Botrylloides Violaceus Class: Ascidiacea Order: Stolidobranchia a Colonial Ascidian, Or Tunicate Family: Styelidae

Home , Botrylloides, Botrylloides violaceus, Botryllus, Polyzoa (tunicate), Stolidobranchia, Styelidae

Phylum: Chordata Botrylloides violaceus Class: Ascidiacea Order: Stolidobranchia A colonial ascidian, or tunicate Family: Styelidae

Description Size: Colonies range in size from several to Cloaca: Common, between rows of zooids 50 cm across (Abbott and Newberry 1980; (Figs. 1a, 2a). Atrial apertures of zooids are Saito et al. 1981; Carver et al. 2006); below surface of colony (Fig. 3a). individual zooids are 1-2 mm long (as seen Pharynx: Branchial sac or pharyngeal from above) and about half as wide as they basket, which posteriorly leads to esophagus, are long (Fig. 1). Zooids occur in ladder-like stomach, and intestine. This structure rows or "systems” and dozens to hundreds of contains stigmata (stilts) and cilia for filtering individual zooids make up a flat, encrusting food. It has 3 inner long vessels or bars, but colony (Carver et al. 2006). Each zooid has no longitudinal folds separating stigmata an independent siphon opening into a (Berrill 1947) (Fig. 3a). Species lacks an common cloacal cavity between rows (Fig. 1) abdomen and body not divided as in some (Carver et al. 2006). elongate solitary ascidians (Fig. 3). Color: Can be purple, pink, yellow, or orange Endostyle: A deep groove on ventral side of (Epelbaum et al. 2009a) and color may pharynx (side opposite atrial siphon), possibly be light dependent (Berrill 1947). containing long glandular bands which Current specimen (Coos Bay) light yellow- produce mucus used for feeding (Berrill 1947) orange to red. “Test” (see below) clear. (Fig. 3a). Zooids: Oblong, more or less free (Lambert Dorsal Lamina: A membranous ridge, 2003) and each with a raised oral aperture. projecting inward from the dorsal midline of Cloaca shared by zooids across row. With the pharynx (atrial siphon side) (Fig. 3a). one large ovary on each side of body: genus Dorsal lamina rolls mucus sheets into a cord, Botrylloides (Van Name 1945). Asexual buds after receiving them from endostyle across develop on zooid walls or from ampullae sac walls (Goodbody 1974). (vascular buds) at colony edges (Figs. 1a, 3). Stigmata: Groups of slits in pharynx walls Incubating pouches develop from ovaries: between longitudinal vessels (Figs. 1, 3, 3a). genus Botrylloides (Abbott and Newberry Atrium: Cavity surrounding pharynx. Water 1980). enters atrium via stigmata, and exits by atrial Tunic or Test: An external connective tissue, siphon (Fig. 3a). transparent in these specimens. Gonads: One ovary on each side of zooid Mantle: The true body wall: a thin, sac-like (Fig. 3a) (Saito et al. 1981). Egg fertilized and membrane inside test, containing muscle and embryo develops in brood pouch in ovum blood vessels, and enclosing the internal (Mukai et al. 1987). Brood pouch eventually parts (Van Name 1945) (Fig. 3a). detaches from atrial epithelium and is taken Ampullae: Enlarged, finger-shaped, blind up by colonial tunic (Zaniolo et al. 1998). blood reservoirs around edges of tunic. Can Testes mulberry-like, anterior to ovum (Fig. give rise to new zooids by vascular budding. 3a). (Not visible in zooid in Fig. 3.) Ampullae also have a respiratory function. Digestive Tract: To left of branchial sac, with Oral Aperture: Round, raised and smooth- narrow loop at base (Berrill 1947) (Figs. 3, edged on anterior surface with small simple 3a.) tentacles and four-lobed siphon inside (Fig. Larva: Large, up to 3mm in length, “tadpole” 1). type, with long posterior tail containing Tentacles: Simple; four large and several notochord and slender neural tube. Body small (these specimens) (Fig. 1). contains photolith, a balance and light organ near eye, and 24-34 ampullae (Fig. 4a) (Saito et al. 1981, Lambert 2003).

