Onchidium from the Arabian Sea

November 16, 2006
From: Bhavik Patel

Dear Dr.Bill,
I am working in Bombay Natural History Society (Mumbai) on Marine Mollusca. I last week had been in Vealver (Dist. Junaghad, State. Gujarat, India) which is situated on the coast of Arabian Sea. There I found Sea Slugs thousands in numbers, and many of them were mating. But next day when I went there again for the collection of a few samples, the numbers were only in 100 or 200. Unfortunately I didn't recognise the species. so please help me on this.

Locality: Velaver, Above water level (10-20 cm.), Gujarat, Arabian Sea, 6 November 2006, Rocky Shore with lots of sea weeds. Length: 7-12 cm. Photographer: Bhavik Patel

Bhavik Patel
Project Officer.
Conservation Department.


Patel, B.K., 2006 (Nov 16) Onchidium from the Arabian Sea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18362

Dear Bhavik,
This is a marine pulmonate of the family Onchidiidae. It is definitely a slug, but its closest relatives are the land slugs not the sea slugs. In the photo alongside you can see a pair of head tentacles, each with a small black eye at the tip. Opisthobranchs don't have stalked eyes like this. I suspect your animal is Onchidium verruculatum, which is a large onchidiid from the Indian Ocean. When it is immersed in water branched gill-like papillae extend from the tubercles on its back and look very much like a nudibranch's gills

The animals you saw may have been mating, but the white structure in your photo alongside is the 'snout' which bears the mouth at its tip. Have a look at the Fact Sheet and attached messages for further information on this group of slugs.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Nov 16). Comment on Onchidium from the Arabian Sea by Bhavik Patel. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18362

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