Food of Berthella plumula

January 5, 2002
From: Bernard Picton

Hi Bill,
To accompany my photos of Berthella plumula here us some feeding information.

It seems to feed on the sponge we call Oscarella lobularis (actually the Oscarella in the British Isles is probably a new species, distinct from the Mediterranean O. lobularis). The
appearance of Berthella seems to be providing camouflage on Oscarella, with a central transparent patch mimicking an oscule of the sponge and the
reticulate pattern looking similar to lobules of the sponge. Thompson (1984)
suggests that Berthella plumula may feed on tunicates so I was interested to
see on the Forum that Berthella ocellata feeds on Plakina, as this is quite closely related to Oscarella.

The upper photo is of the sponge Oscarella lobularis - Blasket Is., Co. Kerry. The lower photo is of a group of Berthella from St. Kilda, Scotland, July, 1984.


Picton, B.E., 2002 (Jan 5) Food of Berthella plumula. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Bernard,
Bill Rudman

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