Botrylloides Violaceus Class: Ascidiacea

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

Phylum: Chordata, Tunicata

Botrylloides violaceus Class: Ascidiacea

Order: Stolidobranchia A colonial ascidian, or tunicate Family: Styelidae

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

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected]

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.

up by colonial tunic (Zaniolo et al. 1998). Because of the shape of the colony, Botryllus Testes mulberry-like, anterior to ovum (Fig. zooids tend to be tear-shaped, with a 3a). (Not visible in zooid in Fig. 3.) “languet” or tongue-shaped atrial end and a Digestive Tract: To left of branchial sac, narrow, pointed end directed inward (Van with narrow loop at base (Berrill 1947) (Figs. Name 1945) (Fig. 5). Botrylloides zooids are 3, 3a.) usually oval-shaped, with the narrow end Larva: Large, up to 3mm in length, “tadpole” pointing outward (Carver et al. 2006). Botryl- type, with long posterior tail containing noto- lus individuals lack the brood pouch of Botryl- chord and slender neural tube. Body con- loides and their young develop in the atrium tains photolith, a balance and light organ before being extruded. A further difference near eye, and 24-34 ampullae (Fig. 4a) between the two species is that Botryllus has (Saito et al. 1981, Lambert 2003). the ovaries anterior to the testes (the reverse of Botrylloides), and can have one or several Possible Misidentifications ovaries; Botrylloides has one large ovary on The family Styelidae contains both each side. solitary and compound forms. Family char- Botrylloides violaceus has been con- acteristics include square or four-lobed ap- fused with the European B. leachi, B. au- ertures, simplfiliform tentacles, a continuous reum, as well as B. diegensis, a southern dorsal lamina (Fig. 3a), and straight longitu- California form, with brown and purple zooids dinal stigmata. Some genera have four and test vessels. This has made the inva- curved longitudinal folds in the pharynx, but sion of this species difficult to track. Van Botrylloides and the closely related Botryl- Name (1945) discusses Botrylloides mag- lus and Metandrocarpa do not (Van Name num from Alaska, but it is very large, and 1945). Four other genera also lack these poorly described. Cohen and Carlton (1995) longitudinal folds, but do not occur in our documented B. violaceus in the San Francis- area: Symplegma, Kukenthalia, Polyzoa co Bay as early as 1973. Botrylloides vio- and Alloeocarpa (Van Name 1945). laceus has been established in Coos Bay Of the three local encrusting colonial since the at least the late 1980s, when it was Styelidae, Metandrocarpa (dura) is usually documented in a comprehensive study of reddish, with large zooids (5-6 mm). It is not macro-fouling fauna in the bay (Hewitt 1993). arranged in systems: each zooid has a sep- arate atrial siphon. Zooids are more sepa- Ecological Information rate and distinct, being embedded in the Range: Genus worldwide tunic. Zooids can seem to be in rows and Local Distribution: Coos Bay: Charleston laterally fused, but are only connected ba- Inner and Outer Boat Basins, South Slough, sally. Coos Bay city docks. Population introduced to Botryllus spp., a cosmopolitan ge- Isthmus Slough via transplanted dock in 1990, nus, is often found with Botrylloides on no longer present (Hewitt 1993). floats, and the two can be difficult to distin- Habitat: On floating docks (Coos Bay); in guish. Botryllus always forms circular or bays and harbors (Abbott and Newberry star-shaped clusters or systems and never 1980). Ascidians represent a significant per- has more than 20 zooids in a system. centage of the fouling organism community Botrylloides forms systems composed of (Miller 1971, Simkanin et al. 2012). long double rows or clumps of zooids, and Salinity: Tolerance range 20-32, optimal often has several dozen zooids in a system. growth at 32 (Epelbaum et al. 2009b). Collect-

ed at 15.6-37.8 (Coos Bay, Dorning pers. highest recruitment in late spring and early obs.). summer. Prolonged periods of warmer tem- Temperature: Global temperature range of peratures extends reproductive period by initi- 0.6-29.3°C (Zerebecki and Sorte 2011). 10- ating earlier onset of recruitment (Powell 18 °C (Coos Bay, Dorning pers. obs.). Geo- 1970; Ross and McCain 1976; Stachowicz et graphical variation in maximum temperature al. 2002; Epelbaum et al. 2009a; Dijkstra et al. tolerance (West coast: 25°C) (Sorte et al. 2011). Larval settlement in Coos Bay peaks 2011). between July and September (Hewitt 1993) Tidal Level: Low intertidal and shallow sub- during periods of low recruitment by native tidal (Abbott and Newberry 1980). Restricted species (Stachowicz and Byrnes 2006). Lar- to depths less than 50m (Carver et al. 2006). vae release determined by light and released Associates: Obelia, caprellid amphipods, between 8am-12pm in Charleston harbor Corophium amphipods, nereid polychaetes, (Marshall et al. 2006). spirorbid polychaetes, Eudistylia, Botryllus Asexual reproduction can happen in schlosseri. Found overgrowing Schizoporel- two ways. Buds can develop from parent zo- la unicornis, Watersipora subtorquata, oids via palleal/propagative budding (Fig. 3), Balanus spp. and Mytilus spp (Hewitt 1993; which occurs continuously to replace transient Dorning pers. obs.). Can overgrow and be zooid structures and to grow laterally. In the overgrown by Halichondria bowerbanki. As- absence of adult zooids, and in adverse envi- cidians are commensal hosts to notodelphid ronmental conditions, growth can occur at the copepods, amphipods, and host to some bases of vascular ampullae (Nakauchi 1982; specific parasitic copepods (Miller 1971), but Carver et al. 2006; Kurn et al. 2011). Numer- resistant to epibiotic larval recruitment ous buds of all types abort during develop- (Hewitt 1993). ment, and one colony may be comprised of Abundance: Locally common on floating adult zooids, primary palleal buds, and sec- docks, especially in summer. Peak settle- ondary buds connected to primary buds ment abundance observed in April (Point (Carver et al. 2006). Fragmentation of colo- Adams Jetty and North Jetty) (Hewitt 1993). nies results in reattachment to substrate and subsequent asexual budding as multiple colo- Life-History Information nies (Agius 2007). Contact between two adja- Reproduction: Hermaphroditic and ovovi- cent colonies can result in fusion to form a viparous. Asexual budding also occurs. Sex- single chimera (Cima et al. 2004). ual fertilization internal, embryos develop in Larva: ovary (one to a zooid, 1-1.5mm diameter), Juvenile: and emerge as tadpoles after a one-month Longevity: An ascidian colony may live more gestational period (Takeuchi 1980; Saito et than three years and an individual zooid for al. 1981, Zaniolo et al. 1998). Parent zooids five to seven days before undergoing apopto- disintegrate 5 days after ovulation and only sis and being replaced by new asexual buds brood pouches containing larvae remain (Berrill 1947; Brown et al. 2009; Kurn et al. (Mukai et al. 1987). Larvae develop quickly, 2011). settle soon (within minutes to hours) and Growth Rate: First generation of blastozooids metamorphose to form functional oozooids, develop to form a functional colony after 7-10 from which blastozooids develop asexually days. Asexual growth rate highly variable (Fig. 4) (Takeuchi 1980; Saito et al. 1981). (Epelbaum et al. 2009a); oozooids observed Sexual reproduction occurs year-round, with to grow 1.9 mm within a week before produc-

