Mya Arenaria Class: Bivalvia; Heterodonta Order: Myoida Soft-Shelled Clam Family: Myidae

Home , Heterodonta, Mya (bivalve), Myidae, Nautilus (genus), Pallial sinus, Prodissoconch

Phylum: Mollusca Mya arenaria Class: Bivalvia; Heterodonta Order: Myoida Soft-shelled clam Family: Myidae

Taxonomy: Mya arenaria is this species cilia allow the style to rotate and press against original name and is almost exclusively used a gastric shield within the stomach, aiding in currently. However, the taxonomic history of digestion (Lawry 1987). In M. arenaria, the this species includes many synonyms, crystalline style can be regenerated after 74 overlapping descriptions, and/or subspecies days (Haderlie and Abbott 1980) and may (e.g. Mya hemphilli, Mya arenomya arenaria, contribute to the clam’s ability to live without Winckworth 1930; Bernard 1979). The oxygen for extended periods of time (Ricketts subgenera of Mya (Mya mya, Mya arenomya) and Calvin 1952). The ligament is white, were based on the presence or absence of a strong, and entirely internal (Kozloff 1993). subumbonal groove on the left valve and the Two types of gland cells (bacillary and goblet) morphology of the pallial sinus and pallial line comprise the pedal aperture gland or (see Bernard 1979). glandular cushion located within the pedal gape. It is situated adjacent to each of the Description two mantle margins and aids in the formation Size: Individuals range in size from 2–150 of pseudofeces from burrow sediments; the mm (Jacobson et al. 1975; Haderlie and structure of these glands may be of Abbott 1980; Kozloff 1993; Maximovich and phylogenetic relevance (Norenburg and Guerassimova 2003) and are, on average, Ferraris 1992). 50–100 mm (Fig. 1). Mean weight and length Exterior: were 74 grams and 8 cm (respectively) in Byssus: Wexford, Ireland (Cross et al. 2012). Gills: Individual weight varies seasonally and is Shell: Shell is soft, thin, fragile (hence “soft greatest just before spawning and the shell clam”, Kozloff 1993; Coan and smallest just after (range, 100–200 mg ash- Valentich-Scott 2007), and composed free dry weight, Wadden Sea, Zwarts 1991). completely of aragonite (MacDonald and Color: White with gray or dark, yellowish Thomas 1980). The valves have an oval and brown periostracum on shell edges, creating rounded anterior and a pointed posterior a rough outermost layer. Siphons are dark (Kozloff 1993) and gape at each end (Haderlie and Abbott 1980; Kozloff 1993; see (Haderlie and Abbott 1980). External shell Fig. 3, Zhang et al. 2012) sculpture is with concentric rings (Fig. 1). General Morphology: Bivalve mollusks are Interior: Deep pallial sinus and bilaterally symmetrical with two lateral valves spoon-shaped chondrophore, or triangular or shells that are hinged dorsally and projection, is present on the left valve only surround a mantle, head, foot and viscera (Haderlie and Abbott 1980; Kozloff 1993). (see Plate 393B, Coan and Valentich-Scott Left and right adductor muscle scars are the 2007). Myoid bivalves are burrowers and same size but very different in shape (Fig. 2). borers, with long siphons and hinges with few Exterior: Left and right valves are of teeth (Coan and Valentich-Scott 2007). similar morphology, which is long and egg- Body: Body is egg-shaped in outline (Fig. 1; shaped, with shells convex, thin and brittle Ricketts and Calvin 1952) (see Fig. 305, (Fig. 4). Low concentric growth striae on Kozloff 1993). anterior and posterior ends are different: Color: anterior are more blunt and posterior are Interior: A crystalline style (consisting pointed, but both ends gaping (Packard of a gelatinous cortex and liquid core, Lawry 1918). Beaks small, bent posteriorly, and 1987) resides in a sac lined with cilia. The slightly anterior of center (Fig. 2).

