Zirfaea Pilsbryi Class: Bivalvia, Heterodonta, Euheterodonta

Home , Barnea (bivalve), Barnea candida, Cyrtopleura, Cyrtopleura costata, Pholas, Xylophaga

Zirfaea pilsbryi Class: Bivalvia, Heterodonta, Euheterodonta

Order: Imparidentia, Myida The rough piddock Family: Pholadoidea, Pholadidae, Pholadinae

Taxonomy: The taxonomies of both pholad 2007). Myoid bivalves are burrowers and bor- species in this guide (Z. pilsbryi and Penitel- ers, with long siphons and hinges with few la penita) are extensive and complicated, teeth (Coan and Valentich-Scott 2007). Mem- including many synonyms and overlapping bers of the Pholadidae bore into a variety of descriptions (for full list of synonymies see substrates, possess no pallets on siphon tips Kennedy 1974). Zirfaea pilsbryi was origi- and have an anterior end that is pointed or nally described as Z. gabbii, a species even- curved with no notch (contrast to Teredinidae tually moved to the genus Penitella (see P. species, e.g., Bankia setacea, this guide) (see gabbii, Kennedy 1974). Lowe renamed and Plate 427F, 430D, Coan and Valentich-Scott described Z. pilbsryi in 1931. Thus, these 2007). While most pholad species are inter- three species names (Z. pilsbryi, Z. gabbii, tidal or subtidal, some can be found boring and P. gabbii) and the subspecies designa- into wood at great depths (e.g., 7,250 meters tion, Z. gabbii femii (Adegoke 1967 in Ken- Xylophaga, Kennedy 1974; Reft and Voight nedy 1974), are common synonyms, with 2009; Voight 2009; Marshall and Spencer descriptions that overlap and are specific to 2013). original author (see Kennedy 1974). Body: (see Plate 297, Ricketts and Calvin 1952; Fig 361, Kozloff 1993). Description Color: Size: Individuals up to 150 mm in length Interior: (Ricketts and Calvin 1971; Haderlie and Ab- Exterior: bott 1980; Kozloff 1993) and may be the Byssus: largest of the boring species (Ricketts and Gills: Calvin 1971). Coos Bay (Fossil Point) Shell: Gapes widely at both ends and valves specimens were approximately 75–125 mm have ventral marginal groove (Fig. 2). Anteri- long. or end has rasping ridges, but posterior is with Color: White exterior, interior also white or smooth, concentric lines (Haderlie and Abbott light salmon (Turner 1954; Haderlie and 1980; Kozloff 1993). Anterior end of shell is Abbott 1980). Siphons gray-white to ivory, not as prominently demarcated from the pos- speckled with very small (1.5–2 mm) orange terior (compare to Penitella penita, this guide). chitinous spots, dark red around siphonal Shell is relatively fragile as it gains ample pro- openings and incurrent cirri (Fig. 1). Foot tection from its surrounding burrow (Ricketts and mantle are ivory in color, when and Calvin 1952). preserved (Turner 1954). Periostracum is Interior: The groove separating anteri- dark brown (Haderlie and Abbott 1980). or and posterior sections of valve (or umbonal General Morphology: Bivalve mollusks are ventral sulcus) is conspicuous in juveniles, but bilaterally symmetrical with two lateral almost disappears near ventral margin in valves or shells that are hinged dorsally and older specimens (Kennedy 1974) (Fig. 1). surround a mantle, head, foot and viscera Strong muscle scars present, but no hinge or (see Plate 393B, Coan and Valentich-Scott

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. Zirfaea pilsbryi. 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.

