Thuridilla from Ningaloo Reef, Western Australia

January 18, 2006
From: Adrian Baddeley

This looks like Thuridilla indopacifica although the colour pattern seems closer to T. moebii.

Locality: Mandu Mandu Wall, Ningaloo Reef, Western Australia. Indian Ocean. Depth: 10 metres. Length: 10 mm. 16 April 2004. Coral reef wall
Photographer: Adrian Baddeley

Individuals seen on two consecutive dives at Ningaloo Reef in April 2004. Found at 10 metres depth on gentle slope at base of a coral wall, 100 metres from shore, on ocean side of wall.

Adrian Baddeley

Baddeley, A., 2006 (Jan 18) Thuridilla from Ningaloo Reef, Western Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Adrian,
This is T. moebii. I think we still have quite a lot to learn about colour variation in this group. Some apparently change colour depending on their physiological state, which is one form of colour variation, and then there is the genetic variability we find within a species. The limits to both these forms of variation do not seem to be clear as yet in many species. At present we can say the white spotted region on the parapodial edge and on the tips of the rhinophores are good characters of T. moebii. Also the way the background colour of the parapodial edge changes from orange to a dark blackish brown is not found in other species.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jan 18). Comment on Thuridilla from Ningaloo Reef, Western Australia by Adrian Baddeley. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Thuridilla moebii

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