Cuthona cocoachroma
Williams & Gosliner, 1979

Family: Tergipedidae


Knnown from Pacific coast of Nth America [Washington to California].


Middle Cove, Cape Arago, Oregon, USA., June 1984. on hydroid prey, Thuiaria sp. Photo: Jeff Goddard.

This delicate aeolid is known from Duxbury Reef, just north of San Francisco (Williams & Gosliner, 1979) to the Olympic Pennisula, Washington (Goddard, et al., 1997). It reaches nearly 20 mm in length and can be recognized by its white-frosted cephalic tentacles and long rhinophores, white tipped cerata lacking spots, and chocoalate brown cerata cores. Cuthona cocoachroma specializes on a single species of Thuiaria and preys on this thecate hydroid by using its radula to rasp through the outer covering of the hydroid, and then sucking out the soft inner tissues (Goddard et al., 1997; Goddard, 1998; unpublished observations). Cuthona cocoachroma lays white, cord-shaped egg masses on Thuiaria sp. and like its sympatric congeners, hatches as planktotrophic veliger larvae with inflated egg-shaped shells (Goddard, 1991).

• Goddard, J.H.R. (1991) Unusually large polar bodies in an aeolid nudibranch: a novel mechanism for producing extra-embryonic yolk reserves. Journal of Molluscan Studies 57(4, supplement): 143-152.
• Goddard, J.H.R. (1998) A summary of the prey of nudibranch molluscs from Cape Arago, Oregon. Opisthobranch Newsletter 24: 11-14.
• Goddard, J.H.R., Wayne, T.A. & Wayne, K.R. (1997) Opisthobranch mollusks and the pulmonate limpet Trimusculus reticulates (Sowerby, 1835) from the outer Washington coast. The Veliger 40: 292-297.
• Williams, G.C. & Gosliner, T.M. (1979) Two new species of nudibranchiate mollusks from the west coast of North America, with a revision of the family Cuthonidae. Zoological Journal of the Linnean Society 67: 203-223.

Authorship details
Goddard, J.H.R., 2003 (January 20) Cuthona cocoachroma Williams & Gosliner, 1979. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Cuthona cocochroma or C. concinna

September 24, 2007
From: Mark Lloyd

Clinton Bauder indicated to me that this species did not have that many pictures of it and I should upload the one I have. This was also taken on the same trip in the Port Hardy area of British Columbia. Is this Cuthona cocochroma or C. concinna

Locality: Hussar Point, Vancouver Island, 15 M, British Columbia, Canada, 26 August 2007, Wall ledge. Length: 15mm. Photographer: Mark Lloyd.

Mark Lloyd

Lloyd, M., 2007 (Sep 24) Cuthona cocochroma or C. concinna. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Hi Mark,

The correct identification of some of the Cuthona species is difficult on external features alone. These two species are perfect examples.

For the purpose of putting a name on your animal, I will say that I believe this is what Terry Gosliner intended to be Cuthona cocochroma. I base this identification on the deep dark brown ceratal cores of your specimen and the white pigment on the dorsal surface of the oral tentacles and the distal half of the rhinophores.

Nice photo, thanks,
Dave Behrens

Behrens, D.W., 2007 (Sep 24). Comment on Cuthona cocochroma or C. concinna by Mark Lloyd. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Cuthona cocoachroma from Oregon

January 24, 2003
From: Jeff Goddard

Hi Bill,
Here is an account of Cuthona cocoachroma for the Forum. The photograph is of the aeolid on its hydroid prey, Thuiaria sp. and was taken in the lab using specimens collected from Middle Cove, Cape Arago, Oregon in June 1984.

Best wishes,

Goddard, J., 2003 (Jan 24) Cuthona cocoachroma from Oregon. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Jeff,
Bill Rudman