Balanus Nubilus Class: Multicrustacea, Hexanauplia, Thecostraca, Cirripedia

Home , Balanus nubilus, Conopea, Hexanauplia, Multicrustacea, Sessilia

Phylum: Arthropoda, Crustacea

Balanus nubilus Class: Multicrustacea, Hexanauplia, Thecostraca, Cirripedia

Order: Thoracica, Sessilia, Balanomorpha The giant barnacle Family: Balanoidea, Balanidae, Balaninae

Description Plates: Calcareous, nearly coni- Size: Largest barnacle on the Pacific coast, cal and columnar. Six in family Balanidae. and probably in the world (Ricketts and Cal- Each plate is composed of parietes (exposed vin 1971), with individuals up to 100 mm in triangular part), alae (the plate overlapping diameter, and nearly as tall (Cornwall 1951). plate edges) and radii (the plate edge marked The illustrated specimen (from Coos Bay) is off from the parietes by a definite change in 90 mm in diameter. direction of growth lines) (Newman 2007). Color: Shell dirty white with interior of scuta The plates themselves include the carina, the and terga (see Plate 18, Kozloff 1993) buff carinolateral plates and the compound ros- and tergal beak usually purple tipped trum (see Fig. 3, Balanus glandula, this (Cornwall 1951). guide). Internal surfaces with fine horizontal General Morphology: Members of the Cirri- ribbing above and smooth near base, particu- pedia, or barnacles, can be recognized by larly in older specimens (Pilsbry 1916). Radii their feathery thoracic limbs (called cirri) that rather narrow (Darwin 1854). are used for feeding. There are six pairs of Opercular Valves: Thick and yellow- cirri in B. nubilus. Sessile barnacles are sur- ish, buff on interior but never white. Tergal rounded by a shell that is composed of a flat beaks project above orifice edge (Cornwall basis attached to the substratum, a wall 1977). Tergal and scutal adductor and de- formed by several articulated plates (six in pressor muscles are very thick in B. nubilus (2 Balanus species) and movable opercular mm and 1.4 mm, respectively, Hoyle and valves including terga and scuta (Newman Smyth 1963). 2007) (Figs. 1, 3, 4). Scuta: External surface with Shell: Exterior can be rugged and worn with prominent growth lines, a deep canal from well-developed ribs that become eroded with apex and downward in old eroded specimens age (Figs. 1, 2) (Cornwall 1977). (Fig. 4b). Internally with low articular ridge Shape: Steeply conical and, like oth- that has a very narrow articular furrow. The er barnacles, they can become cylindrical prominent adductor ridge is large and with a when crowded. Young specimens can also shallow adductor pit. be cylindrical (Henry 1940). Terga: Beak triangular and of- Basis: Calcareous and flat, attached ten purple (Fig 4a), especially in older speci- to hard substrate, rendering B. nubilus a mens (Cornwall 1951). External growth sessile, or attached barnacle ridges narrow and regular, with narrow, shal- (Balanomorpha). Barnacle base is thick, po- low longitudinal furrow. Internally, numerous rous at edges and thin at center. depressor muscle crests. Tergal spur is wide Wall: at base and tapers to a narrow truncate end Longitudinal Tubes: A single (Fig. 4a). Moderate articular ridge is with row of tubes is uniform and within shell walls shallow broad articular furrow (Fig. 4a). (Ricketts and Calvin 1971). Aperture: Large, flared and with a jag-

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Hiebert, T.C. 2015. Balanus nubilus. 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.

