Sponge prey of Berthella from the NE Pacific

July 20, 2007
From: Jeff Goddard

Hi Bill,

Here are some images of Berthella strongi feeding on the plakinid sponge Oscarella carmela, plus one image taken by Dr. Stewart Schultz last summer of O. carmela from Cape Arago, Oregon. Last year I found four individuals of B. strongi on this sponge near Santa Barbara and was able to document feeding by all four on the sponge in the lab. Last summer I also had an opportunity to test whether two B. californica from Cape Arago, Oregon would prey on Oscarella carmela or the superficially similar Halisarca sacra from the same locality. Both individuals consumed only the Oscarella.

Locality: Ellwood boulder field, Low intertidal, California, USA, Pacific Ocean, 7 October 2006, Rocky shore. Length: 5 mm. Photographer: Jeff Goddard.

Prey records are now available for six species of Berthella from around the world. All feed on plakinid sponges, suggesting that Berthella specialize on this family of sponges. Recent evidence indicates that plakinid homoscleromorph sponges are more closely related to the Eumetazoa than to other sponges, so they have been getting some fairly widespread attention.

I document these new prey records for Berthella in a paper just published in The Veliger, and before too long hope to investigate the diet of B. ilisima, the large and conspicuous species from the more southerly Panamic biogeographic province.

• Goddard, J.H.R. (2007) Berthella (Opisthobranchia: Pleurobranchidae) from the Northeast Pacific Ocean Prey on Plakinid Sponges (Homoscleromorpha: Plakinidae). The Veliger 49 (2): 97-100.

Best wishes,
Jeff

goddard@lifesci.ucsb.edu

Dear Jeff,
Thanks for keeping us up to date with your research. As we learn more about feeding in the opisthobranchs it appears that there are very few generalists. I won't be surprised - if I last long enough - if most species turn out to be highly specialised feeders retricting their food to a very few species.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Jul 20). Comment on Sponge prey of Berthella from the NE Pacific by Jeff Goddard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20217

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