Re: Cadlinella subornatissima from Kwajalein Atoll

November 12, 2008
From: Scott Johnson

Concerning message #22007:

Hi Bill,

Thanks for the comments on Cadlinella subornatissima. I'm sure that gray material in the rock crevices is sponge, but I'm afraid I cannot say for sure if the nudibranch was eating it. The particular photo of the animal strongly adhered to the rock with those patches of gray sponge around was indeed shot exactly where the animal was found. After a few minutes exposed to sunlight and camera lights, it got up and moved around. But I also cannot say if this sponge is what I thought was Halisarca metabola, the species I reported as the prey of Cadlinella ornatissima. My notes say only that a specimen was found eating that sponge, but do not say how I made that identification (and alas, my aging memory fails me on that point). I am not very knowledgeable about sponges and most of my id's from Enewetak came from comparisons with identified specimens in the collections of the Mid-Pacific Research Lab. I found Cadlinella ornatissima on a variety of substrates, but almost never could I clearly tell if they were feeding. Attached is one shot of that species that shows it near, but not on, a bit of gray sponge similar to that in the photo of C. subornatissima. It is just one more thing to watch for.

Locality: Kwajalein Atoll, 6 m, Marshall Islands, Pacific, February 1991, Under rock. Length: 15 mm [e047_09a]. Photographer: Scott Johnson.

Scott Johnson

Johnson, S., 2008 (Nov 12) Re: Cadlinella subornatissima from Kwajalein Atoll. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

m2Thanks Scott,

Cadlinella is proving a difficult genus to get any solid information on its food choice. Apart from just wanting to now something about its biology, its apparent basal position in the evolution of the chromodorids means that its food choices could help to better understand how other chromodorids began to become more specialised in their food choice.  We know that in the Actinocyclidae [Actinocyclus, Hallaxa] - which is the possible sister group to the chromodorids - that species feed on the sponge Halisarca, and we know that species of Cadlina feed on Halisarca and darwinellid sponges. As many species of Chromodoris feed exclusively on darwinellids this provides us with a nice link between the Chromodorididae and the Actinocyclidae. So it would be nice to have better evidence for the food of Cadlinella.

Hopefully conversations like this will jog someone's memory of a photo they have or like you, cause them to add it to their 'to do' list. I don't expect miracles, but I am more than happy with a nice surprise every now and then.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Nov 12). Comment on Re: Cadlinella subornatissima from Kwajalein Atoll by Scott Johnson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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