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12927 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Possible Misidentifications discusses Botrylloides magnum from Alaska, The family Styelidae contains both solitary but it is very large, and poorly described. and compound forms. Family characteristics Cohen and Carlton (1995) documented B. include square or four-lobed apertures, violaceus in the San Francisco Bay as early simplfiliform tentacles, a continuous dorsal as 1973. Botrylloides violaceus has been lamina (Fig. 3a), and straight longitudinal established in Coos Bay since the at least the stigmata. Some genera have four curved late 1980s, when it was documented in a longitudinal folds in the pharynx, but comprehensive study of macro-fouling fauna Botrylloides and the closely related Botryllus in the bay (Hewitt 1993). and Metandrocarpa do not (Van Name 1945). Four other genera also lack these longitudinal Ecological Information folds, but do not occur in our area: Range: Genus worldwide Symplegma, Kukenthalia, Polyzoa and Local Distribution: Coos Bay: Charleston Alloeocarpa (Van Name 1945). Inner and Outer Boat Basins, South Slough, Of the three local encrusting colonial Coos Bay city docks. Population introduced to Styelidae, Metandrocarpa (dura) is usually Isthmus Slough via transplanted dock in reddish, with large zooids (5-6 mm). It is 1990, no longer present (Hewitt 1993). not arranged in systems: each zooid has a Habitat: On floating docks (Coos Bay); in separate atrial siphon. Zooids are more bays and harbors (Abbott and Newberry separate and distinct, being embedded in the 1980). Ascidians represent a significant tunic. Zooids can seem to be in rows and percentage of the fouling organism laterally fused, but are only connected community (Miller 1971, Simkanin et al. basally. 2012). Botryllus spp., a cosmopolitan genus, is Salinity: Tolerance range 20-32, optimal often found with Botrylloides on floats, and growth at 32 (Epelbaum et al. 2009b). the two can be difficult to distinguish. Botryllus Collected at 15.6-37.8 (Coos Bay, Dorning always forms circular or star-shaped clusters pers. obs.). or systems and never has more than 20 Temperature: Global temperature range of zooids in a system. Botrylloides forms 0.6-29.3C (Zerebecki and Sorte 2011). 10-18 systems composed of long double rows or °C (Coos Bay, Dorning pers. obs.). clumps of zooids, and often has several Geographical variation in maximum dozen zooids in a system. Because of the temperature tolerance (West coast: 25C) shape of the colony, Botryllus zooids tend to (Sorte et al. 2011). be tear-shaped, with a “languet” or tongue- Tidal Level: Low intertidal and shallow shaped atrial end and a narrow, pointed end subtidal (Abbott and Newberry 1980). directed inward (Van Name 1945) (Fig. 5). Restricted to depths less than 50m (Carver et Botrylloides zooids are usually oval-shaped, al. 2006). with the narrow end pointing outward (Carver Associates: Obelia, caprellid amphipods, et al. 2006). Botryllus individuals lack the Corophium amphipods, nereid polychaetes, brood pouch of Botrylloides and their young spirorbid polychaetes, Eudistylia, Botryllus develop in the atrium before being extruded. schlosseri. Found overgrowing Schizoporella A further difference between the two species unicornis, Watersipora subtorquata, Balanus is that Botryllus has the ovaries anterior to the spp. and Mytilus spp (Hewitt 1993; Dorning testes (the reverse of Botrylloides), and can pers. obs.). Can overgrow and be overgrown have one or several ovaries; Botrylloides has by Halichondria bowerbanki. Ascidians are one large ovary on each side. commensal hosts to notodelphid copepods, Botrylloides violaceus has been confused amphipods, and host to some specific with the European B. leachi, B. aureum, as parasitic copepods (Miller 1971), but resistant well as B. diegensis, a southern California to epibiotic larval recruitment (Hewitt 1993). form, with brown and purple zooids and test vessels. This has made the invasion of this species difficult to track. Van Name (1945)

