Phylum: Mollusca Siliqua patula Class: Bivalvia; Heterodonta Order: Veneroida The flat razor clam Family: Pharidae Taxonomy: The familial designation of this (see Plate 397G, Coan and Valentich-Scott species has changed frequently over time. 2007). Previously in the Solenidae, current intertidal Body: (see Plate 29 Ricketts and Calvin guides include S. patula in the Pharidae (e.g., 1952; Fig 259 Kozloff 1993). Coan and Valentich-Scott 2007). The superfamily Solenacea includes infaunal soft Color: bottom dwelling bivalves and contains the two Interior: (see Fig 5, Pohlo 1963). families: Solenidae and Pharidae (= Exterior: Cultellidae, von Cosel 1993) (Remacha- Byssus: Trivino and Anadon 2006). In 1788, Dixon Gills: described S. patula from specimens collected Shell: The shell in S. patula is thin and with in Alaska (see Range) and Conrad described sharp (i.e., razor-like) edges and a thin profile the same species, under the name Solen (Fig. 4). Thin, long, fragile shell (Ricketts and nuttallii from specimens collected in the Calvin 1952), with gapes at both ends Columbia River in 1838 (Weymouth et al. (Haderlie and Abbott 1980). Shell smooth 1926). These names were later inside and out (Dixon 1789), elongate, rather synonymized, thus known synonyms for cylindrical and the length is about 2.5 times Siliqua patula include Solen nuttallii, the width. Solecurtus nuttallii. Occasionally, researchers Interior: Prominent internal vertical also indicate a subspecific epithet (e.g., rib extending from beak to margin (Haderlie Siliqua siliqua patula) or variations (e.g., and Abbott 1980). Siliqua patula var. nuttallii, based on rib Exterior: Both valves are similar and morphology, see Possible gape at both ends. The beaks are subcentral Misidentifications) (Oldroyd 1924). and toward anterior end, and the posterior end is round. Description Hinge: The hinge ligament is Size: Individuals up to 190 mm (Haderlie and completely external, and not seated on a Abbott 1980; Coan and Valentich-Scott 2007), nymph (Fig. 2). The left valve is with four with average size adults over 40 mm (Coan cardinal teeth, while the right valve is with two and Carlton 1975). (Fig. 2). A vertical or radial rib projects Color: Periostracum is smooth, brown, shiny, downward and anteriorly from hinge in both and lacquer-like (Ricketts and Calvin 1952). valves (Siliqua, Keen and Coan 1974) (Fig. The shell exterior is white, obscurely rayed, 2). with faint violet coloration and the interior is Eyes: also white, but tinged with violet and pink Foot: The foot in S. patula projects to a (Haderlie and Abbott 1980). length that is one half the total shell length General Morphology: Bivalve mollusks are and has a muscular flap (Haderlie and Abbott bilaterally symmetrical with two lateral valves 1980). It aids in digging by anchoring within or shells that are hinged dorsally and the sediment and contracting such that the surround a mantle, head, foot and viscera body is pulled downward (Ricketts and Calvin (see Plate 393B, Coan and Valentich-Scott 1952) (see Burrow and Behavior). 2007). Solenid and pharid bivalves are Siphons: Siphons are short and fused at the burrowers and some species are quite fast tips, except at the very end (Haderlie and (e.g., Siliqua patula, see description in this Abbott 1980) (Fig. 4). The exhalant and guide). They have shells that are longer than inhalant openings are ringed by tentacles. wide and often razor-like at the opening edge Hiebert, T.C. 2015. Siliqua patula. 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. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12920 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Burrow: A fast burrower, S. patula uses its S. patula (< 55 mm in length) and has an foot to anchor and muscular contractions to internal rib that is vertical and narrow and a pull body downward. Individuals can posterior end that is truncate. It has been completely bury itself within seven seconds suggested that S. lucida are simply young S. (Ricketts and Calvin 1952) and the burrowing patula individuals (Hertlein 1961), but this is speed allows them to avoid the reach of many not yet known. Siliqua lucida lives in clam diggers. Burrowing behavior leaves a protected bay sands and has concentric slight dimple in the sand at the surface (not brown bands on its exterior. Although unlike a thumb imprint). There is no variations in S. patula have been permanent burrow, unlike the similar species synonymized, occasionally readers will find Solen sicarius (see description in this guide) references to S. patula var. nuttallii, which is (Haderlie and Abbott 1980). Individuals orient more oval shape, with purple beaks and four vertically within the sediment (see Fig 3, hinge teeth in the left valve, not two (Oldroyd Pohlo 1963; Haderlie and Abbott 1980). 