Ciona intestinalis (sometimes known by the common name of vase tunicate) is an ascidian (sea squirt), a tunicate with very soft tunic. Its Latin name literally means "pillar of intestines", referring to the fact that its body is a soft, translucent column-like structure, resembling a mass of intestines sprouting from a rock.[1] It is a globally distributed cosmopolitan species. Since Linnaeus described the species, Ciona intestinalis has been used as a model invertebrate chordate in developmental biology and genomics.[2] Studies conducted between 2005 and 2010 have shown that there are at least two, possibly four, sister species.[3][4][5] More recently it has been shown that one of these species has already been described as Ciona robusta.[6] By anthropogenic means, the species has invaded various parts of the world and is known as an invasive species.[7][8]
Although Linnaeus first categorised this species as a kind of mollusk, Alexander Kovalevsky found a tadpole-like larval stage during development that shows similarity to vertebrates. Recent molecular phylogenetic studies as well as phylogenomic studies support that sea squirts are the closest invertebrate relatives of vertebrates.[9] Its full genome has been sequenced using a specimen from Half Moon Bay in California, US,[10] showing a very small genome size, less than 1/20 of the human genome, but having a gene corresponding to almost every family of genes in vertebrates.
^Zhan, A; Macisaac HJ; Cristescu ME (2010). "Invasion genetics of the Ciona intestinalis species complex: from regional endemism to global homogeneity". Molecular Ecology. 19 (21): 4678–4694. doi:10.1111/j.1365-294x.2010.04837.x. PMID20875067. S2CID205363202.
^Blum, J.C.; Chang, AL.; Liljesthröm, M.; Schenk, M.E.; Steinberg, M.K.; Ruiz, G.M. (2007). "The non-native solitary ascidian Ciona intestinalis (L.) depresses species richness". Journal of Experimental Marine Biology and Ecology. 342: 5–14. doi:10.1016/j.jembe.2006.10.010.
^Herridge, Paul (June 11, 2013). "The vase tunicate has landed". The Southern Gazette. Marystown, Newfoundland and Labrador. Archived from the original on June 28, 2013. Retrieved June 26, 2013.