Shellfish Image Gallery Descriptions

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Corbicula Sp.

Appearance: Generally small in size, ranging from thumbnail to approximately one inch across. It is wide and round across the back; typically thin-walled  and dark brown with yellow or green bands on the outer edges. Do not confuse it with the mahogany clams.

Native Area: Asia

Typical Location: The clam is a very prolific freshwater shellfish, usually found in most streams and lakes. Large populations are known to exist in the Catawba River and its surrounding lakes.

Public Health Significance: This shellfish is not approved for harvesting for human consumption. Any of these shellfish found for sale in North Carolina must be considered adulterated and immediately removed from sale, disposed of or embargoed. North Carolina Wildlife Resources Commission rules do not allow taking of these clams in flowing waters and strictly limit the number that can be taken in impounded waters for use as fish bait.

Anadara granosa

Appearance: The blood arkshell clam is relatively small (up to 1 inch). Deep ridges radiate vertically from the hinge to teh shell edges with rough surfaces. Shells are white to cream colored with dark patches near the shell edges. The hinge area very straight. In its raw state, the viscera exhibit deep blood-red color (see last photo). They are ypically sold whole and frozen. These clams should not be confused with the ponderous arks also detailed in this gallery.

Native Area: These shellfish originate primarily from southeast Asia.

Public Health Significance: Not approved for consumption in the United States. As of 2005, Korea was the only Asian country that had adopted National Shellfish Sanitation Program guidelines and the only country to have its shellfish processors listed in the USFDA Interstate Certified Shellfish Shippers List (ICSSL). Any raw shellfish, including these blood arks, originating from countries not listed in the ICSSL should be deemed adulterated and disposed of or embargoed.

Mytilus edulis

Appearance: The shell surfaces are shiny bluish-black to black, usually measuring two to four inches in length. Blue mussels are a old-water species which are very temperature sensitive, often requiring storage temperatures near 32°F to maintain shelf life. Shells often gape open when left undisturbed and will typically close very slowly when agitated. They are typically sold live.

Typical Range: Routinely harvested from Northeast U.S. coast to Canada .

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Elliptio complanata

Appearance: The shells are dark brown, almost oval in shape, averaging 2-3 inches in length. The outer surface of the shell often flakes off, revealing a rough lighter-colored shell material underneath. They are typically sold live.

Typical Range: Freshwater mussel native to U.S., ranging from the southeastern U.S. to Canada. They are commonly found in North Carolina. Elliptio prefers streams and rivers to impounded waters.

Public Health Significance: As a freshwater species this shellfish is NOT approved for harvesting for human consumption. Because their habitat is in unapproved waters, there will typically not be a shellfish dealers tag associated with the product. These shellfish have been found in a restaurant in North Carolina, reportedly via seafood markets in New York City.

As a native freshwater shellfish, the N.C. Wildlife Resources Commission restricts any taking of these shellfish from flowing waters.

Panopea generosa

Appearance: The geoduck (pronounced goo-e-duck) is a very large clam, often exceeding well over one foot in length and four pounds in weight. The body and siphon are too large to be fully enclosed by the shells. Typically, the siphon is used in raw (sushi-type) dishes and the body, or viscera, of the clam is discarded. They are typically sold live.

Typical Range: Native to U.S. West Coast.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Mercenaria mercenaria

Appearance: The shell is heavy and fairly thick across the hinge. Numerous concentric lines are obvious on the shell surface and are especially evident near the hinge area. Sizes range greatly depending on the grade. Quahogs (pronounced kway-hog) can reach 6 inches in width, but more typically measure from 1 to 2 inches. The shells typically are dull gray to brownish in color. The meat (see photo 2 at left) is generally cream to pinkish in color. This is the most important North Carolina commercial shellfish species. Usually sold live, they may also be found shucked and canned.

Typical Range: Florida to Canada.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Artica islandica

Appearance: Marine clam, generally ranging in size from 1.5 to 2.5 inches across. Shell generally circular in shape, somewhat flattened, and dark brown in color. Hinge area may exhibit wear which reveals white shell material underneath, but shell surface does not typically peel or flake off as often seen in Asiatic clams also detailed in this gallery. Typically sold live.

Typical Range: Produced primarily in Northeast US and eastern Canada .

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Ruditapes philippinarum

Appearance: The Manila clam is a smaller clam, typically 1 inch in length. The shell is generally is cream colored with irregular lines radiating horizontally and vertically from the hinge area. It is similar to the hardshell clam, which is also detailed in this gallery, but the shell is not as rounded. The clam is mostly received in N.C. establishments from U.S. and Canadian sources. It is usually sold live.

Typical Range: Asia Pacific to US NW and Canda.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Crassostrea virginica

Appearance: The heavy, rough, irregular shell is typically 3-6 inches in length. Shells are usually dark gray to rust colored. The meat (see photo 2) is generally cream colored, however shell and meat color may vary depending on growing area conditions. Easterm oysters are frequently consumed raw, regularly served in restaurants and raw bars. They are regularly sold live as well as shucked.

Typical Range: Gulf of Mexico to Maine. Oysters are most widely harvested along the U.S. Gulf Coast.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Noetia ponderosa

Appearance: These bivalves have a heavy white shell which is deeply grooved. When alive, the shell is covered with a very thick deep brown to black layer that feels fuzzy to the touch. The hinge area is very predominant with a noticeable heart-shaped silhouette when viewed from either end.

The shells are usually much larger than those of the Asian blood arkshell clams (also described in this gallery), reaching up to 2.5 inches in width. This ark is also typically sold live. Commonly harvested in North Carolina during the process of harvesting Hardshell Clams.

