Balanus Crenatus Phylum: Arthropoda, Crustacea Class: Cirripedia Order: Thoracica, Sessilia the Crenulated Barnacle Family: Balanidae

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Balanus crenatus Phylum: Arthropoda, Crustacea Class: Cirripedia Order: Thoracica, Sessilia The crenulated barnacle Family: Balanidae

Description Longitudinal Tubes: Present within Size: Small, rarely more than 13 mm in walls and visible if wall is broken (Fig. 4). diameter (Cornwall 1977). Average size is Tubes occur in a single row and are uniformly approximately 14 mm (Cornwall 1951) with spaced (Newman 2007). Some specimens the largest individual recorded with diameter can have cross-septa in the upper part of the of 28 mm (Henry 1940). wall. Color: White with yellowish epidermis Plates: Calcareous, nearly conical (Cornwall 1977) and exterior without colored and columnar. Six in family Balanidae. Each markings (Newman 2007). Feeding cirri and plate is composed of parietes (exposed penis are cream in color, with the rest of the triangular part), alae (the overlapping plate body being rust-colored. edges) and radii (the plate edge marked off General Morphology: Members of the from the parietes by a definite change in Cirripedia, or barnacles, can be recognized by direction of growth lines) (Newman 2007). their feathery thoracic limbs (called cirri) that The plates themselves include the rostrum, are used for feeding. There are six pairs of opposite it the carina and between the carina cirri in B. crenatus (Fig. 2). Sessile barnacles and rostrum are the four side plates, the are surrounded by a shell that is composed carinolateral and rostrolateral plates (see Fig. of a flat basis attached to the substratum, a 3, Balanus glandula, this guide). wall formed by several articulated plates (six Opercular Valves: One pair of scuta in Balanus species) and movable opercular opposite the rostrum and a pair of terga at valves including a terga and scuta (Newman carinal end of orifice (Fig. 1). Growth lines in 2007) (Figs. 1, 3, 5). both valves are not highly prominent. Shell: Shell can be rough or smooth and Variation in valve morphology (e.g. smooth varies greatly (Henry 1940), but is usually and thin versus rough and cylindrical) may be more smooth than the similar species B. due to habitat (Barnes and Healy 1969). glandula (Kozloff 1993). Alaskan species are Scuta: Lacks adductor ridge, generally ridged while Oregon specimens are is small with flattened beaks (not peaked), smoother (see Fig. 51, Kozloff 1993). and a shallow adductor muscle pit with a well- Shape: Usually broader than tall developed articular ridge (Fig. 5b). (Kozloff 1993). Conical, but can be cylindrical Terga: A short spur that is if crowded in hummocks, where shape and wider than long and occupies at least ½ of growth depends on an individual’s position basal margin (Newman 2007). A long, high, within the hummock (e.g. Plate 3, Barnes and articular ridge is present with a deep furrow Powell 1950). beside it (Fig. 5a) (Henry 1942). Basis: Calcareous and flat, attached Aperture: A large, rhomboidal orifice, to hard substrate, rendering B. crenatus a from which the cirri emerge when feeding, is sessile, or attached barnacle (Balanomorpha) controlled by movement of the terga and Wall: Formed by six unequal plates. scuta in conjunction with adductor and The carinal edge of the wall projects forward depressor muscles (Fig. 1). The internal edge over the base (Fig. 3) with radii narrow and projects inward in some specimens (Pilsbry internal surface of wall ribbed horizontally 1916). When closed, plates produce a less (Fig. 4). Lower inner wall can be ribbed, sinuous line than is present in B. glandula smooth, rough, or plicated (Henry 1940). (Kozloff 1993).

