Ascidia kesavanica     (Sea Squirt)
Organism information awaits expert curation
Class: Ascidiacea

Image copyrights: The Marine Biological Association of India

Individuals measuring 3.5 cm long and 2 cm broad, oval, posterior end round to flattened, laterally compressed and attached by the whole of the left side. The anterior end is slightly depressed on which the distinct, short and ridged siphons are present directed antero-dorsally. The siphons are long and tubular, branchial siphon on the anterodorsal end and atrial siphon one-third from the anterior end on the dorsal surface. The test is thick, cartilaginous, firm and translucent grey with wrinkles especially in the anterior region and sparsely distributed papillae with a terminal branch of the test vessel. The posterior half of the test is smooth. Epibionts like compound ascidian (Symplegma viride) were found. There are 7 branchial and 6 atrial lobes. The lobes are with minute tentacular projections.

The body wall is thin, delicate and reddish yellow especially around siphons. The musculature consists of circular muscles around the siphons. Longitudinal muscles extend from the apertures, along with the oblique muscles form a mesh on the right side of the body. This mesh is peculiar in that it is prominent only in the anterior half of the right side. The muscles gradually thin out below the level of the atrial siphon; completely disappear towards the posterior and postero-ventral side. On the left side muscles do not extend beyond the gut loop. Branchial tentacles 45-50, of three different orders, long, medium and short (but not very short ones). The prebranchial area is narrow and not papillated. A V-shaped peritubercular area absent and there is a shallow depression where the dorsal tubercle is lodged. It has a V-shaped slit with both horns turned in. Dorsal ganglion close to the dorsal tubercle. Dorsal lamina is a broad ribbed membrane with the ribs slightly projecting beyond the membrane. The free ends of the membrane between the ribs are raised into minute fringes. The membrane is rolled towards the left. The branchial sac is pleated with 40 internal longitudinal vessels on the left side and 5-6 on the right side. The branchial papillae are elongate with slight projections on both sides of their base. Intermediate branchial papillae present regularly. The meshes are rectangular with 5-6 stigmata in a mesh. The gut occupies almost the whole of the left side. Anterior margin of the gut loop is far anterior to the base of the atrial siphon. The primary gut loop is deep and slightly open only at the pole and the axis of the secondary gut loop, passes through the middle of the stomach. The bilobed, laterally compressed anus is very near to the atrial aperture below the anterior margin of the gut loop. The test vessel emanates from about the posterior half of the ventral side. Gonads are in the gut loop. Ovary has short branches almost throughout its entire length. Testis follicles are present in the gut loop and spread over the intestine.

Similar species: This species resembles Ascidia depressiuscula Herdman, 1906, in the shape of the body, site of attachment to the substratum, opening of the neural gland with both horns coiled inwards, 5­-6 stigmata in a mesh, intermediate bran­chial papilla, neural ganglion close to the dorsal tubercle and a ribbed dorsal lamina with small marginal denticulations.

Synonym (s)

Common Name (s)
Economic Importance and Threats



• INDIA (Record: 2005)

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 -

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