Dorning, S.L. 2017. Botrylloides violaceus. 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. Quantitative Information 2007). Contact between two adjacent Weight: colonies can result in fusion to form a single Abundance: Locally common on floating chimera (Cima et al. 2004). docks, especially in summer. Peak settlement Growth Rate: First generation of abundance observed in April (Point Adams blastozooids develop to form a functional Jetty and North Jetty) (Hewitt 1993). colony after 7-10 days. Asexual growth rate highly variable (Epelbaum et al. 2009a); Life History Information oozooids observed to grow 1.9 mm within a Reproduction: Hermaphroditic and week before producing buds asexually ovoviviparous. Asexual budding also occurs. (Yamaguchi 1975). Growth rate increases at Sexual fertilization internal, embryos develop higher temperatures (19.1-23.3C) in ovary (one to a zooid, 1-1.5mm diameter), (Stachowicz et al. 2002); coolest peak growth and emerge as tadpoles after a one-month at 14C (Lord and Whitlatch 2015). gestational period (Takeuchi 1980; Saito et al. Longevity: An ascidian colony may live more 1981, Zaniolo et al. 1998). Parent zooids than three years and an individual zooid for disintegrate 5 days after ovulation and only five to seven days before undergoing brood pouches containing larvae remain apoptosis and being replaced by new asexual (Mukai et al. 1987). Larvae develop quickly, buds (Berrill 1947; Brown et al. 2009; Kurn et settle soon (within minutes to hours) and al. 2011). metamorphose to form functional oozooids, Food: Ciliary mucus feeders, filtering from which blastozooids develop asexually plankton through the tentacles. (Fig. 4) (Takeuchi 1980; Saito et al. 1981). Predators: No natural predators observed, Sexual reproduction occurs year-round, with possibly due to chemical unpalatability. Only highest recruitment in late spring and early vulnerable to potential predation a short summer. Prolonged periods of warmer period after settlement (days to a week), temperatures extends reproductive period by (Pisut and Pawlik 2002; Tarjuelo et al. 2002). initiating earlier onset of recruitment (Powell Experimental exclusion of potential chiton, 1970; Ross and McCain 1976; Stachowicz et gastropod and flatworm predators does not al. 2002; Epelbaum et al. 2009a; Dijkstra et affect B. violaceus recruitment or abundance al. 2011). Larval settlement in Coos Bay (Grey 2010). Potential sea star, crab, peaks between July and September (Hewitt nudibranch, and urchin predators prefer 1993) during periods of low recruitment by natural prey to B. violaceus (Epelbaum et al. native species (Stachowicz and Byrnes 2009b). Ascidian predators include fish, crab, 2006). Larvae release determined by light and polychaetes, sea stars; especially released between 8am-12pm in Charleston prosobranch molluscs, opisthobranchs, harbor (Marshall et al. 2006) nudibranchs, turbellarian flatworms and the Asexual reproduction can happen in grey seal (Scotland). Used by man for food two ways. Buds can develop from parent (Japan, Mediterranean, Chile) and bait zooids via palleal/propagative budding (Fig. (Australia, South Africa. Destroyed as a pest 3), which occurs continuously to replace in oyster beds and commercial fishing transient zooid structures and to grow grounds (Miller 1971). laterally. In the absence of adult zooids, and Behavior: Zooids are sessile. Tadpole in adverse environmental conditions, growth larvae can swim, but tend to settle near can occur at the bases of vascular ampullae parents, attaching to substrate with adhesive (Nakauchi 1982; Carver et al. 2006; Kurn et papillae, perhaps due to chemical induction of al. 2011). Numerous buds of all types abort settlement by adult colonies (Railkin 2004). during development, and one colony may be Not particularly competitive in native habitat comprised of adult zooids, primary palleal (Japan) but competitively dominant in Coos buds, and secondary buds connected to Bay, overgrowing most native species (Hewitt primary buds (Carver et al. 2006). 1993). Fragmentation of colonies results in reattachment to substrate and subsequent asexual budding as multiple colonies (Agius

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