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12693 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] Cirri: Six pairs of feathery cirri are outline, which would distinguish it from young conspicuous (Fig. 2) and cream in color. B. crenatus or B. glandula. Generally, these latter two species are found higher in the Possible Misidentifications intertidal than S. cariosus, which occurs There are three groups (i.e. superorders) of mostly subtidally. cirripeds including the Rhizocephala, Balanidae encompasses the genera (parasites among crustaceans), the Megabalanus, Paraconcavus, and Acrothoracica (shell-less burrowing forms) Menesiniella (each with one local species), and the Thoracica. The Thoracica contains Amphibalanus (three local species) and 1,000 species worldwide including the Balanus (four local species). Balanus monophyletic taxa, Lepadomorpha, the crenatus is generally found in the intertidal stalked barnacles, and the Balanomorpha, at a lower level than the ubiquitous and or sessile barnacles (Perez-Losada et al. morphologically similar B. glandula. 2008; Chan et al. 2014). Among the sessile Balanus glandula has no longitudinal wall forms, there are four families represented tubes (except when young) and it differs in locally. The family Chthamaloidea includes the structure of terga and scuta: the terga members of the genus Chthamalus, which are very wide and have longer spurs and has alae on its rostral plates, not radii. the scuta have no adductor ridge (compare Chthamalus dalli is found both with and at Fig. 5 with B. glandula Figs. 4, 5, this higher tide levels than B. glandula, and guide). Balanus crenatus, on the other individuals are usually brown. The family hand, has a shell wall with a single row of Tetraclitoidea has one species locally uniformly spaced tubes (Newman 2007). (Tetraclita rubescens) and is characterized Balanus crenatus is a difficult barnacle to by a wall that is composed of four plates identify: "Not only does every external (rather than six in the Balanidae). character vary greatly in this species, but The remaining two families include the the internal parts very often vary to a Balanidae and Archaeobalanidae. The surprising degree, and to add to the Archaeobalanidae includes the genera difficulty, groups of specimens do not rarely Armatobalanus, Conopea, Hesperibalanus vary in the same manner” (Charles Darwin and Semibalanus (each with one local in Cornwall 1951). Balanus nubilus, the species). The latter genus includes a giant acorn barnacle, is easily distinguished common local intertidal species S. cariosus from B. glandula by its large size, reaching (and former member of the genus Balanus). 100 mm in diameter, and a shell aperture An isolated S. cariosus, is with splinter-like that is relatively large and flaring (Newman spines, nearly black cirri and is not likely to be 2007). Balanus trigonus is a lower intertidal confused with another barnacle. It has a species with a southern distribution (to thatched appearance, being irregularly ribbed Monterey Bay, California). and its walls have uneven, longitudinal tubes (Pilsbry 1916). However, where it is crowded Ecological Information or eroded, these spines may be worn off or Range: Type locality is the English coast. not developed, and the barnacle would have Known range includes the North Atlantic and to be distinguished from other common Pacific from the Bering Sea to Santa Barbara, barnacles by its terga and scuta, and by its California. Balanus crenatus is a common unique and unusual membraneous base. species in the fossil record. Semibalanus cariosus have terga with a long Local Distribution: Protected waters of most pointed spur, quite different from either B. northwest bays including many sites in and crenatus or B. glandula. Semibalanus around Coos Bay. cariosus commonly co-occurs with B. Habitat: Suitable substrates include pilings, crenatus, B. glandula, as well as with worm tubes, mollusk and crab shells, boat Chthamalus dalli. Juvenile S. cariosus will bottoms, wood and other hard substrates show a typical heavy ribbing and starry basis

Hiebert, T.C. 2015. Balanus crenatus. 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. (Kozloff 1993). Individuals also often occur 1982. Larvae molt to the second naupliar amongst eelgrass and debris. stage shortly after hatching (Branscomb and Salinity: Collected at salinities of 30 and is Vedder 1982). The generalized cirriped usually found in full-strength seawater, nauplius has a triangular or shield-shaped although individuals were found on carapace with frontolateral horns and a Vancouver Island in brackish water (Henry conspicuous naupliar eye (Fig. 1, Arnsberg 1942). 2001; Figs. 22.1–22.2, Chan et al. 2014). In Temperature: Found in cold and temperate B. crenatus, the nauplius carapace is slightly waters. curved anteriorly, between the frontolateral Tidal Level: Low intertidal down to 165 horns (Fig. 9B, Arnsberg 2001). The last meters, but is usually from shallower waters three naupliar stages have similar along Pacific coasts (Pilsbry 1916). morphology to Semibalanus cariosus, but are Associates: Co-occurs with other barnacle smaller. To differentiate between species species including B. glandula, S. cariosus with superficially similar nauplii (e.g. S. (British Columbia, Canada, Cornwall 1977), cariosus, B. glandula, B. crenatus) see Fig. 9 and Chthamalus dalli (Puget Sound, (Arnsberg 2001). The final larval stage in Washington, Henry 1940). In mud and cirripeds is called a cyprid, a non-feeding eelgrass, associates include amphipods, stage that attaches to a substrate by its littorine snails, isopods, B. glandula, and the antennae, secretes a cement (for biochemical mussel, Mytilus edulis (South Slough). composition of cement, see Walker 1972; Readily settles on recently dead Ensis Naldrett and Kaplan 1997) and builds the americanus shells (internal and external shell adult calcareous shell (Ricketts and Calvin portions) (Donovan et al. 2013). 1971). Cyprids are oblong and composed of Abundance: Quite common (Cornwall 1951) a bivalve shell, six thoracic appendages, a among the sessile barnacles and may be the pair of compound eyes and a conspicuous most common of all invertebrates on rocky lipid reserve anteriorly (Fig. 3, Arnsberg 2001; shores (Yonge 1963). Figs. 22.2–22.3, Chan et al. 2014). Cyprids prefer rough surfaces for settlement (Yonge Life-History Information 1963), and although algal abundance may Reproduction: Cirripeds usually brood their positively influence larval settlement in other eggs and B. crenatus has two broods per barnacle species (Strathmann et al. 1981), B. year, even at the southern edge of range crenatus individuals settle on clean surfaces (Barnes and Powell 1953). Individuals are (Hudon et al. 1983). Cyprid larvae in B. hermaphroditic and self-fertilization is crenatus have a rounded posterior and a possible, but not common (Pilsbry 1916; ventral margin that is straight. The carapace MacGinitie and MacGinitie 1949; Yonge is shiny and smooth, with one pair of distinct 1963). Eggs and embryos are retained in black pigment spots just posterior to the eyes ovisacs within the mantle cavity and are and is larger than the congener B. glandula at discharged as nauplii after four months (Høeg 700–960 µm in length (Fig. 10, Arnsberg et al. 1987; Arnsberg 2001). Light does not 2001). The cyprids of B. crenatus are most affect growth, fertilization or embryonic similar to those of B. nubilus, but they have a development (Newman and Abbott 1980) and narrower anterior, a distinct evenly curved reproduction in B. crenatus can occur posterodorsal margin, and black pigment continuously, but is limited by available food carapace spots (Arnsberg 2001). Larval and temperature (17˚C) (Crisp and Patel duration is approximately 2–3 weeks in the 1969). For detailed reproductive anatomy see plankton (Newman and Abbott 1980) and Høeg et al. (1987). metamorphosis occurs between 14 and 62 Larva: Cirriped broods hatch as nauplius hours after initial attachment to substrate larvae and undergo 4–6 naupliar stages, each (Meadow 1969). Settlement is dependent on larger and more setose than the last (Høeg et biological, chemical and physical cues as well al. 1987; Arnsberg 2001; Chan et al. 2014). as the presence of conspecifics with over For naupliar setal formulae and antenna 30% of settlement occurring on adult shells morphology, see Branscomb and Vedder (Miron et al. 1996).