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12910 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hinge: Valve areas dissimilar and periostracum. It also bores into rock and hard with spoon-shaped chondrophore in left valve. clay while M. arenaria and C. californica Right valve is with tooth in opposition to burrow into sand or mud. The shells of the chondrophore (Fig. 3). No hinge plate teeth two latter species are relatively thin. In M. (cardinal or lateral). arenaria, the pallial sinus is deep and Eyes: individuals reach sizes of 150 mm, while in C. Foot: californica the pallial sinus is shallow, Siphons: Long, large siphons are fused, inconspicuous and individuals tend to be non-retractable (Coan and Valentich-Scott smaller (30 mm) (Coan and Valentich-Scott 2007; Tan and Beal 2015), and dark in color 2007). Mya arenaria is found as deep as 40 (Haderlie and Abbott 1980). cm and is not necessarily near Callianassa Burrow: Unlike the other local member of the californiensis burrows, where one might find Myidae, Cryptomya californica (see Cryptomya californica. The siphons are M. description in this guide), M. arenaria has arenaria are also longer than those of C. long siphons and can be found in relatively californica (see C. californica, Figs. 1, 6 in this deep burrows up to 40 cm (Haderlie and guide). Additionally, Sphenia luticola is a myid Abbott 1980; Kozloff 1993; Coan and species that may occur in our area, but is Valentich-Scott 2007; González et al. 2015). found offshore in rocks and within kelp holdfasts (Coan and Valentich-Scott 2007). Possible Misidentifications Juvenile Mya are not easily distinguished There are five bivalve subclasses based on from Sphenia species, but Mya can be morphology and fossil evidence and one of recognized by a large continuous pallial sinus those is the diverse Heterodonta. Recent (Coan 1999). molecular evidence (18S and 28S rRNA) Mya arenaria may be confused with suggests that the heterodont order Myoida is other local common clams, e.g. Saxidomus, non monophyletic (Taylor et al. 2007). The Tresus, Tellina or Macoma species. These family Myidae includes 25–40 species genera do not have an internal ligament or a worldwide, which can be divided into groups chondrophore. Small Tresus can otherwise such as those that are burrowing (Mya), those be mistaken for M. arenaria. Small Tellinid that are attached to shells or stone (Sphenia) clams have an external ligament without a or those utilizing the burrows of other species nymph, and lateral hinge teeth, which M. (Cryptomya, Paramya) (Zhang et al. 2012). arenaria lack. Macoma species (see Characters of the Myidae include a shell that descriptions in this guide) are very like is not cemented to the substratum, valves that Tellina, but their shells are always a bit are (relatively) morphologically similar, a flexed, they have no lateral teeth, and no dorsal margin without ears, a hinge with an internal coloration. Furthermore, where M. internal ligament in a distinct resilifer or arenaria is abundant is in upper reaches of chondrophore that is spoon shaped and estuaries where salinity is reduced, species present on the left valve (Coan and Valentich- in the genera Saxidomus and Tresus are not Scott 2007). Cryptomya species are usually found. characterized by hinge without tooth-like process anteriorly on the right valve. Mya, on Ecological Information the other hand, have thin shells, gaping Range: Type locality is Europe (Zhang et al. anteriorly and posteriorly and commarginal 2012). Current eastern Pacific distribution growth lines (Zhang et al. 2012). from Alaska to San Diego, California (Haderlie There are only three local myid and Abbott 1980). Current populations species including Platyodon cancellatus, Mya introduced from the Atlantic coast with oyster arenaria and Cryptomya californica (“the false spat in 1874 in San Francisco (Coan and Mya” see description in this guide). Platydon Valentich-Scott 2007), although it appears in cancellatus can be distinguished from the the fossil record (Ricketts and Calvin 1971) in latter two species because its shells are California and Vancouver (Packard 1918). heavy and with wavy commarginal sculpture However, M. arenaria is not represented in and a round anterior. It has a truncate, local Native American mounds (Kozloff 1993). gaping posterior end covered with The palaeontological history of M. arenaria Hiebert, T.C. 2015. Mya arenaria. