Sea slug from Tioman Island, Malaysia

February 16, 2004
From: Andrew Lee

Hi! I collected this sea slug, which I can't identify and was hoping for your expertise. I picked it up from Tioman Island, Malaysia, which is within the Indo-Pacific range. It is quite small in size, slightly less than 2 inches in length. Unfortunately, I can't send a picture now. However, here is the description: its body resembles that of sea slugs from the family Phyllidiidae, and is a mottled army green/brown(the colour of live rock which it was camouflaged with) with a very indistinct grey stripe on its back. The texture of its body is quite like Ricordea mushroom corals with little bumps all over. Some bumps are very prominent with a yellow coloration on the tip. I found it during low tide, clinging to a piece of rock. I think it is an intertidal species as the habitat which it is from is fully submerged during high tide, and completely exposed during low tide. The sand is quite soft and very fine, kind of like silt, and salinity quite low, at about 1.018SG, as it was near the mouth of a stream that flowed into the sea. Andrew Lee

Lee, A., 2004 (Feb 16) Sea slug from Tioman Island, Malaysia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Andrew,
This is indeed a 'slug', and it is found in or near the sea but it is not an opisthobranch sea slug. It is in fact an onchidiid, which are a group of marine pulmonates closely related to land snails. They have a lung-like cavity which allows then to breath both in air and in water. From memory, I think a group in Singapore discovered they had about 10 species living there. They had good anatomical differences, but could only be separated externally on small colour differences.
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Feb 16). Comment on Sea slug from Tioman Island, Malaysia by Andrew Lee. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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