AquaNISInformation system on aquatic non-indigenous and cryptogenic species |
Species | Botrylloides violaceus [WoRMS] | |
Authority | Oka, 1927 | |
Family | Styelidae | |
Order | Stolidobranchia | |
Class | Ascidiacea | |
Phylum | Chordata | |
Synonym (?) | Violet Tunicate | |
Sub-species level (?) | Not entered |
Native origin (?) | Country: Japan References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. Comments: NW Pacific: Japan, southern Siberia to southern China |
Life form / Life stage (?) |
References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. Comments: Mature brooded larvae are evident through the translucent wall of the tunic. Then a tadpole larva is released. |
Sociability / Life stage (?) |
References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. (AND REFERENCES THEREIN) Comments: COLONIAL: small zooids arranged within a common gelatinous matrix or tunic. Bulk of the tunic is composed of tunicin, a polysaccharide similar to cellulose. Each zooid of the colony has an independent siphon opening into the common cavity. By sharing a common vascular system and common exhalent canal, this morphological arrangement maximizes the number of zooids in a given area. Campbell et al. (1999) suggested that by diverting their exhalent siphons into a common chamber, the colony effectively augments the force of the exiting current thereby ensuring that waste products and larvae repropulsed or dispersed away from the main colony. The zooids share a common vascular system that consists of blood vessels and enlarged sausage-shaped vascular ampullae along theperiphery (Milkman 1967, Brunetti and Burighel 1969). This gelatinous matrix has the capacity to reconstruct the colony by vascular budding if all the zooids are lost. |
Reproductive frequency (?) | Iteroparous References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. |
Reproductive type (?) | Asexual Sexual References: Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. Comments: ASEXUAL: budding SEXUAL: Male and female gonads are separateand located on either side of the body. B. violaceus has one ovary on either side of the body located posterior to the testes. Single eggs pass through the oviduct into a sac-like developmental or incubatory pouch that forms as an outgrowth of the body wall. |
Developmental trait (?) | Brooding Viviparous References: Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. Comments: B. violaceusnormally produces one 80-µm alecithal or non-yolky egg, but occasionally two, which are ovulated into the atrial cavity and lodged within a brood pouch in the tunic. The egg is fertilized within the brood pouch where it undergoes embryogenesis. In this viviparous species the brood pouch eventually becomes detached from the atrial epithelium and becomes incorporated in the colonial tunic. During the 1-mo gestation period the embryo receives nutrients from the blood flowing through the tunic; the embryos may reach 1-1.5 mm in diameter and are clearly evident through the wall of the tunic. Embryos in various stages of development may be observed within incubatory pouches in the same colony during the peak period of sexual reproduction (Saito et al. 1981). The mother zooids disintegrate approximately 5 d after ovulation, leaving only the brood pouches containing the developing larvae. In B. violaceusthe free-swimming tadpole larvae break through thewall of the incubatory pouch to reach the exterior of the colon. The larvae are huge (2-3 mm) with 24-32 ampullae (Figure 9b); they swim for only a brief period (4-10 h) before using their elongated ampullae to attach to a suitable settlement substrate. B. violaceus release their larvae at dawn, at which time they show marked positive phototaxis; larvae were observed to settle within a few hours of liberation. Larvae required only 1-2 d to attach and metamorphose into fully functional oozooids with branchial and atrial apertures. After 4-7 d blastozooids or buds develop at the base of the oozooids; at 7-10 d these blastozooids become functional and the primary oozooid degenerates. |
Characteristic feeding method / Life stage (?) |
References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. Comments: ascidians are known to be mucus filter feeders that can extract particles as small as 0.5 µm up to a limit set by the size of the oesophagus. The feeding currents are created by cilia in tracts located on either side of the stigmata in the walls of the branchial sac. Particles are collected on a mucus sheet that migrates by ciliary action across the internal surface of the branchial sac from where it is concentrated and directed into the stomach. |
Mobility / Life stage (?) |
References (not structured): Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. |
Salinity tolerance range (?) | Exact range: 20 - 38 References: Epelbaum A, L.M. Herborg, T.W. Therriault, C.M. Pearce (2009) Temperature and salinity effects on growth, survival, reproduction, and potential distribution of two non-indigenous botryllid ascidians in British Columbia. Journal of Experimental Marine Biology and Ecology 369: 43–52. Comments: Botrylloides violaceus tolerated environmental conditions between 20-38‰, but demonstrated positive growth and its largest colony sizes at 26-38‰ |
Habitat modifying ability potential (?) | Autogenic ecosystem engineers |
Toxicity / Life stage (?) | Not relevant |
Bioaccumulation association (?) | Anthropogenic chemical compounds References: Osborne, K.L., Poynton, H.C. 2019. Copper pollution enhances the competitive advantage of invasive ascidians. Management of Biological Invasions, 10(4), pp. 641–656 Comments: B. violaceus is more tolerant of copper pollution than A. glabrum in laboratory conditions. |
Known human health impact? | Not known |
Known economic impact? | Known References: Knorek, Z. R. 2018. A Tale of Two Tunicates: Didemnum Vexillum and Botrylloides Violaceus as Biofouling Agents in Aquaculture (Master's thesis, University of Oregon), 10828455. Arens, C. J., Paetzold, S. C., Ramsay, A., Davidson, J. 2011. Pressurized seawater as an antifouling treatment against the colonial tunicates Botrylloides violaceus and Botryllus schlosseri in mussel aquaculture. Aquatic Invasions, 6(4), pp. 465-476. Comments: Botrylloides violaceus had no impact on the growth, condition, or organic composition of oysters and mussels grown in a simulation of longline aquaculture. Invasive tunicates typically proliferate on artificial substrates such as rock walls, wharf pilings, navigational buoys, floating docks, vessel hulls, and aquaculture infrastructure. The use of high-pressure seawater was an effective anti-fouling measure for Botryllus schlosseri and Botrylloides violaceus. |
Known measurable environmental impact? | Known References: Gittenberger, A., Moons, J. J. S. 2011. Settlement and possible competition for space between the invasive violet tunicate Botrylloides violaceus and the native star tunicate Botryllus schlosseri in The Netherlands. Aquatic Invasions, 6(4), pp. 435-440. Comments: Settlement and competition for space of two colonial sea squirts, the non-native violet tunicate Botrylloides violaceus and the native golden star tunicate Botryllus schlosseri, were compared in The Netherlands.Botrylloides violaceus outcompeted Botryllus schlosseri for space. |
Included in the Target Species list? | No References: HELCOM, 2009. Alien Species and Ballast Water [PDF]. Available at: (https://archive.iwlearn.net/helcom.fi/stc/files/shipping/Table_2_Alienspecies_%20lists_2009.pdf) |
Association with vessel vectors (?) | Biofouling References: Carver, C.E., A.L. Mallet and B. Vercaemer. 2006. Biological Synopsis of the colonial tunicates, Botryllus schlosseri and Botrylloides violaceus. Can. Man. Rep. Fish. Aquat. Sci. 2747: v + 42 p. |
Last update by | Sandra Gečaitė, 2024-07-05 |