The body of Ciona is bag-like and covered by a tunic, which is a secretion of the epidermal cells. The body is attached at a permanent base located at the posterior part, and the opposite bears two openings, the buccal (oral) and atrial (cloacal) siphons. The water is drawn into the ascidian through the buccal siphon and leaves the atrium through the atrial siphon.
C. intestinalis is a hermaphrodite that releases sperm and eggs almost simultaneously into the surrounding seawater. C. intestinalis is self-sterile and thus has been used for studies on the mechanism of self-incompatibility. C. savigny is highly self-fertile, but non-self sperm out-compete self-sperm in fertilization competition assays. Mechanisms promoting non-self fertilization may have evolved to avoid inbreeding depression, and to facilitate outcrossing which allows the masking of deleterious recessive mutations.
- Sawada H, Morita M, Iwano M (August 2014). "Self/non-self recognition mechanisms in sexual reproduction: new insight into the self-incompatibility system shared by flowering plants and hermaphroditic animals". Biochem. Biophys. Res. Commun. 450 (3): 1142–8. doi:10.1016/j.bbrc.2014.05.099. PMID 24878524.
- Jiang D, Smith WC (October 2005). "Self- and cross-fertilization in the solitary ascidian Ciona savignyi". Biol. Bull. 209 (2): 107–12. doi:10.2307/3593128. PMID 16260770.
- Bernstein H, Byerly HC, Hopf FA, Michod RE (September 1985). "Genetic damage, mutation, and the evolution of sex". Science 229 (4719): 1277–81. doi:10.1126/science.3898363. PMID 3898363.
- The Tunicate Portal, an access point to the main websites and databases dealing with tunicates
- Ascidians.com, pictures of species around the world
- ANISEED, a model organism database for several ascidians species including Ciona intestinalis and Halocynthia roretzi
- JGI Ciona intestinalis v2.0, genome sequence
- View the Ciona intestinalis genome in the Ensembl genome browser .
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