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. was described by Fujie (1957, 1962), as the (Clements and Hunt 2014). Thermal stress species originated in the Pacific in the (e.g., associated with climate change) is Miocene, spread to the Atlantic into the accompanied by oxidative stress in marine Pliocene, became extinct in the Pacific mollusks, including M. arenaria, and leads to northwest by the Pleistocene was re- the mitochondrial production of reactive established and introduced from Atlantic oxygen species (Abele et al. 2002). Mya populations in 1880s and was re-introduced arenaria individuals respond to hypoxia by to the eastern Atlantic and Pacific during the reducing burrow depth and increasing siphon Pleistocene (Rasmussen and Heard 1995; extension (Taylor and Eggleston 2000). Zhang et al. 2012). Following introduction, M. Salinity: Tolerates brackish water and arenaria spread northward to Willapa Bay, reduced salinity, as well as full salt water Washington in 1880 and Alaska in 1950s (Haderlie and Abbott 1980; Kozloff 1993). (Haderlie and Abbott 1980; Ricketts and Temperature: Range limited to cool areas, Calvin 1952). Common on the Atlantic Coast although this species can also tolerate and Europe in areas of low salinity (e.g. Baltic temperatures below freezing (Ricketts and Sea, Kozloff 1993). It has crowded out the Calvin 1952). Eastern Atlantic southern native Macoma spp. on the Pacific coast in distribution set by critical maximum some areas (Keep and Longstreth 1935). In temperature of 28˚C (Rasmussen and Heard the Cold Temperate Northwest Atlantic 1995). biogeographic province, six genetic clusters Tidal Level: Found from 15–40 cm depths in of M. arenaria were observed spanning seven mud habitats (Packard 1918) and intertidal to distinct ecoregions. Those to the north were 20 m (Zhang et al. 2012). defined by geographic barriers and selection Associates: Commensal pea crabs, Fabia processes and those to the south were likely subquadrata, F. concharum, Pinnixa faba, P. the result of and increased with geographic littoralis (Ricketts and Calvin 1971; Haderlie distance only (St-Onge et al. 2013). and Abbott 1980). Co-occurs with Macoma Local Distribution: Local distribution in balthica and the lugworm, Arenicola marina, Coos and Yaquina Bay as well as the in the Wadden Sea (Günther 1992; Strasser Suislaw, Umpqua, Tillamook, Alsea and et al. 1999). The abundance of A. marina, a Columbia estuaries. bioturbator, has a negative effect on Habitat: Mud and sand of bays with sand, recruitment in M arenaria (Strasser et al. mud, gravel mix (Kozloff 1993; Coan and 1999). Domoic acid (a neurotoxin), released Valentich-Scott 2007), often in upper reaches from and ingested with the diatom Pseudo- where salinity is reduced, but requires nitzschia, is biodegraded in M. arenaria with complete protection, as it cannot burrow or the help of autochthonous bacteria (Stewart maintain itself in a shifting substratum et al. 1998). (Ricketts and Calvin 1971). Very tolerant of Abundance: Mya arenaria can be very extreme conditions (e.g., anaerobic or foul abundant and often occurs with a patchy mud, brackish water, temperatures below distribution (e.g., 177 individuals/m2, St. freezing, Ricketts and Calvin 1971; Haderlie Lawrence estuary, Roseberry et al. 1992). and Abbott 1980). Can live without oxygen Locally abundant in Yaquina, Siuslaw, and for eight days (Ricketts and Calvin 1952) and Umpqua estuaries, and in some parts of Coos it is thought that the shell serves as an Bay where it is “fairly common” (Haderlie and alkaline reserve to neutralize lactic acid from Abbott 1980). Mya arenaria was reported as anaerobic respiration (Haderlie and Abbott ubiquitous in northeast and northwest Atlantic 1980). In a study testing the effects ocean (Tan and Beal 2015). In the Wadden Sea, 50 acidification on M. arenaria, sedimentary individuals/m2were observed (Strasser et al. aragonite saturation resulted in a negative 1999; Günther 1992), and up to 1,000 relationship with dispersal and a positive individuals/m2reported in Kandalaksha Bay, relationship with clam burrowing depth White Sea (Maximovich and Guerassimova (Clements and Hunt 2014). Conversely, 2003). This common estuarine species is increases in proton concentration yielded a often used in toxicity and biomarker tests, negative relationship with burrowing depth where effects of tributyltin (TBT) included

