Brandon Corder, USA
Info
Paleoecological, archaeological, and modern shellfish records have shown that people in what is now British Columbia, Canada, increasingly used the robust shellfish populations for food during the early to late Holocene, and even began building shellfish gardens (tidal terraces with stone walls).
According to many sources, the butter clam Saxidomus giganteus is a highly prized recreational clam species and is mainly farmed in Canada and, to a lesser extent, in the USA.
Edible.
In the sea, it burrows into the substrate to a depth of up to 30 cm along the middle to lower tidal zones.
Description: This common tidal mussel has a large, black outer hinge band and well-developed concentric ribs, but no radial ribs.
The shell is only slightly longer than it is high, and the periostracum, if present, is neither yellow nor shiny.
The valves have a smooth but not shiny inner surface with a mantle sinus and a continuous mantle line.
The outer surface of the shell may be white or discolored by iron sulfide in oxygen-free sediments.
The siphons are moderately long (approx. 4 cm), united, and have black tips.
Distinguishing features from similar species:
Of the mussels commonly found on the same sheltered beaches, the cockle Clinocardium nuttallii (Conrad, 1837) has radial ribs and a wavy opening where the two valves meet.
The gaper clam Tresus capax (A. A. Gould, 1850) and the soft-shell clam Mya arenaria Linnaeus, 1758 have a large chondrophore at the hinge, and Tresus capax also has a large opening at the rear end.
The bentnose clam Macoma nasuta (Conrad, 1837) has valves that curve to the right at the rear end.
The littleneck clam Leukoma staminea (Conrad, 1837) has fine radial ribs, a row of small teeth on the inside of the valves near their ventral edges, and may also have a spotted pattern.
Source: Walla Walla University
Warning:
Consumption of poisonous razor clams (Saxidomus gigantea) is currently the most common cause of paralytic shellfish poisoning (PSP), of which saxitoxin is the most potent, in coastal communities in Alaska!
The poisoning occurs mainly in the summer months and is caused by the dinoflagellate Alexandrium catenella.
The bioaccumulation of PSTs in marine mammals, birds, and fish can be fatal and lead to mass deaths of wildlife and disruptions in the food web.
When toxin concentrations are particularly high, commercial fishing in the US is even temporarily suspended.
Environmental factors trigger the unchecked growth of these dinoflagellates.
Commercial and non-commercial harvesters remove the siphons completely or partially to reduce the toxicity of the mussel.
There are no known cases of human fatalities, but toxins accumulate in human organs, so here too, “the amount (of mussels consumed) makes the poison.”
The poison can hardly be destroyed by heating and boiling.
See the report “Paralytic shellfish poisoning toxins in butter clams (Saxidomus gigantea) from the Kodiak Archipelago, Alaska,” which we have linked below.
There is no risk of poisoning for aquarists who keep the mussel in a saltwater aquarium to filter the water.
Synonyms:
Saxidomus giganteus (Deshayes, 1839) · unaccepted (incorrect gender ending;...)
Saxidomus giganteus var. brevis Dall, 1916 · unaccepted > junior subjective synonym
Venerupis gigantea Deshayes, 1839 · unaccepted
Venus maxima R. A. Philippi, 1846 · unaccepted
According to many sources, the butter clam Saxidomus giganteus is a highly prized recreational clam species and is mainly farmed in Canada and, to a lesser extent, in the USA.
Edible.
In the sea, it burrows into the substrate to a depth of up to 30 cm along the middle to lower tidal zones.
Description: This common tidal mussel has a large, black outer hinge band and well-developed concentric ribs, but no radial ribs.
The shell is only slightly longer than it is high, and the periostracum, if present, is neither yellow nor shiny.
The valves have a smooth but not shiny inner surface with a mantle sinus and a continuous mantle line.
The outer surface of the shell may be white or discolored by iron sulfide in oxygen-free sediments.
The siphons are moderately long (approx. 4 cm), united, and have black tips.
Distinguishing features from similar species:
Of the mussels commonly found on the same sheltered beaches, the cockle Clinocardium nuttallii (Conrad, 1837) has radial ribs and a wavy opening where the two valves meet.
The gaper clam Tresus capax (A. A. Gould, 1850) and the soft-shell clam Mya arenaria Linnaeus, 1758 have a large chondrophore at the hinge, and Tresus capax also has a large opening at the rear end.
The bentnose clam Macoma nasuta (Conrad, 1837) has valves that curve to the right at the rear end.
The littleneck clam Leukoma staminea (Conrad, 1837) has fine radial ribs, a row of small teeth on the inside of the valves near their ventral edges, and may also have a spotted pattern.
Source: Walla Walla University
Warning:
Consumption of poisonous razor clams (Saxidomus gigantea) is currently the most common cause of paralytic shellfish poisoning (PSP), of which saxitoxin is the most potent, in coastal communities in Alaska!
The poisoning occurs mainly in the summer months and is caused by the dinoflagellate Alexandrium catenella.
The bioaccumulation of PSTs in marine mammals, birds, and fish can be fatal and lead to mass deaths of wildlife and disruptions in the food web.
When toxin concentrations are particularly high, commercial fishing in the US is even temporarily suspended.
Environmental factors trigger the unchecked growth of these dinoflagellates.
Commercial and non-commercial harvesters remove the siphons completely or partially to reduce the toxicity of the mussel.
There are no known cases of human fatalities, but toxins accumulate in human organs, so here too, “the amount (of mussels consumed) makes the poison.”
The poison can hardly be destroyed by heating and boiling.
See the report “Paralytic shellfish poisoning toxins in butter clams (Saxidomus gigantea) from the Kodiak Archipelago, Alaska,” which we have linked below.
There is no risk of poisoning for aquarists who keep the mussel in a saltwater aquarium to filter the water.
Synonyms:
Saxidomus giganteus (Deshayes, 1839) · unaccepted (incorrect gender ending;...)
Saxidomus giganteus var. brevis Dall, 1916 · unaccepted > junior subjective synonym
Venerupis gigantea Deshayes, 1839 · unaccepted
Venus maxima R. A. Philippi, 1846 · unaccepted
