This individual species account is the most recent version of this book chapter.  Earlier iterations are contained in the first, second and third full editions of this work which are housed in Scholars' Bank.  Future editions of this work will be hosted by the Oregon Institute of Marine Biology.  Contact oimb@uoregon.edu for additional information

Hiebert, Terra C.

Meyer, Kirstin

University of Oregon Scholars' Bank

 Hiebert, T.C. 2014. Abarenicola pacifica. 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.       Description Size: Individuals often over 10 cm long and 1 cm wide.  Present specimen is approximately 4 cm in length (from South Slough of Coos Bay).  On the West coast, average length is 15 cm (Ricketts and Calvin 1971). Color: Head and abdomen orange, body a mixture of yellow, green and brown with parapodial areas and branchiae red (Kozloff 1993). General Morphology: A sedentary polychaete with worm-like, cylindrical body that tapers at both ends.  Conspicuous segmentation, with segments wider than they are long and with no anterior appendages (Ruppert et al. 2004).  Individuals can be identified by their green color, bulbous pharynx (Fig. 1), large branchial gills (Fig. 2) and a J-shaped burrow marked at the surface with distinctive coiled fecal castings (Kozloff 1993). Body: The body of arenicolids can be divided into three regions based on the presence or absence of branchiae. Anterior: A non-retractile prostomium is without appendages (Blake and Ruff 2007, Fig. 2).  Anterior prebranchial region of six setigers without branchiae and with strong setigerous annuli. Trunk: Posterior to the prebranchial region is a medial branchial region with large branchial gills from setigers seven to 19 (13 pairs).  Thoracic epidermis very thick, strongly aerolated (Fauchald 1977). Posterior: Caudal region is apodous, asetigerous and without appendages.  The pygidium tapers gradually to anus, no appendages (Fig. 2). Parapodia: (Fig. 3) Segments 1–19 with reduced noto- and neuropodia that are    reddish and are far from the lateral line.  All parapodia are absent in the caudal region. Setae (chaetae): (Fig. 3) Bundles of notosetae arise from notopodia near branchiae.  Short neurosetae extend along  neuropodium.  Setae present on segments 1-19 only (Blake and Ruff 2007). Eyes/Eyespots: None. Anterior Appendages: None. Branchiae: Prominent and thickly tufted in branchial region with bunched setae.  Hemoglobin makes the branchiae appear bright red (Kozloff 1993). Burrow/Tube: Firm, mucus impregnated burrows are up to 40 cm long, with typical fecal castings at tail end.  Head end of burrow is collapsed as worm continually consumes mud (Healy and Wells 1959).  Water is pumped through burrow by pulsating movements of the body (Ruppert et al. 2004). Pharynx: Thin-walled pharynx is simple and used for continually feeding on sediment.  Pharynx described as a large, eversible sack with mucus glands called buccal papillae (Healy and Wells 1959) (Fig. 1). Genitalia: Nephridia: Five pairs of nephridia are naked (without hoods) and situated between parapodia on segments 5–9 (Fig. 2).  They are sometimes difficult to observe.  Abarenicola specific characters Esophageal caeca: Dissection is necessary to identify Abarenicola species.  Abarenicola pacifica is distinct in having esophageal caeca comprised of one large anterior pair and 3–6 smaller pairs (Blake and Ruff 2007, Fig. 4).  Possible Misidentifications Other Arenicolidae have the same bushy gills in the middle third of the body.  Only the genus Abarenicola has well-separated Abarenicola pacifica The lugworm, or sand worm   Phylum: Annelida       Class:   Polychaeta        Order: Capitellida  Family: Arenicolidae     A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12654 and full 3rd edition: http://hdl.handle.net/1794/18839  Email corrections to oimbref@uoregon.edu  Hiebert, T.C. 2014. Abarenicola pacifica. 