1924). Ensis myrae and Siliqua altra are offshore species and E. myrae is has a shell Possible Misidentifications that is long and thin. Solenidae and Pharidae are two razor clam Only two species, in the genus Solen, families represented locally and pharid are reported locally in the Solenidae, they genera were recently placed in the former have an almost straight dorsal margin, a family (see previous editions of this guide). terminal beak, and one cardinal tooth in each They are both characterized by cylindrical valve (Keen 1971). Solen rostiformis (= S. shells that are about 2.5 times as long as high rosaceus, but see Pohlo 1963; von Cosel and gape at both ends. They have no dorsal 1992) has a thin shell that tapers and a margin ears (compare to Pectinidae, see periostracum that is lighter than S. sicarius; it Plate 394E, Coan and Valentich-Scott 2007), is light olive green to brown in color. Solen a hinge with ligament that is entirely external rostiformis is a pink shelled clam and its and dorsal, equally shaped adductor muscle siphons are annulated (and it can regenerate scars (compare to Mytilus trossulus, this them when disturbed, Pohlo 1963). It lives in guide), and shells that do not have prominent sandier situations than does S. sicarius radial sculpturing (Coan and Valentich-Scott (Coan and Carlton 1975). Solen sicarius, on 2007). The difference between the two the other hand, has a thick shell, a blunt families is that members of the Pharidae have posterior (‘the blunt razor shell’) and a dark one shell valve with two cardinal teeth and the brown periostracum. Solen sicarius is found other with four, while the Solenidae have a occasionally in permanent burrows in mud or single cardinal tooth on each shell valve muddy sand (Kozloff 1974) and is the (Coan and Valentich-Scott 2007). Other local species most likely to be confused with razor-shaped clams besides the Solenidae Siliqua patula. It lacks an interior vertical rib such as the Mytiiidae include some genera and multiple hinge teeth, and is four times as (e.g. Adula) which are also long and long as wide, not 2.5 times, as in S. patula cylindrical. Adula (see A. californiensis, this (Keen and Coan 1974). Furthermore, the guide) are usually a boring species, however, profile in S. patula is much more oval, and having hairy posterodorsal slopes, a very not as cylindrical as in Solen sicarius. small anterior adductor scar, and no hinge One long, cylindrical bivalve of the teeth (Coan and Valentich-Scott 2007). family Solecurtidae, Tagelus californianus, Hiatellidae, including the geoduck, Panopea the jackknife clam, could be confused with generosa have large, quadrate, gaping Siliqua patula. It too has nearly central bivalves, without hinge teeth, and with nearly beaks, is about 2.5 times as long as wide, equal adductor muscle scars (Keen and Coan and gapes at both ends. It never has the 1974). internal strengthening rib of S. patula, Four species are reported locally in however, and its ligament is seated on a the Pharidae. Siliqua patula has an internal nymph or projection (as in Protothaca rib that slopes anteriorly, a wide and tapering staminea, see plate). Tagelus californianus posterior end. Siliqua lucida is smaller than is gray, has no lateral teeth, and has short Hiebert, T.C. 2015. Siliqua patula. 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. siphons (Coan and Carlton 1975). It is found Life-History Information below Humboldt Bay, California, in mudflats. Reproduction: Separate sexes with broadcast spawning and external fertilization. Ecological Information Females produce 6–10 million eggs. In Range: Siliqua patula was described from Washington, all individuals spawn suddenly individuals collected near Coal Harbor, Cook and simultaneously near the end of May or Inlet, Alaska (Weymouth et al. 1926). Known early June, when water temperatures rise range includes Aleutian Islands to Pismo (e.g., 13˚C, Fraser 1936; Ricketts and Calvin Beach, California, but individuals are 1952; Haderlie and Abbott 1980). However, uncommon in California (Weymouth et al. spawning is not sudden or simultaneous in 1931). Alaska or British Columbia, Canada, where Local Distribution: Coos Bay distribution at spawning occurs from July to August (Ricketts Pt. Adams spit near the mouth of the bay and and Calvin 1952; Bourne and Quayle 1970; usually on open coast. This species is more Breese and Robinson 1981, Lassuy and common in coastal regions with long stretches Simons 1989. Sperm morphology appears to of wide sandy beaches (e.g., Seaside, OR, characterize many veneroid taxa (see Fig.