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12693 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] Juvenile: BRANSCOMB, E. S., and K. VEDDER. 1982. Longevity: A description of the naupliar stages of Growth Rate: Shell growth in B. crenatus is the barnacles Balanus glandula highly dependent on whether individuals are (Darwin), Balanus cariosus (Pallas), crowded in dense hummocks or solitary and Balanus crenatus (Bruguiere) (Barnes and Powell 1950). Individuals (Cirripedia, Thoracica). Crustaceana. measured on settlement plates reached near 42:83-95. their maximum size (rostro-carinal length of CHAN, B. K. K., J. T. HØEG, and R. KADO. 20–25 mm) within the first growing season 2014. Thoracica, p. 116-124. In: Atlas (Millport, United Kingdom, Barnes and Powell of crustacean larvae. J. W. Margtin, J. 1953). In the first three months after Olesen, and J. T. Høeg (eds.). Johns metamorphosis, growth rate ranges between Hopkins University Press, Baltimore. 0.1 and 3.9 mm per month (Meadow 1969). CORNWALL, I. E. 1951. Arthropoda: Body growth occurs in conjunction with Cirripedia. In: Canadian Pacific Fauna. molting, as is seen in other crustaceans (Kuris University of Toronto Press for the et al. 2007). Fisheries Research Board of Canada, Food: Toronto. Predators: —. 1977. The Barnacles of British Columbia. Behavior: British Colonial Provincial Museum, Victoria. Bibliography CRISP, D. J., and B. PATEL. 1969. ARNSBERG, A. J. 2001. Arthropoda, Environmental control of the breeding Cirripedia: The Barnacles. In: An of three boreo Arctic cirripedes identification guide to the larval marine Balanus balanoides, Balanus balanus, invertebrates of the Pacific Northwest. Balanus crenatus. Marine Biology A. L. Shanks (ed.). Oregon State (Berlin). 2:283-295. University Press. DONOVAN, S. K., L. COTTON, C. VAN DEN BARNES, H., and M. J. R. HEALY. 1969. ENDE, G. SCOGNAMIGLIO, and M. Biometrical studies on some common ZITTERSTEIJN. 2013. Taphonomic cirripedes. II. Discriminate analysis of significance of a dense infestation of measurements on the scuta and terga Ensis americanus (Binney) by Balanus of Balanus balanus, Balanus crenatus, crenatus (Brugiere), North Sea. Balanus improvisus, Balanus glandula Palaios. 28:837-838. and Balanus amphitrite stutrsburi, HENRY, D. P. 1940. The Cirripedia of Puget Balanus pallidus stutsburi. Journal of Sound with a key to the species. Experimental Marine Biology and University of Washington Publications Ecology. 4:51-70. in Oceanography. 4:1-48. BARNES, H., and H. T. POWELL. 1950. The —. 1942. Studies on the sessile Cirripedia of development, general morphology and the Pacific coast of North America. subsequent elimination of barnacle University of Washington Publications populations. Balanus crenatus and B. in Oceanography. 4:95-134. balanoides, after a heavy initial HUDON, C., E. BOURGET, and P. settlement. Journal of Animal Ecology. LEGENDRE. 1983. An integrated 19:175-179. study of the factors influencing the —. 1953. The growth of Balanus balanoides choice of the settling site of Balanus (L.) and B. crenatus (Brug.) under crenatus cyprid larvae. Canadian varying conditions of submersion. Journal of Fisheries and Aquatic Journal of the Marine Biological Sciences. 40:1186-1194. Association of the United Kingdom. HØEG, J. T., P. L. LIIG, R. R. 32:107-127. STRATHMANN, and D. S. WETHEY. 1987. Phylum Crustacea, class