ged edge (Cornwall 1977). scutum, and by its unique and unusual Cirri: Six pairs of conspicuous feathery membraneous base. Balanus nubilus, feeding appendages. would be most likely to be confused with S. cariosus at subtidal levels. Both species, as Possible Misidentifications juveniles, have strong ribs. S. cariosus has There are three groups (i.e. super- the characteristic starry border, however, orders) of cirripeds including the Rhizo- that B. nubilus lacks. Both species have a cephala, (parasites among crustaceans), tergal plate with a long spur (Figs. 3b, 4a), the Acrothoracica (shell-less burrowing but that of S. cariosus is pointed, while it is forms) and the Thoracica. The Thoracica truncate in B. nubilus. The cirri of S. ca- contains 1,000 species worldwide includ- riosus are conspicuous and almost black. ing the monophyletic taxa, Lepadomorpha, Balanidae encompasses the genera the stalked barnacles, and the Balanomor- Megabalanus, Paraconcavus, and Menesin- pha, or sessile barnacles (Perez-Losada et iella (each with one local species), Amphi- al. 2008; Chan et al. 2014). Among the balanus (three local species) and Balanus sessile forms, there are four families repre- (four local species). Balanus nubilus, is sented locally. The family Chthamaloidea easily distinguished from other species by includes members of the genus its large size and a shell aperture that is rel- Chthamalus, which has alae on its rostral atively large and flaring (Newman 2007). plates, not radii. Chthamalus dalli is found Balanus trigonus is a lower intertidal species both with and at higher tide levels than is with a southern distribution (to Monterey B. glandula, and individuals are usually Bay, California). Balanus crenatus is gener- brown. The family Tetraclitoidea has one ally found in the intertidal at a lower level species locally (Tetraclita rubescens) and than the ubiquitous and morphologically is characterized by a wall that is composed similar B. glandula. Balanus glandula has of four plates (rather than six in the Balani- no longitudinal wall tubes (except when dae). young) and it differs in the structure of terga The remaining two families include and scuta: the tergum is very wide and has the Balanidae and Archaeobalanidae. The longer spurs and the scutum has no adduc- Archaeobalanidae includes the genera Ar- tor ridge. Balanus crenatus, on the other matobalanus, Conopea, Hesperibalanus hand, has a shell wall with a single row of and Semibalanus (each with one local spe- uniformly spaced tubes (Newman 2007). cies). The latter genus includes a common local intertidal species S. cariosus (and for- Ecological Information mer member of the genus Balanus). An Range: Type region is Monterey Bay, Califor- isolated S. cariosus, is with splinter-like nia (Cornwall 1951). Known distribution spines, nearly black cirri and is not likely to includes the west coast of North America from be confused with another barnacle. It has the southern boundary of Alaska to the mid a thatched appearance, being irregularly Baja California coast. ribbed: its walls have uneven, longitudinal Local Distribution: Common in Coos Bay tubes (Pilsbry 1916). However, where it is and at several locations along the South crowded or eroded, these spines may be Slough as well as south in Port Orford (Pilsbry worn off or not developed, and the barna- 1916). cle would have to be distinguished from Habitat: Suitable substrates include pilings in other common barnacles by its tergum and bays with strong tidal action (Cornwall 1951),

rocks, shell hash and kelp holdfasts embryos are retained in ovisacs within the (Cornwall 1977). Largest specimens are mantle cavity and are discharged as nauplii observed on fairly exposed wharf pilings after four months (Høeg et al. 1987; Arnsberg where individuals can grow on top of each 2001). For detailed reproductive anatomy see other to make accretions one foot high Høeg et al. (1987). (Ricketts and Calvin 1971). Larva: Cirriped broods hatch as nauplius lar- Salinity: Collected at salinities of 30 and no vae and undergo 4–6 naupliar stages, each known collections from brackish water. larger and more setose than the last (Høeg et Balanus nubilus individuals can regulate pH al. 1987; Arnsberg 2001; Chan et al. 2014). within their muscle fibers, but require exter- The generalized cirriped nauplius has a trian- nal sodium ions to do so (Boron et al. 1981). gular or shield-shaped carapace with fron- Considerable research is focused on the tolateral horns and a conspicuous naupliar physiology and neuroscience of B. nubilus eye (Fig. 1, Arnsberg 2001; Figs. 22.1–22.2, (e.g. Hoyle and Smyth 1963; Morris and Chan et al. 2014). In B. nubilus, the nauplius Lecar 1981; Stockbridge and Ross 1984; is characterized by straight frontolateral horns Ross et al. 1986; Callaway et al. 1989). and a goblet-shaped carapace, in naupliar Temperature: From temperate waters. stages 2–6 (Fig. 11, Arnsberg 2001). The Tidal Level: From low to shallow waters (3– carapace shape in B. nubilus is recognizable 6 meters) and occasionally to 55 meters and makes them easy to identify from other (Cornwall 1977). Balanus species (Arnsberg 2001). The final Associates: Often encrusted with other bar- larval stage in cirripeds is called a cyprid, a nacles, sea stars and anemones on over- non-feeding stage that attaches to a substrate hanging rocks (British Columbia, Canada, by its antennae, secretes a cement and builds Cornwall 1951). Boring sponges can erode the adult calcareous shell (Ricketts and Calvin shells (Cornwall 1977). Individuals also 1971). Cyprids are oblong and composed of occur on boat bottoms with mussels and a bivalve shell, six thoracic appendages, a congeners (MacGinitie and MacGinitie 1949) pair of compound eyes and a conspicuous and is often covered with brown furry mats lipid reserve anteriorly (Fig. 3, Arnsberg 2001; of the entoproct, Barentsia (Pilsbry 1916). Figs. 22.2–22.3, Chan et al. 2014). Cyprids Abundance: The second most common prefer rough surface for settlement (Yonge barnacle of the low intertidal zone (most 1963). Cyprid larvae in B. nubilus are charac- abundant is Semibalanus cariosus, Pilsbry terized by a broadly rounded anterior and nar- 1916). More common in Puget Sound, row posterior and a large size (800–1000 µm) Washington and north (Ricketts and Calvin (Fig. 12, Arnsberg 2001). The cyprids of B. 1971) where individuals characteristically crenatus are most similar to those of B. nu- grow in large clumps on rocky bottoms bilus, but they have a narrower anterior, a dis- (Henry 1940). tinct evenly curved posterodorsal margin, and black pigment carapace spots (Arnsberg Life-History Information 2001). Reproduction: Cirripeds usually brood their Juvenile: Often with cylindrical morphology. eggs and while individuals are hermaphro- Longevity: ditic and, although self-fertilization is pos- Growth Rate: Cirriped body growth occurs in sible, cross-fertilization is the rule for grega- conjunction with molting (Kuris et al. 2007). rious types like B. nubilus (MacGinitie and Shell growth depends on barnacle density MacGinitie 1949; Yonge 1963). Eggs and (e.g. crowded individuals tend to be tall and

