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Cryptomya californica Phylum: Class: ; Order: Myoida False (Conrad, 1837) Family: Myidae

Description Size—to 30 mm long; this specimen 21 mm. distinguished internally by the presence of a Color—exterior chalky and white, with dull deep (Cryptomya has no sinus). reddish brown . Interior glossy There is only one local species: white with spoon-shaped tooth (right ): Mya arenaria, the soft-shelled clam in our orange. area, grows to 120 mm. Like Cryptomya, it is Shell Shape—oblong, gaping posteriorly. thin-shelled, white and fragile, and lives in Right valve more convex than left (McLean sandy mud. It is longer than Cryptomya (Keen 1969). Shell thin, fragile, with external thick 1971) however, and is found down to 30 cm periostracum and light concentric deep, and not necessarily near Callianassa (Quayle 1970). Beaks central, fairly prominent burrows. (fig. 1). —internal; in right valve, orange, Ecological Information leathery, corresponds with chondrophore in Range—Gulf of Alaska to northern Peru left valve. Ligament seated in a shallow (Keen 1971). resilifer (pit) (figs. 3, 4). Local Distribution—in bays where Interior—adductor muscle scars equal: family Callianassa or Upogebia beds are found: Myidae. Coos Bay, airport extension site, Pigeon —entire, forms a right angle Point, South Slough, etc.; Tillamook Bay; posteriorly (fig. 3). Netarts; Nestucca (Hancock et al 1979); also Pallial Sinus—absent (or inconspicuous): offshore. genus Cryptomya (fig. 3) (Coan and Carlton Habitat—sand and sandy mud, nearly always 1975). within its siphons' reach of the burrow of Hinge Area—no true teeth or hinge plate, Callianassa, the ghost shrimp (which in turn except for chondrophore and resilifer: family often inhabits beds). Myidae (McLean 1969). Salinity—collected at 30 ‰ salt. Chondrophore—broad, horizontal, Temperature—occurs over a wide range of projecting; in left valve only. Right valve with water temperatures geographically. resilifer to receive chondrophore. Tidal Level—can be found down to 20” below Siphons—short, oval, surrounded by surface (Quayle 1970); as well as the upper tentacles (incurrent). Excurrent a short to mid-intertidal range. vase-like siphon (fig. 6). Associates—the well-known association of Callianassa can include as well the polynoid Possible Misidentifications polychaete Hesperonoe, 3 different Cryptomya can be distinguished from other pinnotherid (pea) crabs, and the goby small white clams (Macoma, for instance) by Clevelandia ios. (Farther south the clam is its lack of any external ligament, the fragility of found next to Urechis burrows) (McLean its shell, and internally, by its lack of hinge 1969). It has also been found near the burrow teeth, and presence of the chondrophore in of the mud shrimp Upogebia. the left valve. Mactridae, including the gaper clam, have a chondrophore in both valves. Quantitative Information Mactridae adults are large, gape widely, and Weight— have small (which Myidae lack); Abundance—can be very common: in some their posterior edges are truncate, not parts of Coos Bay, it is the most abundant rounded, and their siphons are leather-like at bivalve (airport mudflat, North Bend) (Gonor the tips. et al 1979). The genus Mya, closely related, is quite common in the northwest, and be immediately Life History Information Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected] Reproduction— Growth Rate— Longevity— Food--filters material from water pumped in by Callianassa in the burrow. (Both Upogebia and Urechis are more effective detritus filterers than Callianassa, and Cryptomya does better, at Callianassa's table (MacGinitie and MacGinitie 1949). Predators—protected by the burrow. Behavior—stays not just below the surface as a short-siphoned clam of its size normally would, but deep in the substrate, where it burrows into Callianassa burrows.

Bibliography 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. GONOR, J. J., D. R. Strehlow, and G. E. Johnson. 1979. Ecological assessments at the North Bend airport extension site, p. vii, 163 p. School of Oceanography, Oregon State University, Salem, OR. 3. HANCOCK, D. R. et al. 1979. Subtidal clam populations: distribution, abundance, and ecology. Oregon State University, Sea Grant College Program, [Corvallis]. 4. KEEN, A. M. 1971. Sea shells of tropical west America; marine mollusks from Baja California to Peru. Stanford University Press, Stanford. 5. MACGINITIE, G. E., and N. MACGINITIE. 1949. Natural history of marine . McGraw-Hill Book Co., New York. 6. MCLEAN, J. H. 1969. Marine shells of southern California. [Los Angeles] Los Angeles County Museum of Natural History. 7. QUAYLE, D. B. 1970. The intertidal bivalves of British Columbia. British Columbia Provincial Museum, Victoria, Canada.

Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected]

Digitized 2010 – Last Updated 1979 – E-mail corrections to [email protected]