Pattyclaya arena from Guam

April 22, 2006
From: C. Carlson & P-J Hoff

Concerning message #16395:

Here are some examples of Pattyclaya arena (Carlson & Hoff, 1977), to go with the P. brycei note. We think the lamellae are related to subsand habitat and have no idea if there will be enough genetic difference between P. arena and the other Caulerpa feeding Elysia to merit a different genus.

Our last Guam record for the animal was in Nov. '75. The type locality was damaged by a typhoon and later became a jet ski area for a neighboring hotel.

Upper: 27mm long alive. Guam, Cocos Lagoon, reef flat. 1 m. 13 May 1971 Host: Caulerpa racemosa. Middle: 19 mm long alive, showoing open parapodia ; Guam, Cocos Lagoon, Sand Island; 13 Oct 1973. Lower: 25 mm long alive. in situ; Guam, Cocos Lagoon, Sand Island; 13 Oct 1973.  Photographer: Carlson & Hoff.

Clay & Patty-Jo

Carlson, C. & Hoff, PJ, 2006 (Apr 22) Pattyclaya arena from Guam. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Clay & Patty-Jo,
Thanks for photos of your Pattyclaya arena. It is fascinating to see how they sit in the sand. Are the lamellae full of plastids? If so, perhaps it has found another way of solving the problem of too much light in a different way to Plakobranchus ocellatus which also lies just under the sand. I think - with no evidence however- that the coral sand pools that these animals live in is too bright for photosynthesis. I suspect that Plakobranchus cuts down the light intensity to optimum levels for photosynthesis by placing its stolen chloroplasts in longitudinal ridges on the inside of the parapodia where they receive only filtered sunlight. Perhaps in Pattyclaya the same thing is happening but the chloroplasts are in tranverse lamellae rather than longitudinal ridges. Something for someone to investigate.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Apr 22). Comment on Pattyclaya arena from Guam by C. Carlson & P-J Hoff. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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  2. Re: Pattyclaya arena from Guam
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