Phylum: Mollusca Clinocardium nuttallii Class: Bivalvia, Heterodonta, Euheterodonta Order: Cardiida Basket of heart cockle Family: Cardioidea, Cardiidae, Clinocardiinae Taxonomy: This species was originally de- and consist of 30 ridges. The complex intes- scribed as Cardium nuttallii (named after the tine is with 11 loops and the total length (from zoologist, Thomas Nuttall) by Conrad in crystalline style to exit from visceral mass) is 1837. Cardium was later split into several 300 mm (Schneider 1994). For diagram of groups and C. nuttallii was moved to the ge- internal anatomy see Schneider 1994. nus Clinocardium, which was designated by Exterior: Keen in 1936 (Kafanov 1980; Schneider Byssus: 2002). Other known synonyms include Car- Gills: Gills are filibranch type, and are dium californianum and Cardium corbis (e.g. strongly plicated and fused to a siphonal sep- Fraser 1931; Weymouth and Thompson tum posteriorly (Bernard and Noakes 1990; 1931). The distinctive shell morphology of Schneider 1994). The outer demibranch Clinocardium (with some associated sub- bears 53–120 plicae (each plica comprises 40 genera, see Kafanov 1980) is distinct within filaments), while the inner has 75–110 the subfamily Clinocardiinae (Karanov (Schneider 1994). The gills in many suspen- 1980). Taxonomy of the group is based sion feeding bivalves are elongated and fold- largely on stomach and shell morphology ed to increase filtering surface area (Barnard (Schneider 1994, 1995). and Noakes 1990). Shell: When viewed from the side (left or right Description valve), the shell is triangular, but when viewed Size: Individuals up to 72 mm (Packard from either end it is heart-shaped (Fig. 3) 1918), but often grows to greater size, par- (hence “heart cockle”, Kozloff 1993). Usually ticularly on northern beaches (Fraser 1931), approximately 34 ribs radiate outward from where they can be up to 100 mm (Kozloff the shell umbo (fig. 1) and are crossed with 1993). concentric growth lines (Haderlie and Abbott Color: Warm brown when young and mott- 1980). led. Adults are light brown (Kozloff 1993). Interior: White, but not pearly. The General Morphology: Bivalve mollusks are anterior and posterior muscle scars equal in bilaterally symmetrical with two lateral valves area (compare to Adula californiensis, this or shells that are hinged dorsally and sur- guide) and pallial line is simple. Known for its round a mantle, head, foot and viscera (see large foot and short siphon. Shell of C. Plate 393B, Coan and Valentich-Scott californiense is composed of three layers 2007). Cariids have distinctly inflated shells including an inner layer that is cross-laminar, and central beaks, which is not seen in any middle complex cross laminar, and outer that other bivalve family (Kozloff 1993; Coan and is prismatic in structure (Zhang et al. 2014). Valentich-Scott 2007). Exterior: Shell as high as long (Kozloff Body: (see Fig. 298, Kozloff 1993) 1974), or higher with individuals generally Color: longer than wide during first year (Length: an- Interior: Ligament is entirely dorsal, terior to posterior) (Fraser 1931). Valves are and not internal. Labial palps are triangular A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Clinocardium nuttallii. 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. alike, and shell is inflated, triangular, and Possible Misidentifications with rounded corners (Kozloff 1974). Shell The taxonomy (especially among high- thick, but rather brittle (Keep and Longstreth er-level taxa) of family Cardiidae, or cockles, 1935). The posterior end is evenly rounded has been thoroughly studied due to the di- and smooth. The umbones are prominent verse morphology and good fossil record (see (Abbott 1968), beaks nearly central and di- Schneider 1992, 1994, 1995, 2002). It con- rected anteriorly (Keen and Coan 1974) (Fig. tains one to four species locally and C. nut- 2). tallii is the only species included in most re- Hinge: Hinge is central, with one cent keys (Coan and Valentich-Scott 2007). strong cardinal tooth, and an anterior and The family is within the Hederodonta and, as posterior lateral tooth in each valve (Fig. 2). such, possesses few hinge teeth and is char- Eyes: Bears numerous, tiny eyes on optical acterized by ovate and inflated shells with tentacles on mantle margin (Haderlie and central beaks, hinges with lateral teeth, shell Abbott 1980). sculpture that is with radial ribs, a hinge liga- Foot: Foot enables excellent digging ment that is entirely external (see Plate 397B, (Ricketts and Calvin 1952; Coan and Valen- Coan and Valentich-Scott 2007). They have tich-Scott 2007). The large and strong foot shells that are generally not cemented to the can be used to push and flip the entire body substratum