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

Image copyrights: The Marine Biological Association of India

Size: 3.5 cm long, 1.5 cm wide with a peculiar shape.

Body is laterally compressed and attached to the substratum by the flat left side. The anterior of the right side of the animal is raised high above the substratum. The right side of the body gradually slopes from anterior towards the posterior end. The posterior end is rounded. The anterior end is flattened and the short ridged branchial siphon lies on the extreme anterior right end lying high above and directed towards the substratum. The atrial siphon is at the anterior left end lying close to the substratum directed upwards. The zooid removed from the test has a moderately long branchial siphon and an atrial siphon almost twice the length of the branchial siphon. There are 7 branchial and 6 atrial lobes. Each lobe has 7 tentacular fringes and ocelli between them. The test is thin, cartilaginous, not brittle, slightly yellowish brown around the apertures in live specimen. Many transverse shallow creases are present forming wrinkles on the surface. Small papillae are distributed in the anterior part of the body, which become sparse and minute towards the posterior end. The main test of the vessel originates from the middle of the ventral side, branches profusely on the test surface and is without the spherical ampullae. The inner surface of the test has many overlapping, spherical markings, which are very vague on the outer surface.

The body wall is thin, reddish yellow near the siphons. There are circular muscles in the siphons. Longitudinal muscles extend from the siphon into the right side and along with the transverse muscles from a fine mesh arranged as parallel tapering transverse bundles on the ventral border. On the left side, muscles do not extend beyond the anterior margin of the gut loop. The prebranchial area is narrow. No perituercular area. The dorsal tubercle is a cushion with a V-shaped opening with one horn turned out. There are 70 branchial tentacles of 3 different orders. The dorsal lamina is ribbed and the ribs project out slightly from the margin. The branchial sac is deeply pleated. The internal longitudinal vessels have small round papillae. There are occasional intermediate branchial papillae between the primary papillae. There are 5-6 oval stigmata in a mesh. The gut occupies three quarters of the left side and is deeply curved. Anterior margin of the gut loop is well above the anterior level of the atrial aperture. The axis of the secondary gut loop passes through the middle of the stomach. Anus has a smooth border and is in level with and directed towards the atrial aperture. Intestine is distended with mud. The gonads are in the gut loop with a branched ovary and the testis follicles spread over the gut loop.

Similar species: The species resembles Ascidia occidentalis Kott, 1985 and Ascidia tuticoriensis in the presence of tentacular fringes on the lobes of apertures and a mesh of muscles on the right side of the body. But it differs from Ascidia occidentalis Kott, 1985 in the presence of the peculiar shape of the body, small papillae on the surface of the test, occasional intermediate branchial papillae, lesser number of stigmata in a mesh and the anal opening posterior to the pole of the gut loop. It differs from Ascidia tuticoriensis in the shape of the body, the position of the apertures and the method of fixation to the substratum.

Synonym (s)

Common Name (s)
Economic Importance and Threats



• Tamil Nadu, Off Tuticorin INDIA (Record: 2005) (Depth: -5 mts)

Literature Source(s)
  • Swami, BS and Chhapgar, BF (2002) Settlement pattern of ascidians in harbour waters of Mumbai, west coast of India Indian Journal of Marine Sciences CSIR 31(3) 207-212 Available at -
  • 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 -

Page last updated on:2009-06-04

Back to Search