Semibalanus Cariosus Class: Thecostraca, Cirripedia Order: Thoracica, Sessilia a Thatched Barnacle Family: Archaeobalanidae

Phylum: Arthropoda, Crustacea Semibalanus cariosus Class: Thecostraca, Cirripedia Order: Thoracica, Sessilia A thatched barnacle Family: Archaeobalanidae

Taxonomy: Semibalanus cariosus originally membraneous, in contrast to most barnacles belonged to the genus Balanus. Members of which have calcareous bases (Cornwall 1951) the genus Semibalanus, which was described and base forms unique starry pattern (Fig. 1), (initially as a subgenus) by Pilsbry in 1916, especially in juveniles (Fig. 3) (Ricketts and differ from Balanus species with the presence Calvin 1971). of membranous bases (Newman and Ross Wall: Formed by plates and is thick 1976). Thus, a common known synonym for when isolated, but thinner when crowded. S. cariosus is B. cariosus. The internal surface is usually with faint ribs or wrinkled texture (Cornwall 1951) (Fig. 4). Description Longitudinal Tubes: Within Size: Individuals typically up to 75 mm in walls, tubes are irregular (Fig. 4) and with diameter (Henry 1940) and 80 mm in height. cross-septa. They are sometimes filled with Size is highly variable, especially in cylindrical powder (Pilsbry 1916). specimens on vertical surfaces, but is not Plates: Six, unequal and limited by mechanical factors of a wave swept calcareous plates bear narrow longitudinal environment (Denny et al. 1985). For spines, giving specimens a unique thatched example, individuals from Puget Sound, appearance (Fig. 1). Each plate is composed Washington can grow to 100 mm high while of parietes (exposed triangular part), alae only 15 mm in diameter (Pilsbry 1916). (overlapping plate edges) and radii (the plate Color: Shell dirty white, gray with round or edge marked off from the parietes by a uncrowded specimens chalky white. Tergum definite change in direction of growth lines) beak can be purple (Pilsbry 1916) and cirri (Newman 2007). The plates themselves are brown to almost black. include the rostrum, opposite it the carina and General Morphology: Members of the between the carina and rostrum are the four Cirripedia, or barnacles, can be recognized by side plates, the carinolateral and rostrolateral their feathery thoracic limbs (called cirri) that plates (see Fig. 3, Balanus glandula, this are used for feeding. There are six pairs of guide). When crowded, cylindrical specimens cirri in S. cariosus. Sessile barnacles are often lack spines (Cornwall 1977). Rostrum surrounded by a shell that is composed of a overlaps adjacent lateral plates (see Plate flat basis attached to the substratum, a wall 213, Newman 2007). Radii narrow (Cornwall formed by several articulated plates and 1951). movable opercular valves including terga Opercular Valves: Thin (Henry 1942) and scuta (Newman 2007). valves consist of two pairs of movable plates Shell: inside the wall, which close the aperture: the Shape: Conical when isolated (Fig. tergum and the scutum (Figs. 5, 6). 2), but can be cylindrical if crowded (see Fig. Scuta: Exterior with low 108, Kozloff 1993). growth ridges, the lower ridges are fringed Basis: Calcareous and flat, attached with membrane and usually with a weak to hard substrate, rendering S. cariosus a longitudinal striation. Interior a small, well- sessile, or attached barnacle reflexed articular ridge is present, which is (Balanomorpha). Basis in S. cariosus is continued as a sharp, high, curved adductor

Hiebert, T.C. 2015. Semibalanus cariosus. 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/1794/12735 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected]

