First record of feeding by Berthella stellata

January 14, 2010
From: Jeff Goddard

Hi Bill,

A group of us recently traveled to Baja California with Hans Bertsch for a series of low tides. On New Year's Eve at El Tomatal on the Pacific coast we found numerous Berthella strongi and their egg masses on or adjacent to the plakinid sponge, Oscarella, a known prey item for this species (Goddard, 2007)[message #20217]. We also found two specimens of B. stellata, which I had never seen before.

I collected the Berthella stellata and some Oscarella that was growing on a shell, held them separately for one day, and then placed the slugs and the sponge together. Both specimens consumed the sponge overnight. The large pits in the sponge pictured here represent a night's feeding activity by the slug pictured, which had a dorsum 8 mm long. Brenna Green's close-up image is of the same individual.

Locality: El Tomatal, Intertidal, Baja California, Mexico, Pacific Ocean, 31 December 2009, Cobble field. Length: 8 mm. Photographer: Jeff Goddard (top image), Brenna Green (lower image).

Only one species of Oscarella has been described from the Pacific coast of North America (O. carmela from the Monterey Peninsula), and it's not known yet if there are additional species on this coast. Oscarella is thin, delicate, and slimy to the touch, owing to its lack of skeletal elements.

To our knowledge, this is the first record of feeding by Berthella stellata, and brings to seven the number of species of Berthella now known to feed on plakinid sponges.

  • 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,

Goddard, J.H.R., 2010 (Jan 14) First record of feeding by Berthella stellata. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Jeff,

Thanks for this observation. It's great to reach the stage where we can say that a particular genus of slug feeds not just on 'sponges', but specialises on one genus - in this case Plakina. Looking through earlier records on the Forum for B. stellata, I wouldn't be surprised if the sponge in the background of two records [#22041 - from Indian Ocean; #10544 - from Mediterranean] are species of Plakina as well, which would be a nice bit of global confirmation.

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (Jan 14). Comment on First record of feeding by Berthella stellata by Jeff Goddard. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Berthella stellata

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