Chromodoris conchyliata query feeding on sponge

October 7, 2005
From: Colin Ogden

Hi Bill,
This morning on a dive on our Ribbon reef I found this nudi. At first I thought it was Chromodoris conchyliata, but on downloading it I am not convinced.

Locality: Sodwana Bay, South Africa. IndianOcean coast. Depth: 18 metres
Length: 30 mm. 6 October 2005. Coral reef. Photographer: Colin Ogden

The border to its mantle and the colours exposed under its hood next to its mouth are making me question my ID. Also the full colour on its gills does't look right to be the C. conchyliata. I had a look on the Forum at our previous messages and noted that you were keen to see the sponge it was feeding on. It appers to be feeding in the photos, but conditions were rough and it had just drifted into that position. Would it start feeding within seconds of landing next to its food source, or are its actions a system of just trying to stabilise itself.

Ogden C M, 2005 (Oct 7) Chromodoris conchyliata query feeding on sponge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Colin,
I can understand your hesitancy in identifying this as C. conchyliata, but I am sure that's what it is. What it lacks is the thin dark purple network between the pustules on the mantle but that is quite variable. It is nice to get a good photo of the underside of the anterior mantle. We have an earlier photo from Sth Africa from Valda Fraser [#2661] showing the same colour. Some of the other photos on the Forum of the dorsal surface show just a reddish orange bit at the edge. This is one of an interesting group of chromodorids with purple on the anterior underside of the mantle.

When I saw your message I thought - great! Colin's got a feeding record for this species. Don't feel bad, but no it is not feeding. The colony it has landed on is a soft coral not a sponge - and the white rounded bit sticking out the front is the front of the foot. Have a look at the nudibranch head Fact Sheet, and Brian Whorton's message [#14139] which has 3 photos, including two other species with purple undersides, to get an idea of their anatomy. The mouth is right between the two oral tentacles, and that is from where the buccal bulb will extend during feeding. I must say I am in two minds whether the white object we can see in your C. mandapamensis photo [#14931] is the buccal bulb or the front of the foot.

Although its not a feeding record, it is a nice record of a colour variation in this species that we didn't know about.
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Oct 7). Comment on Chromodoris conchyliata query feeding on sponge by Colin Ogden. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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