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. neuropodia, a non-retractile prostomium, more than one pair of esophageal caeca, and five pairs of nephridiopores.  Both Arenicola marina and pusilla have been found in Oregon estuaries.  Abarenicola claparedii oceanica, has hooded nephridial pores and esophageal caeca composed of 7–9 smaller pairs. Abarenicola vagabunda, from Puget Sound (but possibly from Oregon) (Oglesby  1973), is usually larger and dark brown.  It too, has hooded nephridial pores, and smaller esophageal caeca (11–18). Finally, the burrows of A. vagabunda are less permanent than A. pacifica's, are found in deep sand and may be more subtidal (Hobson 1966).  Ecological Information Range: Type locality is Puget Sound (Healy and Wells, 1959).  Known range includes Humboldt Bay, California to Alaska, Japan. Local Distribution: A north Pacific form and the most common lugworm (family Arenicolidae) in Puget Sound area intertidally (Hobson 1966).  Found in Coos Bay from estuary mouth to Coos River mouth (marker 15) and at Sunset Bay (Oglesby 1973). Habitat: Individuals build substantial L- or J- shaped burrows in sand and mud, mixed gravel or mud sediments (South Slough of Coos Bay) (Kozloff 1974).  Abarenicola pacifica tolerates a muddier, less permeable, more poorly sorted sediment than does A. c. vagabunda (Hobson 1966), but does not live in very soft mud (Porch 1970). Salinity: This species is not found in waters of low salinity or in heavily polluted anaerobic conditions (Porch 1970), but is an osmoconformer and can tolerate a wide range of salinities (lower salinity limit 17.5) (Oglesby 1973). Temperature: No information is available on temperature tolerance, though temperature fluctuation between 6 and 16° C has been found to significantly affect feeding rate (Hymel and Plante 2000). Tidal Level: Individuals are common intertidally, but no information on specific tide level is available.  Hobson (1967) suggests that distribution is instead based on sediment composition. Associates: In a commensal relationship, Pinnixa schmitti is known to cohabit the burrow of A. pacifica (O’Clair and O’Clair 1998). Abundance: Often to 50/m2 (Kozloff 1974) and very dense in specialized habitats. Probably 2nd most abundant macroscopic animal in Coos Bay (Porch 1970). A. pacifica was much less abundant than in preceding years-- it was sparse (<1/m2) on Portside beach in April 2015 (Emlet pers com).  Life History Information Reproduction: Iteroparous.  Eggs and sperm discharged from nephridiopores, while both sexes are in their burrows.  Males release thin membranous spermatophores (0.5–0.2 mm in diameter) which fall into female burrows and are ruptured by female setae (Okuda 1936; Fernald et al. 1987).  Oocytes are pink to pale yellow and 160-190 µm in diameter with conspicuous envelope (Fernald et al. 1987).  Fertilization occurs in female's burrow.  Broods are found within burrows January-early April (Washington) and develop within gelatinous masses (Fernald et al. 1987).    Larva: Planktonic larvae are non-feeding and hatch from gelatinous masses within adult tubes as 2 setiger stages (Fernald et al. 1987).  Only the larvae of two local Arenicolidae species are known (Arenicola marina and Abarenicola claparedii, Crumrine 2001).  Juvenile: Longevity: Growth Rate: Relative growth rate of 0–6% per day, depending on age and food quality (Linton and Taghon 2000). Food: Primarily detritus, picked up by mucus of proboscis (Fig. 1) and digested out of sand and mud, which is then defecated.  Depending on sediment type, A. pacificia may utilize a variety of feeding modes (deposit, suspension, direct dissolved organic matter uptake) (Hylleberg 1975).  Feeding activity by Abarenicola pacifica is instrumental in bioturbation and generation of clay laminae (Swinbanks 1981).  