ligament (Pholadidae, Quayle 1970). Pallial drical burrow. While burrowing, individuals sinus is broad and deep, extending nearly to exude particles out the inhalant siphon by umbo (Fig. 3). The apophysis (or contracting their body quickly (Ricketts and myophore) is broad, with rounded spoon- Calvin 1952; Haderlie and Abbott 1980). Thir- shaped end (Fig. 3). ty-two movements make for one entire revolu- Exterior: Shape hard, solid, elon- tion, which takes a total of 70 minutes and af- gate, oval, but not globose. Valves divided ter each revolution, the rotating direction alter- into two regions: anterior triangular and pos- nates (MacGinitie in Ricketts and Calvin terior is rounded with concentric rings (Fig. 1952). Burrows may be pear-shaped 1). Anterior is triangular with rough file-like (producing Gastrochaenolites-type traces, radial and concentric denticulations, which Furlong et al. 2014) rather than cone-shaped, can project into spines on anterior margin and individuals often do not fit as tightly within (Fig. 1). Rasping portion covers half total their burrows as other pholads (Evans and valve area (Kozloff 1993). No callum is pre- Fisher 1966). (see also Habitat and Behav- sent (calcareous anterior accessory plate, ior.) see Penitella penita, this guide), only a pro- Pholadidae-specific character tective membrane. Umbonal reflection is Mesoplax: There is only one mesoplax (or wide. The anterior ventral edge of valve is small accessory dorsal plate) present in this strongly angled (Fig. 1). The posterior por- species. It is weak and reduced (Evans and tion is with concentric striations only and is Fisher 1966) and with a transverse basal rounded to truncate (Fig. 1). Gapes extend flange that well-developed in juvenile (Fig. to the middle of the shell (Keen and Coan 4a), but becomes less obvious in adults (Fig. 1974). 4b). (Note: the mesoplax is often lost in col- Hinge: lecting.) Eyes: Foot: Foot is round and truncate (Turner Possible Misidentifications 1954). There are several families of burrow- Siphons: Fused and very long (6–8 times ing clams and the Pholadidae can be distin- the shell length) and can extend 15 cm guished by their distinctively marked body ar- above the burrow surface (Haderlie and Ab- eas. Members of the Teredinidae and Phola- bott 1980). They are non-retractible and didae can be found locally. They can be dis- covered with small chitinous discs, but with- tinguished by the absence of pallets on si- out papillae or pustules. No siphonoplax phon tips in the latter family as well as an an- (flaps around siphon, see Penitella penita, terior end that is not notched, as in the Tere- this guide). Periostracum extends from over dinidae. The Pholadidae includes 10 species 1/3 shell posterior to cover part of siphons locally, within the following genera: Barnea (Quayle 1970). (B. subtruncata), Chaceia (C. ovoidea), Burrow: Zirfaea pilsbryi burrows into heavy Netastoma (N. rostratum), Parapholas (P. cal- mud, clay and shale to 50 cm depths. The ifornica), Penitella (five local species) and foot is sucker-like and attaches to the sub- Zirfaea (Z. pilsbryi). The genus Zirfaea is strate so that the shell can rotate slowly and characterized by adults that burrow into sand create a cylindrical burrow. Shell valves or mud, the absence of a callum in mature in- rock back and forth by contractions of anteri- dividuals, and a shell sculpture that is divided or and posterior adductor muscles. Individu- into two distinct zones (see Plates 427C, als rotate after each stroke, making a cylin- 429D, Coan and Valentich-Scott 2007). The 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]

genus Barnea, for example, also lacks a cal- ventral edge, but unlike Zirfaea, P. turnerae lum, but does not have these two distinct has a callum. Penitella richardsoni (=gabbi, zones. All other local genera are character- Kennedy 1989) is also small (up to 75 mm) ized by the presence of a callum and all ex- with a warty, creamy-lemon colored siphon cept Netastoma have a myopore as well. and it is not common. It is different from the Parapholas species have shell sculpture other members of this genus as its umbone with three distinct zones, where members of reflection is not appressed to the anterior end, Chaceia and Pentilla have two. a character also found in C. ovoidea. Penite- The genus closest to Zirfaea, and lla richardsoni differs from C. ovoidea by ha- most likely to be confused with it, is Penitel- ving a callum that does not gap and an more la. As mentioned above, Penitella’s valves elongated shell (Coan and Valentich-Scott are also divided into two distinct sections, 2007). A new species of Penitella, P. hopkin- but it differs in having a calcareous anterior si, was described from Alaska, but it not yet callum, or accessory plate (in the adult) as reported in our area (Kennedy and Armen- well as a posterior which gapes only at the trout 1989). With adult specimens, it should end, not to the middle of the shell (it has no be easy to tell Zirfaea from Penitella by its anterior gape) and the apophysis is narrow, long, non-retractable siphon and by the mem- not broad. No Penitella species has a braneous covering of the anterior, instead of a siphon longer than its body (Evans and calcareous callum. Small shells without the Fisher 1966) and all Penitella species have callum could be young Penitella as well as retractable siphons. There are five species mature Zirfaea and size at maturity varies of Penitella in our area (see Coan and greatly with environmental condition. Valentich-Scott 2007). Zirfaea crispata is a small Atlantic Penitella conradi is very small and is species without chitinous spots on the found in Mytilus or Haliotus (abalone) shells. siphons. It may have been introduced into It has a siphonoplax lined with coarse granu- Humboldt Bay, California with eastern oyster les (Zirfaea has no siphonoplax) (Evans and spat Crassostrea (Turner 1954), but is not Fisher 1966) and can bore into nephrite currently included in local intertidal guides (Monterey, California, Wilson and Kennedy (see Coan and Valentich-Scott 2007). 1984). Penitella penita (see description in Ecological Information this guide) has a heavy membraneous sip- Range: Type locality is Bolinas Bay, Califor- honoplax, a calcified callum and a distinctive nia (Turner 1954). Eastern Pacific distribution mesoplax. Its anterior rasping surface co- includes the Bering Sea to Baja, California vers less than half the valve area (Kozloff (Ricketts and Calvin 1952; Haderlie and Ab- 1974). It can be up to 70 mm in length. Pe- bott 1980). Zirfaea pilsbryi is the most com- nitella fitchi also has a heavy siphonoplax, mon fossil pholadid on the Pacific coast and but has a callum with a gap. This is a rare dates from the Pleistocene in California and species, found low in the intertidal and up to northern Baja California (for pholad palaeoe- 25 meters deep. Penitella turnerae is larger cology see Kennedy 1974, 1993). than P. penita (to 125 mm), and less com- Local Distribution: Coos Bay distribution at mon. It is stout, and like Zirfaea lacks a sip- South Slough, Fossil Point, Tillamook Bay, honoplax. It has a distinctive, rounded me- Netarts Bay, Yaquina Bay (Turner 1954) and soplax, however, and its long, white, retrac- Siuslaw River (Hancock et al. 1979). table siphons are tipped with solid red. Like Habitat: Zirfaea pilsbryi bores into shale, clay, Zirfaea, it has a strongly angled anterior