ridge (in some specimens, the adductor ridge Balanidae encompasses the genera is very weak). A depressor muscle pit is deep Megabalanus, Paraconcavus, and and rather large, often divided by one or two Menesiniella (each with one local species), ridges. The occludent margin is with 3–5 Amphibalanus (three local species) and oblique coarse teeth (Henry 1940) (Figs. 5a, Balanus (four local species). The 6a). Archaeobalanidae includes the genera Terga: Very narrow and Armatobalanus, Conopea, Hesperibalanus beaked, with narrow furrow, and long and and Semibalanus (each with one local acute articular ridge. Very narrow and long species). An isolated S. cariosus, is with spur (Pilsbry 1916) that continue as a raised splinter-like spines, nearly black cirri and is ridge on the inside with strongly developed not likely to be confused with another depressor muscle crests (Figs. 5b. 6b). barnacle. It has a thatched appearance, Aperture: The shell opening, from being irregularly ribbed and its walls have which the cirri emerge when feeding, is uneven, longitudinal tubes (Pilsbry 1916). controlled by movement of the terga and However, where it is crowded or eroded, scuta in conjunction with adductor and these spines may be worn off or not depressor muscles. The aperture is small in developed, and the barnacle would have to conical specimens and large in cylindrical be distinguished from other common ones (Henry 1940), the aperture can be barnacles by its tergum and scutum, and by deeply toothed (Fig. 1). its unique and unusual membraneous base. Cirri: Six pairs of conspicuous feathery Semibalanus cariosus have terga with a feeding appendages. long pointed spur, quite different from either B. crenatus or B. glandula. Semibalanus Possible Misidentifications cariosus commonly co-occurs with B. There are three groups (i.e. crenatus, B. glandula, as well as with superorders) of cirripeds including the Chthamalus dalli. Juvenile S. cariosus will Rhizocephala (parasites among show a typical heavy ribbing and starry crustaceans), the Acrothoracica (shell-less outline, which would distinguish it from burrowing forms) and the Thoracica. The young B. crenatus or B. glandula. Thoracica contains 1,000 species worldwide Generally, these latter two species are including the monophyletic taxa, found higher in the intertidal than is S. Lepadomorpha, the stalked barnacles, and cariosus, which occurs mostly subtidally. the Balanomorpha, or sessile barnacles Balanus crenatus may be easily (Perez-Losada et al. 2008; Chan et al. 2014). confused with the ubiquitous B. glandula, but Among the sessile forms, there are four is generally found lower in the intertidal. families represented locally. The family Balanus glandula has no longitudinal wall Chthamaloidea includes members of the tubes (except when young) and it differs in genus Chthamalus, which has alae on its the structure of terga and scuta: the tergum rostral plates, not radii. The family is very wide and has longer spurs and the Tetraclitoidea has one species locally, scutum has no adductor ridge. Balanus Tetraclita rubescens, the southern thatched crenatus, on the other hand, has a shell wall barnacle, that is superficially similar to S. with a single row of uniformly spaced tubes cariosus. However, it is characterized by a (Newman 2007). Balanus trigonus is a lower wall that is composed of four plates (rather intertidal species with a southern distribution than six in the S. cariosus). Tetraclita (to Monterey Bay, California). Balanus rubescens occurs as far north as Monterey nubilus, the giant acorn barnacle, reaches Bay, California (Newman 2007). 100 mm in diameter, and has a shell aperture The remaining two families include that is relatively large and flaring (Newman the Balanidae and Archaeobalanidae. 2007). Balanus nubilus, would be most likely

to be confused with S. cariosus at subtidal correlation in abundance with substrate levels. Both species, as juveniles, have temperature in the mid-intertidal (Salish Sea, strong ribs: S. cariosus has the characteristic Washington, Harley 2011). Predation by sea starry border (Figs. 1, 3), however, that B. stars may determine lower vertical limit nubilus lacks. Both species have a tergal (Cochran et al. 1968). plate with a long spur, but that of S. cariosus Associates: Commonly grows below B. is pointed, while it is truncate in B. nubilus glandula, a barnacle that is often found (compare Figs. 5, 6 with Figs. 3b, 4a in B. growing on S. cariosus. Often grows on and nubilus, this guide). The cirri of S. cariosus amongst Mytilus californianus, with Littorina are also conspicuous and almost black. scutulata (outer coast) and with B. crenatus and the goose barnacle, Lepas pectinata Ecological Information pacifica and with masses of tube worms (e.g. Range: Type locality is the Kurile Islands. Eudistylia). Also co-occurs with the Known range includes the Bering Sea south barnacles, Chthamalus dalli and Pollicipes to Morro Bay, California (Newman and Abbott polymerus (outer coast) (Henry 1942). 1980) and Japan. (For range map see Abundance: Most common barnacle of low Newman and Abbott 1980, p 507.) estuarine zone, where the tall and crowded Local Distribution: Outer rocky coasts and variety can be as dense as 15,000 individuals protected sites in Oregon Bays. In Coos Bay, per square meter (Ricketts and Calvin 1971). also found on floating docks in the Charleston The highest density observed locally, at the Marina. OIMB Boat House, Coos Head was 270 Habitat: Hard surface needed for attachment individuals per 20 square centimeters (Holden (i.e. rock, shell, wood). Southern specimens 1968). prefer protected spots, including deep crevices and overhanging ledges, in the Life History Information presence of a strong current (Ricketts and Reproduction: Cirripeds usually brood their Calvin 1971). Puget Sound individuals live eggs and S. cariosus broods in the winter with exclusively in oceanic conditions. In Coos larvae hatching in the spring and summer Bay S. cariosus occurs on floating docks (Newman and Abbott 1980). In Vladivostok, (subtidally) just below the water line, versus Russia, spawning occurs once a year in B. glandula that clusters at the water line (e.g. November, larvae hatch in March and on floats) (Kozloff 1993). An ecosystem settlement occurs from April–May (Koch engineer, groups of S. cariosus (coupled with 1989). Individuals are hermaphroditic and Mytilus trossulus) create necessary self-fertilization is possible (e.g. in isolated microhabitats for other marine invertebrate individuals), but not common (MacGinitie and species (Harley 2011). MacGinitie 1949; Yonge 1963). Eggs and Salinity: Collected at salinities of 30 and embryos are retained in ovisacs within the prefers full-strength seawater. mantle cavity and are discharged as nauplii Temperature: Occurs in temperate waters, after four months (Høeg et al. 1987; Arnsberg with optimal feeding temperatures from 15 to 2001). For detailed reproductive anatomy 20 degrees C (Nishizaki and Carrington see Høeg et al. (1987). 2014). Larva: Cirriped broods hatch as nauplius Tidal Level: From high in splash zone (e.g. larvae and undergo 4–6 naupliar stages, each OIMB Boat House, Coos Bay) to more larger and more setose than the last (Høeg et protected areas farther up bay. Also occurs al. 1987; Arnsberg 2001; Chan et al. 2014). in the low intertidal zone and subtidally (e.g. For naupliar setal formulae and antenna floating docks in Charleston). Upper intertidal morphology, see Branscomb and Vedder limit may be determined by desiccation and 1982. Larvae molt to the second naupliar by substrate temperature as S. cariosus and stage shortly after hatching (Branscomb and B. glandula individuals showed a negative Vedder 1982). The generalized cirriped