Predators: Arenicolids have many predators including most estuarine creatures: man (for fish bait), birds, fish.  A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12654 and full 3rd edition: http://hdl.handle.net/1794/18839  Email corrections to oimbref@uoregon.edu Behavior: Most research into the behavior of A. pacific is focused on bioturbation and particle selection (Hylleberg 1975).  Bibliography 1. BLAKE, J. A., and E. R. RUFF. 2007. Polychaeta, p. 309-410. In: Light and Smith manual: intertidal invertebrates from central California to Oregon. J. Carlton (ed.). University of California Press, Berkeley, CA. 2. CRUMRINE, L. 2001. Polychaeta, p. 39-77. In: Identification guide to larval marine invertebrates of the Pacific Northwest. A. Shanks (ed.). Oregon State University Press, Corvallis, OR. 3. FAUCHALD, K. 1977. The polychaete worms: definitions and keys to the orders, families, and genera. Natural History Museum of Los Angeles County Science Series. 28:1-190. 4. FERNALD, R. L., C. O. HERMANS, T. C. LACALLI, W. H. WILSON, JR, and S. A. WOODIN. 1987. Phylum Annelida, Class Polychaeta, p. 138-195. In: Reproduction and development of marine invertebrates of the northern Pacific coast. M. F. Strathmann (ed.). University of Washington Press, Seattle, WA. 5. HEALY, E. A., and G. P. WELLS. 1959. Three new lugworms (Arenicolidae, Polychaeta) from the north Pacific area. Proceedings of the Zoological Society of London. 133:315-335. 6. HOBSON, K. D. 1966. Ecological obervations on Abarenicola species (Polychaeta) of the north Pacific, M. S. University of Washinton, Seattle, WA. 7. HOBSON, K. D. 1967. The feeding and ecology of two North Pacific Abarenicola species. (Arenicolidae, Polychaeta). Biological Bulletin. 133:323-354. 8. HYMEL, S. N., and C. J. PLANTE. 2000. Feeding and bacteriolytic responses of the deposit-feeder Abarenicola pacifica (Polychaeta : Arenicolidae) to changes in temperature and sediment food concentration. Marine Biology. 136:1019-1027. 9. HYLLEBERG, J. 1975. Selective feeding by Abarenicola pacifica with notes on Abarenicola and a concept of gardening in lugworms. Ophelia. 14:113-137. 10. KOZLOFF, E. 1993. Seashore life of the northern Pacific coast: an illustrated guide to northern California, Oregon, Washington, and British Columbia. University of Washington Press, Seattle, WA. 11. KOZLOFF, E. N. 1974. Keys to the marine invertebrates of Puget Sound, the San Juan Archipelago, and adjacent regions. University of Washington Press, Seattle. 12. LINTON, D. L., and G. L. TAGHON. 2000. Feeding, growth, and fecundity of Abarenicola pacifica in relation to sediment organic concentration. Journal of Experimental Marine Biology and Ecology. 254:85-107. 13. O'CLAIR, R. M., and C. E. O'CLAIR. 1998. Southeast Alaska's rocky shores: animals. Plant Press, Auke Bay, AK. 14. OGLESBY, L. C. 1973. Salt and water balance in lugworms (Polychaeta: Areniocolidae), with particular reference to Abarenicola pacifica in Coos Bay, Oregon. Biological Bulletin. 145:180-199. 15. OKUDA, S. 1938. Notes on the spawning habits of Abarenicola claparedii Levinsen. Annotationes Zoologicae Japonenses. 17:577. 16. PORCH, L. L. 1970. Polychaetes of Coos Bay. In: OIMB Unpublished Student Report, Summer 1970. 17. RICKETTS, E. F., and J. CALVIN. 1971. Between Pacific tides. Stanford University Press, Stanford, California. 18. RUPPERT, E. E., R. S. FOX, and R. D. BARNES. 2004. Invertebrate zoology: a functional evolutionary approach. Thomson Brooks/Cole, Belmont, CA. 19. SWINBANKS, D. D. 1981. Sediment reworking and the biogenic formation of clay laminae by Abarenicola  Hiebert, T.C. 2014. Abarenicola pacifica. 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. pacifica.  Journal of Sedimentary Petrology. 51(4): 1137-1145. 

Abarenicola pacifica

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