Botrylloides violaceus explained

Botrylloides violaceus is a colonial ascidian. It is commonly known as the chain tunicate,^[1] but has also been called several other common names, including: lined colonial tunicate, orange sheath tunicate, orange tunicate, and violet tunicate.^[2] Its native range is in the northwest Pacific from southern China to Japan and Siberia.^[3] Colonies grow on solid substrates and consist of individuals arranged in twisting rows. Outside its native range, it is considered an invasive species and is becoming more common in coastal waters of North America and other waters around the world, likely being spread by shipping industries.^[4]

In the San Francisco Bay area, B. violaceus can be readily found on boat docks in the Richmond Marina.^[5] The ecological impact of B. violaceus in this region remains unknown.

Morphology

Zooids are embedded in a transparent tunic and connected by a network of blood vessels that terminate in ampullae (small sac-like structures) at the periphery of the colony. Colony color varies from bright orange to reddish or dull purple. These tunicates usuallyhave 8 branchial tentacles and 11 rows of stigmata.^[6]

Significance and Interest

Colonial ascidians are the only known chordates capable of regenerating all body tissues. Because of chordates' close developmental relationship to vertebrates,^[7] the regenerative processes in colonial ascidians are of great interest to researchers. Whole body regeneration can be observed in B. violaceus after removal of all body tissues except the peripheral vasculature, suggesting the presence of circulating pluripotent or totipotent stem cells in the blood.^{[8] [9]} The first draft genome of B. violaceus was published in 2023.^[10]

Notes and References

1. Web site: Invasive tunicates in the Pacific Northwest . Lorne Curran and Samuel Chan . Oregon Sea Grant.
2. Web site: Purple Colonial Tunicate (Botrylloides violaceus) . WhatsThatFish.
3. Web site: Botrylloides violaceus . 2009-03-03 . Guide to the Exotic Species of San Francisco Bay . Cohen . Andrew N. . 2005. San Francisco Estuary Institute.
4. Web site: NAS - Species FactSheet (Botrylloides violaceus) . 2008-03-14 . Pam . Fuller . 2006-04-24 . USGS Nonindigenous Aquatic Species Database, Gainesville, FL. .
5. Web site: A Survey of Non-indigenous Aquatic Species in San Francisco Bay Updated July 2009 California Department of Fish and Game / Office of Spill Prevention and Response San Jose State University Foundation / Moss Landing Marine Laboratories . Stephen Foss .
6. Web site: Fact sheet 15 . 2009-03-04 . NON-INDIGENOUS AQUATIC SPECIES OF CONCERN FOR ALASKA . 2004 . . dead . https://web.archive.org/web/20101127064728/http://pwsrcac.org/docs/d0016000.pdf . 2010-11-27 .
7. Delsuc. Frédéric. Brinkmann. Henner. Chourrout. Daniel. Philippe. Hervé. 23 February 2006. Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature. en. 439. 7079. 965–968. 10.1038/nature04336. 16495997. 2006Natur.439..965D. 4382758. 1476-4687.
8. Brown . Federico . Whole body regeneration in a colonial ascidian, Botrylloides violaceus . Journal of Experimental Zoology Part B: Molecular and Developmental Evolution . 312B . 8 . 885–900 . 10.1002/jez.b.21303 . 19588490 . 2009 .
9. Rinkevich . B . Whole-body protochordate regeneration from totipotent blood cells . Proceedings of the National Academy of Sciences . 92 . 17 . 7695–7699 . 10.1073/pnas.92.17.7695 . 1995 . 41212 . 11607571. 1995PNAS...92.7695R . free .
10. Sumner . Jack T . Andrasz . Cassidy L . Johnson . Christine A . Wax . Sarah . Anderson . Paul . Keeling . Elena L . Davidson . Jean M . 2023-08-09 . De novo genome assembly and comparative genomics for the colonial ascidian Botrylloides violaceus . G3: Genes, Genomes, Genetics . 13 . 10 . 10.1093/g3journal/jkad181 . 2160-1836 . 10542563 . 37555394.