Ascidia challengeri   Herdman,  1882 (Sea Squirt)
Organism information awaits expert curation
Class: Ascidiacea

Image copyrights: The Marine Biological Association of India

Size: 3.5 cm long, 1.8 cm broad.

The body is more or less egg shaped, with a rounded posterior end. The anterior end narrows to a short conical branchial siphon without ridges and the atrial siphon is inconspicuous, situated one third the distance from the anterior end on the dorsal surface. Attachment is by the posterior end of the left side. There are 8 branchial and 6 atrial lobes with ocelli between them. No tentacular fringes. The test is firm, cartilaginous and translucent. Test vessels branch profusely and end blindly without an ampulla. The species can be easily identified by its external appearance, nature of siphons, numerous branchial tentacles, shallow pleats in the branchial sac, long stigmata and a mud distended gut.

The body wall is thin and delicate. There are circular muscles around the siphons and an irregular meshwork of muscles on the right side, which straighten into a band of parallel, transverse muscles across the mid dorsal line and ventral margin. On the left side muscles are present only anterior to the gut loop. Branchial tentacles crowded and of two orders. About 80 long tentacles could be counted. The prebranchial area is narrow. No peritubular area. The dorsal tubercle is an oval cushion with a V-shaped opening. Dorsal ganglion a short distance posterior to the dorsal tubercle. Dorsal lamina is a ribbed membrane with the ribs projecting beyond the edge of the membrane and double anteriorly. Branchial sac has shallow pleats. The meshes are long with 6 stigmata in a mesh. Branchial papillae are rounded or triangular. Intermediate branchial papillae very rare. Gut loop is deeply curved. Oesophagus is short. The stomach elongated with a few faint longitudinal striations. Primary gut loop is open at the open. The rectum is short and closely associated with the descending limb of the intestine. The intestine is distended with mud. The axis of the gut loop passes near the pyloric end of the stomach. The anus is smooth and lies below the level of the gut loop. Gonads are in the usual position. The proximal end of the ovary has many short branches. The testis follicles lie spread over the mesial surface of the gut loop.

Synonym (s)
Phallusia charcoti (Sluiter, 1905)
(New combination)
Phallusia challengeri (Herdman, 1882)
(New combination)
Ascidia dispar Arnback, 1938
(Original combination)
Ascidia charcoti Sluiter, 1905
(Original combination)

Common Name (s)
Economic Importance and Threats



• Tamil Nadu, Tuticorin INDIA (Depth: -(4-5) mts)

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 -
  • 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:2010-08-16

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