columnar). 5. COCHRAN, T. 1968. Effects of predation Food: Filter and suspension feeder. upon the intertidal cirriped population. Vol. Predators: Balanus species are usually Summer, Book 1. OIMB (ed.), Charleston, preyed upon by sea stars (e.g. Pisaster spe- OR. cies) and by the nemertean Emplectonema 6. CORNWALL, I. E. 1951. Arthropoda: Cirri- gracile (Cochran 1968). It has been sug- pedia. In: Canadian Pacific Fauna. Univer- gested that predation by Thais, a genus of sity of Toronto Press for the Fisheries Re- drilling gastropods has influenced plate mor- search Board of Canada, Toronto. phology over evolutionary time in balano- 7. —. 1977. The Barnacles of British Colum- morph barnacles (Palmer 1982). bia. British Colonial Provincial Museum, Behavior: Individuals tend to grow in Victoria. accretions into deep clusters that often 8. DARWIN, C. 1854. A Monograph of the create a heavy clump (i.e. hummock) which subclass Cirripedia (Part II Balandiae). falls off substrate and sinks to bottom where Royal Society, London. animals cannot live. Balanus nubilus 9. HENRY, D. P. 1940. The Cirripedia of Pu- individuals can detect changes in light with get Sound with a key to the species. Uni- photoreceptors in three simple eyes. A versity of Washington Publications in single medial eye contains four Oceanography. 4:1-48. photoreceptors, while the two lateral eyes 10. HOYLE, G., and T. SMYTH, JR. 1963. Gi- contain three each (Stockbridge and Ross ant muscle fibers in a barnacle, Balanus 1984; Callaway et al. 1989). nubilus (Darwin). Science. 139:49-50. 11. HØEG, J. T., P. L. LIIG, R. R. STRATH- Bibliography MANN, and D. S. WETHEY. 1987. Phylum 1. ARNSBERG, A. J. 2001. Arthropoda, Cir- Crustacea, class Maxillopoda, subclass ripedia: the barnacles, p. 155-175. In: An Cirripedia, p. 370-392. In: Reproduction identification guide to the larval marine and development of marine invertebrates invertebrates of the Pacific Northwest. A. of the northern Pacific coast. M. F. Strath- L. Shanks (ed.). Oregon State University mann (ed.). University of Washington Press. Press, Seattle. 2. BORON, W. F. 1981. pH regulation in 12. KOZLOFF, E. N. 1993. Seashore life of barnacle muscle fibers: dependence on the northern Pacific coast: an illustrated extracellular sodium and bicarbonate. guide to northern California, Oregon, American Journal of Physiology. 240:C80 Washington, and British Columbia. Univer- -C89. sity of Washington Press, Seattle. 3. CALLAWAY, J. C., A. E. STUART, and J. 13. KURIS, A. M., P. S. SADEGHIAN, J. T. S. EDWARDS. 1989. Immunocytochemi- CARLTON, and E. CAMPOS. 2007. De- cal evidence for the presence of hista- capoda, p. 632-656. In: The Light and mine and GABA in photoreceptors of the Smith manual: intertidal invertebrates from barnacle (Balanus nubilus). Visual Neu- central California to Oregon. J. T. Carlton roscience. 3:289-299. (ed.). University of California Press, Berke- 4. CHAN, B. K. K., J. T. HØEG, and R. KA- ley, CA. DO. 2014. Thoracica, p. 116-124. In: At- 14. MACGINITIE, G. E., and N. MACGINITIE. las of crustacean larvae. J. W. Margtin, J. 1949. Natural history of marine animals. Olesen, and J. T. Høeg (eds.). Johns McGraw-Hill Book Co., New York. Hopkins University Press, Baltimore. 15. MORRIS, C., and H. LECAR. 1981. Volt-

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