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12910 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] masculinizing of females, sex ratios skewed Larva: Bivalve development generally toward male, and delayed male maturation proceeds from external fertilization via (Gagné et al. 2003). broadcast spawning through a ciliated trochophore stage to a veliger larva. Bivalve Life-History Information veligers are characterized by a ciliated velum Reproduction: Dioecious with, at most, two that is used for swimming, feeding and periods of sexual maturation and spawning, respiration. The veliger larva is also found in one in the fall (primary maturation period) and many gastropod larvae, but the larvae in the one in spring (secondary maturation) two groups can be recognized by shell (Chesapeake Bay and St. Lawrence estuary, morphology (i.e. snail-like versus clam-like). Roseberry et al. 1992). A continuous In bivalves, the initial shelled-larva is called a reproductive period from April to October D-stage or straight-hinge veliger due to the occurs in New England (Pfitzenmeyer and “D” shaped shell. This initial shell is called a Shuster 1960). Atlantic species tend to prodissoconch I and is followed by a spawn from June to August and eggs 60–80 prodissoconch II, or shell that is subsequently µm diameter (Haderlie and Abbott 1980). In added to the initial shell zone. Finally, shell Cape Cod, gametogenesis began during late secreted following metamorphosis is simply winter and spawning was complete by the referred to as the dissoconch (see Fig. 2, end of summer (September, Ropes and Brink 2001). Once the larva develops a foot, Stickney 1965). Populations in Wexford, usually just before metamorphosis and loss of Ireland had sex ratios of 1:1.15 (female to the velum, it is called a pediveliger (see Fig. male) and were ripe and spawning in August, 1, Kabat and O’Foighil 1987; Brink 2001). completed in November (Cross et al. 2012). (For generalized life cycle see Fig. 1, Brink Life-history characteristics appeared to 2001.). Young M. arenaria larvae (150 µm) correlate along a latitudinal gradient in the have a broadly rounded umbo with a short, northeast coast of the United States: sloping posterior (see Fig. 4, Brink 2001). individuals in southern populations grew The umbo becomes angled in advanced faster, exhibited greater variation in juvenile individuals and the shoulders become straight mortality, had larger egg sizes (range 25–45 and steeply sloping. Eventually, the anterior µm), lower egg density (range 495–1,541), and posterior ends elongate and are pointed decreased longevity (4–15 years), and larger and metamorphosis occurs when larvae are size at maturation (see Table 1, Appeldoorn 170–230 µm (Chanley and Andrews 1971; 1995). In San Francisco, CA, Brink 2001). Settlement in the Wadden Sea gametogenesis began in late February and occurs from May to June (Günther 1992) and spawning occurred from April to October in Mill Cove, New Brunswick, when individuals (Rosenblum and Niesen 1985). Sperm are greater than 500 µm (Morse and Hunt morphology and spermatogenesis of the 2013). Settlement may depend on sediment subspecies Mya arenaria oonogai was properties (e.g., grain size, presence of sea described by Kim et al. in 2011. In this grasses, Strasser et al. 1999). Juveniles and species, the spermatozoon was smaller individuals (< 2 mm) can also be approximately 50 µm in length. Disseminated transported hydrodynamically (Hunt and neoplasia, a leukemia-like disease, occurs in Mullineaux 2002). Maximum transport rates the gonadal tissues of M. arenaria (Barber coincided (positive correlation) with peaks in 1996; Boettger and Barletta 2015). The bedload transport: in sheltered sandflats, frequency of neoplasia increases in spring in maximum transport rate was 790 Maine (Boettger and Barletta 2015). In 1994 individuals/m/day and in exposed habitats, in Whiting Bay, Maine, progressive and maximum transport rate increased to 2,600 potentially lethal gonadal neoplasms were individuals/m/day (Emerson and Grant 1991). observed in 19% of individuals, involving up Recruitment is highly variable and based on to 100% of gonadal follicles. Females were (among others) predation, temperature, and more likely to have neoplasms than males adult-larval interactions. Some research and produced fewer, smaller gametes leading shows that larvae avoid settlement in areas to an overall negative impact on reproductive with high conspecific density (Maximovich and output (Barber 1996). Hiebert, T.C. 2015. Mya arenaria. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. Guerassimova 2003, but see Brousseau and deposition occurred from March to November Bagilvo 1988; Günter 1992). in Gloucester, MA (Brousseau 1979). Juvenile: Juveniles are typically less than Although external growth rings can be 2–15 mm in length (Strasser et al. 1999; Tan conspicuous, they may not be an accurate and Beal 2015) and size is generally fixed by indicator of clam age and are not always epibenthic predators. Sexual maturity occurs clearly defined. Instead, internal growth lines, when individuals are 25–35 mm in length which can be seen in thin sections when (Brousseau 1979; Rosenblum and Niesen shells are sliced from the umbo to the ventral 1985). Following settlement, significant margin, reliably indicate growth in late spring changes occur in population distributions months before spawning (Prince Edward within the first month, due to post-settlement Island, MacDonald and Thomas 1980). The dispersal and predation (Morse and Hunt neoplastic disease, disseminated neoplasia, 2013). Newly settled individuals and juveniles which is characterized by excessive and are prey to a variety of epipenthic predators abnormal cell growth is found in M. arenaria and their size and abundance is ultimately and appears to be transmitted among controlled by predation (Hunt and Mullineaux populations by horizontal transmission 2002). Mortality by predation significantly (Carballal et al. 2015). decreases with growth. For example, green Food: A suspension and filter feeder (Tan crabs (Carcinus maenas) reduced 80% of and Beal 2015), M. arenaria takes up oxygen, small (<17 mm) M. arenaria in caged food, algae, and detritus containing iron (Fe) experiments containing 1–5 crabs in Pompuet and other trace metals (González et al. 2015) Harbour, Nova Scotia (Floyd and Williams by filtering seawater. Compared to other filter 2004). Young M. arenaria (< 30 mm) were feeders, M. arenaria may have a low filtration most susceptible to predation by the snail, rate (Jorgensen 1966 in Vincent et al. 1988). Lanutia heros, as 3.5% died/year in the first Individuals can adapt to varying algal five years (Maine, Commito 1982). concentrations; a low concentration leads to a Ultimately, size selective feeding leads to reduced siphon opening and valve gape, overestimated average size measurements which can occur after several hours of among juveniles and fast juvenile growth reduced concentrations, while an increase in allows for a size refuge from epibenthic algal concentration leads to siphon opening predators (Wadden Sea, Günther 1992). within 5–20 min (Riisgard et al. 2003). Additionally, juveniles escape predation with Predators: Shorebirds (e.g., sea gulls), sea severe winters that result in mortality of otters eat exposed adults and larvae are predators (Günther 1992). Mortality preyed upon by planktonic predators and significantly decreased 94 days after suspension feeders. Adults are prey to settlement (Günther 1992). infaunal predators (e.g., gastropods, Longevity: Up to 28 years (Appeldoorn nemerteans) and juveniles live so close to the 1995). A 17 years maximum was reported in sediment surface that their siphons are often Kandalasksha Bay, White Sea (Maximovich nipped off by crustaceans and fish (Tan and and Guerassimova 2003). Over 25 years of Beal 2015). Additional predators include fish, monitoring in the White Sea, populations of shrimp, sandworms, crabs (e.g., the green M. arenaria showed alternatively high and low crab, Carcinus maenas, Wong 2013; Morse levels of mortality (Table 2, Gerasimova et al. and Hunt 2013; Tan and Beal 2015, the blue 2015). The authors attributed this variation in crab (C. sapidus, Taylor and Eggleston 2000), mortality to the unstable habitat early in life snails (Cross et al. 2012), the stingray, and intraspecific relationships and Dasyatis sabina (Rasmussen and Heard competition associated with dense 1995), and Nereis virens (Morse and Hunt aggregations (Gerasimova et al. 2015). 2013). Predation by Polinices duplicatus, Growth Rate: Clams as small as 25 mm increased with temperature, with individuals have been found to have mature gametes ingesting as many as 96 Mya (Pfitzenmeyer and Shuster 1965). Individuals arenaria/snail/year (Edwards and Huebner approximately 15 mm in length grew 110 µm 1977). Carcinus maenas (green crab) per day (Günther 1992). Most shell populations decrease populations of M.