ing buds asexually (Yamaguchi 1975). effects of pre-seeding plates with invasive Growth rate increases at higher tempera- ascidians: growth, recruitment and com- tures (19.1-23.3°C) (Stachowicz et al. 2002); munity composition. Journal of Experi- coolest peak growth at 14°C (Lord and Whit- mental Marine Biology and Ecology. latch 2015). 342:30-39. Food: Ciliary mucus feeders, filtering plank- 3. BERRILL, N. J. 1947. The developmental ton through the tentacles. cycle of Botrylloides. The Quarterly Jour- Predators: No natural predators observed, nal of Microscopical Science. 88:393-407. possibly due to chemical unpalatability. On- 4. BROWN, F. D., E. L. KEELING, A. D. LE, ly vulnerable to potential predation a short and B. J. SWALLA. 2009. Whole body re- period after settlement (days to a week), generation in a colonial ascidian, Botryl- (Pisut and Pawlik 2002; Tarjuelo et al. loides violaceus. Journal of Experimental 2002). Experimental exclusion of potential Zoology: Part B-Molecular and Develop- chiton, gastropod and flatworm predators mental Evolution. 312B:885-900. does not affect B. violaceus recruitment or 5. CARVER, C. E., A. L. MALLET, and B. abundance (Grey 2010). Potential sea star, VERCAEMER. 2006. Biological synopsis crab, nudibranch, and urchin predators pre- of the colonial tunicates (Botryllus fer natural prey to B. violaceus (Epelbaum et schlosseri and Botrylloides violaceus). Ca- al. 2009b). Ascidian predators include fish, nadian Manuscript Report of Fisheries and crab, polychaetes, sea stars; especially Aquatic Sciences. 2747:1-42. prosobranch molluscs, opisthobranchs, nu- 6. CIMA, F., A. SABBADIN, and L. BALLAR- dibranchs, turbellarian flatworms and the IN. 2004. Cellular aspects of allorecogni- grey seal (Scotland). Used by man for food tion in the compound ascidian Botryllus (Japan, Mediterranean, Chile) and bait schlosseri. Developmental and Compara- (Australia, South Africa. Destroyed as a tive Immunology. 28:881-889. pest in oyster beds and commercial fishing 7. COHEN, A. N., and J. T. CARLTON. 1995. grounds (Miller 1971). Nonindigenous aquatic species in a United Behavior: Zooids are sessile. Tadpole lar- States estuary: a case study of the biologi- vae can swim, but tend to settle near par- cal invasions of the San Francisco Bay ents, attaching to substrate with adhesive and delta. National Sea Grant Program, papillae, perhaps due to chemical induction Connecticut. of settlement by adult colonies (Railkin 8. DIJKSTRA, J. A., E. L. WESTERMAN, 2004). Not particularly competitive in native and L. G. HARRIS. 2011. The effects of habitat (Japan) but competitively dominant climate change on species composition, in Coos Bay, overgrowing most native spe- succession and phenology: a case study. cies (Hewitt 1993). Global Change Biology. 17:2360-2369. 9. EPELBAUM, A., C. M. PEARCE, D. J. Bibliography BARKER, A. PAULSON, and T. W. THER- 1. ABBOTT, D. P., and A. T. NEWBERRY. RIAULT. 2009a. Susceptibility of non- 1980. Urochordata: The tunicates, p. 177 indigenous ascidian species in British Co- -226. In: Intertidal invertebrates of Cali- lumbia (Canada) to invertebrate predation. fornia. R. H. Morris, D. P. Abbott, and E. Marine Biology. 156:1311-1320. C. Haderlie (eds.). Stanford University 10. EPELBAUM, A., T. W. THERRIAULT, A. Press, Stanford, CA. PAULSON, and C. M. PEARCE. 2009b. 2. AGIUS, B. P. 2007. Spatial and temporal Botryllid tunicates: culture techniques and

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