Typical Range: Virginia to Texas.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Ensis directus

Appearance: Razor clams are typically five to seven inches in length with thin, curved shells. The shell has a shiny olive green outer covering with white underneath. Siphons will often protrude one to two inches out of shells when observed alive. They are usually sold live.

Typical Range: Inshore shellfish found from Labrador to Florida .

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Mya arenaria

Appearance: The shells are dull gray to whitish in color, with distinct uneven growth lines. They typically measure three to six inches in length. Shells do not touch at ends when closed (photo 2) and siphons will often protrude from the narrow end of the shells when observed live. The shell (at top) also displays a distinct raised "tooth" at the hinge.

Typical Range: Inshore shellfish found from Labrador to North Carolina, harvested primarily from Northeastern United States. Typically sold live.

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

Spisula solidissima

Appearance: The surf clam is a very large, heavy-bodied clam. Its shell measures up to seven inches in length. Coloration is olive brown to cream that may show wear at hinge revealing a cream-colored material underneath. This clam is yypically used for shucking and canning but occasionally sold live.

Typical Range: Ocean clam found commonly off the U.S. Atlantic coast from South Carolina to Nova Scotia .

Public Health Significance: Approved for human consumption if properly handled and labeled or tagged.

The first photo shows the underside of a fresh Canadian snow crab. Note the leech egg cases as well as live leeches located on the third leg. The second photo is a close up of the leech egg cases on the leg of a cooked Canadian snow crab.

Certain marine leeches deposit egg cases onto the outer surfaces of large crabs, such as snow crabs, in order to facilitate dispersal and protection for the young leeches. Neither the leeches or egg cases penetrate the shell surfaces. The egg cases can occasionally survive cooking intact as seen in photo 2, however the cooking and freezing process to which snow crabs shipped to the US are typically exposed destroys the delicate eggs inside.

Although unattractive to the eye, any such egg cases observed on cooked crabs pose no known public health risks to consumers and do not affect the health, quality, or taste of the crab meat.

Molluscan shellfish are prolific filter feeding organisms. They can filter great quantities of water through their gills each day and can accumulate constituents of the water column in high concentrations. Occasionally, algae concentrations in surrounding waters increase, which can result in the staining of shellfish gill tissues in unusual colors.

The first photograph compares the viscera of two oysters. The one on the left displays the normal, cream colored gills commonly seen in oysters. The oyster on the right displays gills that have been stained a blue-green color due to increased levels of naturally occurring blue-green algae in its growing area.

The second picture is a close-up of the gill tissue stained by blue-green algae. This often occurs in both clams and oysters harvested in North Carolina during the late winter when blue-green algae concentrations often rise. As algae concentrations decline the gill staining will disappear.

This condition routinely results in consumer concerns but has no effect on the health, quality and taste of the shellfish nor does this condition adversely affect the health of consumers. It is interesting to note that in France, a country known for oyster production, oysters with algae-stained gill tissues are a highly-sought after product.

A common condition affecting oysters from Massachusetts to the Gulf of Mexico is the appearance of black areas along the perimeter of the inner sides of the shells. These areas, commonly referred to as "Mud Blisters" are caused by the occurrence of a small worm, Polydora websteri.

This worm, which is typically less than 0.75 inches in length, lives between the mantle (outer most oyster tissue) and the inner shell surface in order to be protected from predators. The worms form blister-like chambers on the oyster shells, which often fill with mud creating the appearance of blisters.

The worms and "blisters" do not effect oyster health, quality or taste and they have no detrimental effects on consumers.

Oyster beds or reefs are very productive marine habitats providing shelter and subsistence to a wide variety of organisms. Many species of marine worms can often be found living on the outer surfaces of oyster shells. Worms are often found inside small calcareous tubes they form on the shell surfaces as well inside the natural crevices of the shells.

These worms can vary greatly in size, but typically do not exceed two inches in length. (The first photograph shows a mud worm often found on unwashed oyster shells while the second photo represents a variety of worms that may be found on the outer surface of oyster shells).

When oysters are shipped with no or minimal washing worms will routinely remain associated with the outside of oyster shells. Occasionally cleaned oysters will also retain some live worms that are enclosed in tubes or inside crevices.

When live oysters are roughly handled, as in cleaning and preparing at food service establishments, any associated worms will often make an appearance. To consumers not accustomed to seeing these organisms this can often cause considerable concern.

Such worms are generally not parasitic to oysters or any other organisms and are merely associated with oyster shells for protection. They do not affect the health, quality or taste of oysters, and they do not pose a known health risk to consumers, especially if they are discarded when found.

To help avoid concerns with such worms, oysters should be obtained from suppliers that thoroughly clean the oysters prior to shipment. Oysters should also be washed in cold, clean, running water prior to serving as an added step, and any worms that are found should be removed and discarded.

Pinnotheres ostreum

Occasionally, when a live oyster or mussel is opened or "shucked" a small, bug-like organism is found inside the shell. This organism is commonly called a Pea Crab (Pinnotheres ostreum). This small crab, typically less than half an inch in length is soft-bodied and lives inside oyster shells for protection as well as for food particles which are discarded by the oyster.

This crab is generally not harmful to the oyster with which it lives, but at times can cause damage to the oyster's gills as it moves around inside the shell. The crabs are generally cream colored with large red spots, but may turn an orange color if the oysters are cooked prior to opening.

The crabs present no known adverse effects on quality or taste of oysters nor on the health of consumers.