and a dorsal margin that is without (e.g., to escape predation from Pycnopodia ears (Coan and Valentich-Scott 2007). No helianthoides, Kozloff 1993; Pisaster other bivalve family has such an inflated shell brevispinus, Haderlie and Abbott 1980). and central beaks. Siphons: No siphon tubes. Instead, si- Clinocardium blandum is an offshore phons are simply holes in the mantle margin species, with distribution from Sonoma coun- that allow for only a shallow burrow (Ricketts ty, California northward, Nemocardium centifi- and Calvin 1952). Clinocardium nuttallii has losum is also an offshore species and Trachy- 60 mantle tentacles, which are largely pre- cardium quadragenarium is a southern spe- sent dorsal to the excurrent siphon opening cies, known from southern California to Mon- and extend to top of posterior adductor mus- terey, California (Coan and Valentich-Scott cles (Schneider 1994). 2007). Nemocardium, with few extant spe- Burrow: Shallow burrow is within 1 mm of cies, has a prominent shell sculpture, with surface (Ricketts and Calvin 1952; Chang posterior ribs only and an otherwise smooth and Levings 1989), so that the posterior end surface (see Fig. 5, ter Poorten 2013). of the individual is situated just below the sediment (Kozloff 1993). Burrowing time is Ecological Information slowed (up to two-fold) in sediments bearing Range: Type locality is the Columbia River seagrass roots and/or invertebrate tubes estuary in Oregon. Japan, Alaska and south (Brenchley 1982), however, a greater densi- along Pacific coast to San Diego (Weymouth ty of C. nuttallii was observed in mudflats and Thompson 1931; Haderlie and Abbott that had eelgrass (Zostera marina) than 1980). Fossils from the family Cardiidae are those that did not (Galleher et al. 2012). If found along the north Pacific and European buried less than 50 mm (e.g., by dredging), subarctic, and date to the Cenozoic (Kafanov C. nuttallii can open its siphon to filter feed 1980). after 24 hrs (Chang and Levings 1989). Local Distribution: Local distribution near bay mouths on tideflats in most Oregon estu- aries as well as on exposed beaches south of A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Oregon (Weymouth and Thompson 1931). Reproduction: Simultaneous hermaphrodit- Habitat: Beaches of uniform, but not very ism has been observed in this species coarse sand (Fraser 1931; ”corn meal sand”, (Edmondson 1920; Fraser 1931; Gallucci and Packard 1918; Ricketts and Calvin 1952). Gallucci 1982). Spawning occurs annually Often found in exposed beaches. from June–Oct in Oregon, April-Nov in San Clinocardium nuttallii occur in diverse habi- Juan Island (Haderlie and Abbott 1980; Garri- tats from exposed sandy beaches to fine son Bay, Gallucci and Gallucci 1982; Yaquina bay sand (Fraser 1931), and large and Tillamook Bays, Oregon, Robinson and populations can be found in eelgrass/mud Breese 1982; Kabat and O’Foighil 1987), and areas (Kozloff 1993). June and July in British Columbia, Canada Salinity: Not found in upper bays where sa- (Fraser 1931). Oocytes are 80 µm in diame- linities vary greatly. ter and are surrounded by a jelly layer that is Temperature: 50 µm thick. Sperm are motile for up to 2 Tidal Level: High and mid intertidal to deep hours (at 4˚C, Liu et al. 2008). Complete de- waters, up to 200 m offshore in sandy areas scription of gametogenesis see Gallucci and or bays (Haderlie and Abbott 1980; Coan Gallucci 1982. and Valentich-Scott 2007). Larva: Bivalve development generally pro- Associates: Small specimens are often host ceeds from external fertilization via broadcast to young Pinnixa faba or P. littoralis (pea spawning through a ciliated trochophore stage crabs) (Ricketts and Calvin 1971; Haderlie to a veliger larva. Bivalve veligers are charac- and Abbott 1980). Mantle, siphon, and foot terized by a ciliated velum that is used for tissue of individuals older than two years, swimming, feeding and respiration. The veli- found to house the green endosymbiotic ger larva is also found in many gastropod lar- alga, zoochlorellae (e.g. Chlorella), with a vae, but the larvae in the two groups can be commensal or parasitic relationship suggest- recognized by shell morphology (i.e. snail-like ed (Cooke 1975; Hartman and Pratt 1976; versus clam-like). In bivalves, the initial Jones and Jacobs 1992; Soo and Todd shelled-larva is called a D-stage or straight- 2014). hinge veliger due to the “D” shaped shell. Abundance: Not as abundant as other mol- This initial shell is called a prodissoconch I lusks (e.g., Saxidomus, Protothaca, British and is followed by a prodissoconch II, or shell Columbia, Canada, Fraser 1931). This spe- that is subsequently added to the initial shell cies is the most abundant of its family on the zone.