Umbraculum umbraculum feeding

March 25, 2006
From: Leanne & David Atkinson

Dear Bill,
You asked for some photos of Umbraculum umbraculum feeding. We thought these were feeding. When we find them they are frequently on these orange barrel sponges both at Fly Point and Halifax sponge gardens. They blend in well with the texture and colour of the sponge. We see them less frequently at The Pipeline where there are fewer orange barrel sponges.

They often end up, we presume, eating a hole into the sponge and become buried in the hole, which makes it difficult to see if they are actually feeding. Attached is a photo of one buried in a sponge. We've also included a long shot to show more of the structure of the sponge.

Locality: Fly Point Marine Reserve Port Stephens, 14 metres, New South Wales, Australia, Pacific, 31st January 2004, Sandy bottom many sponges soft corals ascidians and bryozoans. Length: 120 - 200 mm. Photographer: Leanne & David Atkinson.

Leanne & David Atkinson

Atkinson, L. & D., 2006 (Mar 25) Umbraculum umbraculum feeding. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Leanne & David,
Thanks for these interesting photos. I am not sure of the identity of your sponge, but in New Zealand they feed on a variety of spiculate sponges such as Aaptos, Tethya and Ancorina. The white material at the edge of the sponge 'wound' looks interesting. It looks like the skeletal stucture of spongin and siliceous spicules which hold the sponge body together. I don't knonw if this means Umbraculum has regurgitated this or what. My understanding was that the slug bit or scraped off chunks of sponge and swallowed them undigested. I certainly have seen its faecal pellets which consist mainly of nicely arranged bundles of sponge spicules, showing that it certainly eats some sponge material whole.

If you have any clues where the white material comes from I would be interested
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Mar 25). Comment on Umbraculum umbraculum feeding by Leanne & David Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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