Ascidia liberata   Sluiter,  1887 (Sea Squirt)
Organism information awaits expert curation
Class: Ascidiacea

Image copyrights: The Marine Biological Association of India

Size: 4.5-6 cm long and 2.5-4 cm broad

Color: Transparent

Individual more or less rectangular, with the posterior end rounded, laterally flattened and attached by the whole of the left side. There is a prominent ridge present in arising from the outer edge of the base of the branchial siphon to the postero-dorsal comer of the body. The apertures are on very short conical siphons, but in the larger specimen, siphons are distinct and cylindrical. The branchial aperture sub-terminal and the atrial one-third from the anterior end on the dorsal surface. Both siphons are ridged, slightly raised and directed dorsally. The test is thick, cartilaginous, translucent with shallow transverse creases forming wrinkles. The large specimen has colonial ascidians as epibionts. There are 7 branchial and 6 atrial lobes. Tentacular fringes are absent from the lobes in line with and on either side of the dorsal tubercle. The other lobes have well developed fringes.

The body wall is thin, delicate, reddish brown in color. Well developed circular muscles in the siphons. Longitudinal muscles radiate from the branchial siphon onto the right side. These muscles with the transverse muscles between the siphons form a mesh on the right side in the region between the siphons. The longitudinal muscles from the atrial siphon become gradually thin. There is a prominent mid-dorsal and marginal band of transverse muscles posterior to the atrial siphon. The space between these two bands has thin longitudinal muscles. On the left side, muscles are present only anterior to the gut loop. More than 90 tentacles present are very long, medium and short. Prebranchial area is narrow. No peritubercular area. The dorsal tubercle has a V-shaped opening with both horns turned in. Neural gland is situated 1.2 cm from the posterior end of the dorsal tubercle. Dorsal lamina is ribbed, with the ribs projecting slightly from the free edge and double anteriorly. Branchial sac has shallow pleats. Branchial papillae are rounded with a projection at their base. Intermediate branchial papillae are present at many places in the posterior region of the branchial sac. 4-5 stigmata in a mesh. The gut loop deeply curved and occupies three quarters of the left side. The margin of the anterior pole of the gut loop lies above the anterior margin of the atrial aperture. Anus is in line with the middle of the atrial aperture. Primary gut loop is deep and open at the pole. The axis of the secondary gut loop passes near the pyloric end of the stomach. The intestine is distended with mud. Anal border is smooth. Ovary is highly branched. The testis follicles lie in the gut loop.

Similar species: This species resembles Ascidia sydneiensis Stimpson, 1855 in the position of the neural ganglion near the dorsal tubercle, the tentacular fringe on the lobes of apertures and a border of transverse muscles around the right side of the body. However, the present species is distinguished by the absence of tentacular fringes from the lobes in line with and on either side of the dorsal tubercle, a mesh of muscles in the region between the siphons and a marginal band of transverse muscles posterior to the atrial siphon with very thin longitudinal muscles between them and in the presence of a smooth anus. Ascidia nerea Kott, 1985 has a similar arrangement of muscles and a smooth anus, but the present species is distinguished from Ascidia nerea by the presence of tentacular fringes on the lobes of apertures, lesser number (90) of branchial tentacles (compared to 200 in Ascidia nerea), presence of shallow pleats in the branchial sac, more than 3 stigmata in a mesh, intermediate branchial papillae in many places in the posterior region of the branchial sac and a mud-distended intestine.

Synonym (s)
Ascidia dorsalis Monniot, 1987
Ascidia solomonensis Nishikawa, 1986

Common Name (s)
Economic Importance and Threats

Habitat:  Benthic, Demersal, Rocky, Coastal


• Kerala, Vizhinjam Bay INDIA
• Kerala, Vizhinjam Fishing Harbour INDIA

Literature Source(s)
  • Meenakshi, VK (2005) Addition to the ascidian fauna of India Journal of the Marine Biological Association of India Marine Biological Association of India, Cochin 47(1) 36-49 Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Abdul, JAH and Sivakumar, V (2007) Occurrence and distribution of ascidians in Vizhinjam Bay (south west coast of India) Journal of Experimental Marine Biology and Ecology 342(1) 189-190 Available at -
  • Sealifebase Available at -
  • Meenakshi, VK; Renganathan, TK; Senthamarai, S and Jeyalakshmi, J (2003) Marine biodiversity - Taxonomy of Indian Ascidians Technical report Available at - Biodiversity Informatics Group, NIO, Goa

Page last updated on:2011-02-22

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