sand or mud, as soft rock, to depth of 25–35 translucent white and 45–46.8 µm in diameter cm (Turner 1954), where mud and clay are (33˚C, Turner and Johnson 1968; 21˚C, Boyle preferred substrates (Coan and Valentich- and Turner 1976). Scott 2007), but individuals are sometimes Larva: Bivalve development generally pro- seen in outside rocky reefs (Ricketts and ceeds from external fertilization via broadcast Calvin 1952). In one case, individuals were spawning through a ciliated trochophore stage seen burrowing into wood (Emerson 1951). to a veliger larva. However, in the deep water Substrate type (e.g., hard versus soft) has pholad genus, Xylophaga, species brood lar- been shown to alter the piddock shell shape, vae until late veliger stages (Kennedy 1974; size and hardness (see Tajima and Kondo Voight 2009). Bivalve veligers are character- 2003). Piddock burrows have the ability, ized by a ciliated velum that is used for swim- particularly when individuals are present in ming, feeding and respiration. The veliger lar- large numbers, of compromising the stability va is also found in many gastropod larvae, but of shorelines throughout their lifetimes (e.g., the larvae in the two groups can be recog- Pholas dactylus, Barnea candida, B. parva, nized by shell morphology (i.e. snail-like ver- Pinn et al. 2005). sus clam-like). In bivalves, the initial shelled- Salinity: larva is called a D-stage or straight-hinge veli- Temperature: Cold to temperate waters. ger due to the “D” shaped shell. This initial Tidal Level: Intertidal to deep water (Quayle shell is called a prodissoconch I and is fol- 1970), below -0.3 meters (Kozloff 1993) lowed by a prodissoconch II, or shell that is Associates: Associates include other nestl- subsequently added to the initial shell zone. ing and burrowing clams (e.g., Penitella, Finally, shell secreted following metamorpho- Hiatella, Entodesma, Adula) as well as the sis is simply referred to as the dissoconch commensal pea crab, Opisthopus (see Fig. 2, Brink 2001). Once the larva de- transversus, and the flat-worm Cryptophallus velops a foot, usually just before metamor- magnus (MacGinitie 1935; Haderlie and phosis and loss of the velum, it is called a Abbott 1980). pediveliger (Kabat and O’Foighil 1987; Brink Abundance: Can be quite dense in locally 2001). (For generalized life cycle see Fig. 1, suitable conditions. This species is the third Brink 2001). Larvae of the common, local most abundant pholad at Fossil Point, Coos pholad, P. penita, are free swimming with a Bay (following Penitella penita, P. richard- pelagic duration of two weeks (Haderlie and soni, Evans and Fisher 1966). Abbott 1980). The development of other pholads (e.g., Barnea truncata, Chanley 1965; Life-History Information Cyrtopleura costata, Chanley and Andrews Reproduction: Spawning occurred in July in 1971; Martesia striata, Boyle and Turber southern California (MacGinitie 1935), but 1976) proceeds as planktotrophic veliger lar- little is known about the reproduction and vae. After 24 hours, M. striata larvae are development of this species. Breeding straight hinge veligers (68 µm in length and occurs in the congener, Z. crispata, in from 59 µm in height, Boyle and Turner 1976). Af- March through October (Northumberland ter eight days, they are umbo larvae (129–224 coast, United Kingdom, Allen 1969). Boyle µm) and they are pediveligers by 28–32 days and Turner (1976) described the (224–236 µm) post fertilization. Metamorpho- reproduction and development of the east sis in M. striata occurs after 48-53 days (see coast pholad, Martesia striata. This species Table 1, Figure 1, Boyle and Turner 1976). spawns in February and eggs are (see also Campos and Ramorino 1990 for