Hiebert, T.C. 2015. Mya arenaria. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. 16. COMMITO, J. A. 1982. Effects of 24. GERASIMOVA, A. V., N. V. Lunatia heros predation on the MAXIMOVICH, and N. A. FILIPPOVA. population dynamics of Mya arenaria 2015. Cohort life tables for a and Macoma balthica in Maine, USA. population of the soft-shell clam, Mya Marine Biology. 69:187-193. arenaria L., in the White Sea. 17. CROSS, M. E., S. LYNCH, A. Helgoland Marine Research. 69:147- WHITAKER, R. M. O' RIORDAN, and 158. S. C. CULLOTY. 2012. The 25. GONZALEZ, P. M., D. ABELE, and S. reproductive biology of the softshell PUNTARULO. 2015. Oxidative status clam, Mya arenaria, in Ireland, and the of respiratory tissues of the bivalve possible impacts of climate variability. Mya arenaria after exposure to excess Journal of Marine Biology. 2012:1-9. dissolved iron. Marine and Freshwater 18. EDWARDS, D. C., and J. D. Behaviour and Physiology. 48:103- HUEBNER. 1977. Feeding and growth 116. rates of Polinices duplicatus preying 26. GUNTHER, C. P. 1992. Settlement on Mya arenaria at Barnstable Harbor, and recruitment of Mya arenaria (L.) in Massachusetts. Ecology. 58:1218- the Wadden Sea. Journal of 1236. Experimental Marine Biology and 19. EMERSON, C. W., and J. GRANT. Ecology. 159:203-215. 1991. The control of soft-shell clam 27. HADERLIE, E. C., and D. P. ABBOTT. (Mya arenaria) recruitment on 1980. Bivalvia: the clams and allies, p. intertidal sandflats by bedload 355-410. In: Intertidal invertebrates of sediment transport. Limnology and California. R. H. Morris, D. P. Abbott, Oceanography. 36:1288-1300. and E. C. Haderlie (eds.). Stanford 20. FLOYD, T., and J. WILLIAMS. 2004. University Press, California. Impact of green crab (Carcinus 28. HUNT, H. L., and L. S. MULLINEAUX. maenas L.) predation on a population 2002. The roles of predation and of soft-shell clams (Mya arenaria L.) in postlarval transport in recruitment of the Southern Gulf of St. Lawrence. the soft shell clam (Mya arenaria). Journal of Shellfish Research. 23:457- Limnology and Oceanography. 462. 47:151-164. 21. FUJIE, T. 1957. On the myarian 29. JACOBSON, R. W., P. HEIKKILA, and pelecypods of Japan. Part I: Summary K. S. HILDERBRAND. 1975. Oregon's of the study of the genus Mya from captivating clams. Oregon State Hokkaido. Journal of the Faculty of University Extension Service, Sea Science Hokkaido University Geology. Grant Marine Advisory Program, and 9:381-413. Oregon Dept. of Fish and Wildlife, 22. —. 1962. On the myarian pelecypods Corvallis, Or. of Japan. Part II: Geological and 30. KABAT, A. R., and D. O'FOIGHIL. geographical distribution of fossil and 1987. Phylum Mollusca, Class recent species, genus Mya. Journal of Bivalvia, p. 309-353. In: Reproduction the Faculty of Science Hokkaido and development of marine University Geology. 11:399-430. invertebrates of the northern Pacific 23. GAGNE, F., C. BLAISE, J. PELLERIN, Coast. M. F. Strathmann (ed.). E. PELLETIER, M. DOUVILLE, S. University of Washington Press, GAUTHIER-CLERC, and L. VIGLINO. Seattle, WA. 2003. Sex alteration in soft-shell clams 31. KEEP, J., and J. LONGSTRETH. (Mya arenaria) in an intertidal zone of 1935. West coast shells: a description the Saint Lawrence River (Quebec, in familiar terms of the principal Canada). Comparative Biochemistry marine, fresh-water, and land mollusks and Physiology: C-Toxicology & of the United States, British Columbia, Pharmacology. 134:189-198. and Alaska, found west of the Sierra.

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