of weak, beaded lines. The aperture (the opening through which the snail emerges) is roughly oval and about half the height of the shell, with a notch at the bottom. The outer rim of the aperture is thin and sharp, and the inner side of the aperture has a spiral fold near its base. The inside surface of the shell is a deep, purplish black. The shell is often covered with mud and algae (and sometimes with the Atlantic bryozoan Alcyonidium polyoum), and in most older snails the tip of the shell is eroded.

Ilyanassa obsoleta is the most abundant intertidal snail on San Francisco Bay mudflats and in the lower reaches of marsh channels, where it is often found in large herds. As this snail crawls over the mud surface it leaves a grooved trail behind, and when the tide goes out it usually burrows under the surface to avoid drying out. It has been collected in the bay in salinities of 10-32 ppt and water temperatures of 13-22° C. It feeds on diatoms and algal detritus that it gleans from the surface layers of the mud, captures and consumes minute worms (in the family Spionidae) that live in the mud, and scavenges on dead fish, crabs and other animal remains. It is fed on in turn by ducks and the larger shorebirds.

Ilyanassa obsoleta deposits its eggs in small, bristly, faceted capsules that are attached to hard surfaces. Each capsule is about 3 mm high and contains several eggs. The capsules are often laid in rows on eelgrass blades, or in rows or clusters on shells, stones or debris on the mudflats. The young snails emerge as free-swimming larvae. The larvae drift in the plankton for 20-30 days, feeding on phytoplankton, before settling to the bottom and metamorphosing into tiny snails. Ilyanassa obsoleta can live for up to 5 years.

The San Francisco Bay mudflats where Ilyanassa obsoleta is now found were once occupied by the native hornsnail Cerithidea californica. Race (1982) describes how each spring the two populations of these snails collide in the lower marsh channels. By mid-summer Ilyanassa obsoleta has restricted the native hornsail to the upper channels and shallow pools in the upper marsh through a combination of egg predation and direct competitive interference. The high marsh pools (also called salt pannes) are too salty for Ilyanassa obsoleta, and thus provide a habitat refuge for the native snail."
from the website: http://www.exoticsguide.org/species_pages/i_obsoleta.html

They also mention that these are not a native species on the west coast and probably came in with a shipment of atlantic clams in the early part of the 20th century.

Shell identification...cont.

They seem to run from16-20mm.

Thanks for your help!

Identification problem

I quit! I've looked at just about all the places google says to go, to find the name of these shells. I think they're periwinkles and I've looked at littoraria, spurwinkia, laemodonta and myosotella and when there were pictures, none of them looked like these banded shells. I sure can use the help. They were found on our crab pot in the canals of Ocean Isle Beach, NC.

I'm new to the more scientific ways of naming what I've found. For the longest time I was happy just finding that beautiful shell. Then came the need to give them a name. Then when I found out there were not only wentletraps, but angulate, Humphreys, frosted, bladed, Champion's wentletraps etc., I knew I was in over my head!