planktonic pholad larvae from Chile). The west. A. Shanks (ed.). Oregon State Uni- development of Z. subconstricta was fol- versity Press, Corvallis, OR. lowed by Ito (2005) where D-stage larvae 4. CAMPOS, B., and L. RAMORINO. 1990. were 70 µm in length and 60 µm in height Larvae and postlarvae of Pholadacea from and later stages were uniformly round and Chile (Mollusca, Bivalvia). Revista de Bio- 150–200 µm in diameter. Metamorphosis logia Marina. 25:15-64. occurred after five weeks and shells became 5. CHANLEY, P. E. 1965. Larval develop- asymmetrical once individuals were approxi- ment of a boring clam, Barnea truncata. mately 320 µm (see Fig. 1, Ito 2005). Chesapeake Science. 6:162-166. Juvenile: 6. CHANLEY, P. E., and J. D. ANDREWS. Longevity: 7–8 years (MacGinitie and Mac- 1971. Aids for identification of bivalve lar- Ginitie 1947; Ricketts and Calvin 1952). vae of Virginia. Malacologia. 11:45-119. The lifespan of the congener, Z. crispata is 5 7. COAN, E. V., and P. VALENTICH-SCOTT. –7 years (Allen 1969). 2007. Bivalvia, p. 807-859. In: The Light Growth Rate: Animals grow throughout and Smith manual: intertidal invertebrates their entire life, unlike Penitella species (see from central California to Oregon. J. T. Behavior). Growth rate of the congener, Z. Carlton (ed.). University of California crispata, is 8 mm/year (Allen 1969). Press, Berkeley, CA. Food: A suspension feeder, Z. pilsbryi uses 8. EMERSON, W. K. 1951. An unusual habi- its inhalant siphon to filter food through very tat for Zirfaea pilsbryi (Mollusca: VIADER). large gills that extend into the exposed si- Bulletin of the Southern California Acade- phon (Haderlie and Abbott 1980). my of Sciences. 50:89-91. Predators: Flatworms. 9. EVANS, J. W., and D. FISHER. 1966. A Behavior: Zirfaea pilsbryi is unusual among new species of Penitella (family Phola- pholads for its indeterminate growth, as an didae) from Coos Bay, Oregon. The Veli- individual remains an active burrower for its ger. 8:222-224. entire life and does not stop and seal its 10. FURLONG, C. M., M. K. GINGRAS, and J. shell with a callum when mature (MacGinitie ZONNEVELD. 2015. Trypanites-type ich- 1935). nofacies at the Bay of Fundy, Nova Scotia, Canada. Palaios. 30:258-271. Bibliography 11. HADERLIE, E. C. 1980. Stone boring ma- 1. ALLEN, J. A. 1969. Observations on size rine bivalves from Monterey Bay, Califor- composition and breeding of Northum- nia. Veliger. 22:345-354. berland populations of Zirphaea crispata 12. HADERLIE, E. C., and D. P. ABBOTT. (Pholadidae: Bivalvia). Marine Biology. 1980. Bivalvia: the clams and allies, p. 355 3:269-275. -410. In: Intertidal invertebrates of Califor- 2. BOYLE, P. J., and R. D. TURNER. 1976. nia. R. H. Morris, D. P. Abbott, and E. C. Larval development of wood boring pid- Haderlie (eds.). Stanford University Press, dock Martesia striata (L.) (Mollusca: Bi- California. valvia: Pholadidae). Journal of Experi- 13. HANCOCK, D. R., T. F. GAUMER, G. B. mental Marine Biology and Ecology. WILLEKE, G. P. ROBART, and J. FLYNN. 22:55-68. 1979. Subtidal clam populations: distribu- 3. BRINK, L. A. 2001. Mollusca: Bivalvia, p. tion, abundance, and ecology. Oregon 129-149. In: Identification guide to larval State University, Sea Grant College Pro- marine invertebrates of the Pacific North- gram, Corvallis.

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33. TURNER, R. D., and A. C. JOHNSON. 1968. Biology of marine wood-boring mollusks, p. 259-301. In: Marine borers, fungi and fouling organisms of wood. E. B. G. Jones and S. K. Eltringham (eds.). Organization for Economic Cooperation and Development, Paris. 34. VOIGHT, J. R. 2009. Diversity and reproduction of near-shore vs offshore wood- boring bivalves (Pholadidae: Xylophagai- nae) of the deep eastern Pacific Ocean, with three new species. Journal of Mol- luscan Studies. 75:167-174. 35. WILSON, E. C., and G. L. KENNEDY. 1984. The boring clam, Penitella conradi, (Bivalvia: Pholadidae) in nephrite from Monterey County, California. Nautilus. 98:159-162. Updated 2015 T.C. Hiebert