Saxidomus Giganteus Class: Bivalvia; Heterodonta Order: Veneroida Beefsteak Clam, Butter, Or Washington Clam (Deshayes,1839) Family: Veneridae
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CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Oregon Scholars' Bank Phylum: Mollusca Saxidomus giganteus Class: Bivalvia; Heterodonta Order: Veneroida Beefsteak clam, butter, or Washington clam (Deshayes,1839) Family: Veneridae Description Ecological Information Size—adults average 3 inches, can be 4 (10 Range—Aleutians to Monterey, California; but cm). rare in the southern range. Color—whitish; can have blackish Distribution—bays and estuaries, rarely on discoloration; interior white; exterior open coast or inlets with oceanic influence sometimes tan, particularly young specimens. (Packard 1918). Exterior—shell oval (Coan and Carlton Habitat—mud or sand (Coan and Carlton 1975), posterior truncate (Keen and Coan 1975); gravelly beaches (Puget Sound) 1974); concentric, rough ribs close together, (Kozloff 1974a); cigar-shaped or deflated no radial lines (fig. 1); valves gape only figure eight-shaped hole, 1/2-3/4 inch long slightly at posterior end (gape less than 1/4 (Jacobson 1975) (1.2-2 cm). shell width) (Kozloff 1974a); can retract Temperature—prefers colder waters (see siphon, but not foots; valves very similar; shell range). thick, heavy: deep (fig. 2). Tidal Level—can be found down to 30 cm, Interior—valves similar: inner ventral margin (about 12 inches) from surface, but frequently smooth (Keen and Coan 1974), inner surface closer to surface (Kozloff 1974a). white "porcelaneous"; with subequal darker Associates—occasionally infested wan muscle scars. Pallial line continuous, not a Immature specimens of commensal pea crab series of scars (Kozloff 1974a), (but broken by Pinnixa littoralis; but usually free of parasites a sinus), fig. 3. Flesh often red: "beefsteak" (Ricketts and Calvin 1971). clam. Hinge—very heavy, posterior, external. Quantitative Information Ligament—external, seated on a long, Abundance—the most abundant clam on massive nymph (or chondrophore) (fig. 4). suitable beaches of the Northwest" (Ricketts Teeth—three cardinal hinge teeth, flanked by and Calvin 1971); exploited commercially long lateral tooth in each valve (fig. 4). (Puget Sound) (Kozloff 1974a). Possible Misidentifications Life History Information Saxidomus nuttalli, the larger, more Reproduction—pelagic larvae distributed by southern species, is found in California in the tidal currents much variation in spawning same habitat as S. giganteus, but apparently times, even in neighboring beds spawning does not extend into Oregon. (S. nuttalli is the water temperatures: 11.5°C-18°C: two weeks only Saxidomus in Humboldt Bay, however.) to veliger stage, four weeks to settle (Fraser Its shell is more elongate, the ribs heavier, and Smith 1928). Spawning in late summer. rougher and more conspicuous (Coan and tali (Puget Sound) (Fraser 1929). Carlton 1975); the interior is often marked Growth Rate—little growth in young after posteriorly with purple. There are no other settling, until following spring (Fraser and large ovate bivalves here with concentric ribs Smith 1928). and without radial ribs. Longevity—lives to 20 years or more (Morris Panopea generosa, the deep-burrowing et al. 1980). geoduck, is quadrate, and gapes widely. Food—feeds by straining material from the Tresus capax, the gaper clam, (family current of water that they pump through the Mactridae), is also quadrate, fairly smooth gills: filter feeder. and chalky white outside. The truncated Predators—sting rays, man, fishes, shore posterior gapes moderately. Its ligament is birds, drilling snails. Gulls will scavenge partly internal; its cardinal teeth are "A" discards. Most important food clam in British shaped; the shell has a dark, eroded partial Columbia (Morris et al. 1980). covering. Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected] Literature Cited 1. COAN, E. V., and J. T. CARLTON. 1975. Phylum Mollusca: Bivalvia, p. 543-578. In: Light's manual; intertidal invertebrates of the central California coast. S. F. Light, R. I. Smith, and J. T. Carlton (eds.). University of California Press, Berkeley. 2. FRASER, C.M. 1929. The spawning and free swimming larval periods of Saxidomus and Paphia. Transactions of the Royal Society of Canada. 23:195-198. 3. FRASER, C. M., and G. M. SMITH. 1928a. Notes on the ecology of the butter clam, Saxidomus giganteus. Transactions of the Royal Society of Canada. 22:271-286. 4. JACOBSON, R. W. H. P. H. K. S. 1975. Oregon's captivating clams. Oregon State University Extension Service, Sea Grant Marine Advisory Program, and Oregon Dept. of Fish and Wildlife, [Corvallis, Or.]. 5. KEEN, A. M., and E. COAN. 1974. Marine Molluscan Genera of Western North America: An Illustrated Key. Stanford University Press, Stanford, California. 6. KOZLOFF, E.N. 1974a. Keys to the marine invertebrates of Puget Sound, the San Juan Archipelago, and adjacent regions. University of Washington Press, Seattle & London. 7. PACKARD, E. L. 1918. Molluscan fauna from San Francisco Bay. 14:199-452. 8. RICKETTS, E. F., and J. CALVIN. 1971. Between Pacific tides. Stanford University Press, Stanford, California. Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected] Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected] .