nauplius has a triangular or shield-shaped Growth Rate: Cirriped body growth occurs in carapace with frontolateral horns and a conjunction with molting (Kuris et al. 2007). conspicuous naupliar eye (Fig. 1, Arnsberg Shell growth depends on barnacle density 2001; Figs. 22.1–22.2, Chan et al. 2014). In (e.g. crowded individuals tend to be tall and S. cariosus, the nauplius is large and bulky. columnar). Naupliar stages 2–3 have a long dorsal Food: Filter and suspension feeder, eating thoracic spine and approximate naupliar sizes plankton and detritus that is strained by cirri. are 350 µm (stage II), 350 µm (stage III), 450 Predators: Heavily preyed upon by sea stars µm (stage IV), 550 µm (stage V) and 650 µm (e.g Pisaster), particularly in its lower range (stage VI) (Fig. 14, Arnsberg 2001). The final (Cochran 1968). Other predators include the larval stage in cirripeds is called a cyprid, a nemertean Emplectonerna gracile, birds (e.g. non-feeding stage that attaches to a substrate Larus glaucescens, Haematopus bachmani, by its antennae, secretes a cement and builds Corvus caurinus, Wootton 1997), and the the adult calcareous shell (Ricketts and whelk, Nucella freycineti (Noda 2004). Three Calvin 1971). Cyprids are oblong and snail species, Thais emarginata, Thais composed of a bivalve shell, six thoracic canaliculata and Thais lamellosa are also appendages, a pair of compound eyes and a common predators of B. glandula and S. conspicuous lipid reserve anteriorly (Fig. 3, cariosus (Washington, Connell 1970; Sebens Arnsberg 2001; Figs. 22.2–22.3, Chan et al. and Lewis 1985). Furthermore, it has been 2014). Cyprids prefer rough surfaces for suggested that predation by this genus of settlement (Yonge 1963). Cyprid larvae in S. drilling gastropods has driven the evolution of cariosus are found in plankton in the spring balanomorph barnacle plate morphology and summer. They are large (960–1200 µm) (Palmer 1982). and with smooth carapace, bear no pigment Behavior: Barnacles detect changes in light spots (compare to Balanus crenatus, this with photoreceptors in simple eyes and in S. guide), and are angular both anteriorly and cariosus, the medial ocellus contains 6–9 posteriorly (Fig. 15, Arnsberg 2001). Cyprids photoreceptors (Millecchia and Gwilliam tend to settle into dark crevices from April– 1972). Furthermore, cirral beating in S. June (San Juan Archipelago, Washington, cariosus appears to be photoperiodic, where Høeg et al. 1987). Like other marine cirral activity is higher at night than during the invertebrate larvae, the cyprid larvae of S. day (Takeda et al. 1998). cariosus and B. glandula become concentrated in convergence zones over internal waves, which provides a mechanism Bibliography for shoreward transport of larvae prior to ARNSBERG, A. J. 2001. Arthropoda, settlement (Shanks and Wright 1987). Cirripedia: The Barnacles. In: An Juvenile: Usually up to 10 mm, juveniles are identification guide to the larval marine star-shaped and with 2–3 prominent ribs on invertebrates of the Pacific Northwest. carina, one on carinolateral and three or four A. L. Shanks (ed.). Oregon State on lateral and rostrum. Orifice very small University Press. (Henry 1940) and surrounded by numerous BRANSCOMB, E. S., and K. VEDDER. 1982. fine setae in newly metamorphosed A description of the naupliar stages of individuals. Young juveniles occurs from May the barnacles Balanus glandula to November (Puget Sound, Washington, (Darwin), Balanus cariosus (Pallas), Høeg et al. 1987). and Balanus crenatus (Bruguiere) Longevity: Longevity ranges from three (Cirripedia, Thoracica). Crustaceana. years in low intertidal (Ricketts and Calvin 42:83-95. 1971) to 10–15 years (Newman and Abbott CHAN, B. K. K., J. T. HØEG, and R. KADO. 1980). 2014. Thoracica, p. 116-124. In: Atlas

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