Re: Feeding of Sagaminopteron ornatum

April 24, 2007
From: Ayumi Murakami

Concerning message #11470:

Dear Bill
I would like to report on a facinating sight in regards to Sagaminopteron ornatum.

Locality: Zamami Island, 15m, Kerama Is, Okinawa, Japan, Pacific Ocean, 7th April 2007, coral reef. Length: 8mm. Photographer: Mitsuo & Ayumi Murakami.

They attached themselves underneath the dead coral to feed. The most interesting thing is that there seems to be an extended mouth in purple sponge in the close up picture. Perhaps they are feeding?

I hope these pictures are useful for your research.

Ayumi Murakami

Ayumi M, 2007 (Apr 24) Re: Feeding of Sagaminopteron ornatum. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Ayumi,

Thanks for these interesting photos. Your reference to Jason Bell's message [#11470] is interesting because he suggested they might be feeding on the tube fan worms in his photos. Certainly your middle photo seems to show the mouth region expanded over the sponge but I can't see any damage to the sponge. Interestingly, in the other two photos the animals seem to be lifting the edge of the sponge colony up as though they are interested in something other than the sponge.

Which brings me back to Jason's tube worms. If you look carefully at your photos, there are qite a few clusters, and single worm tubes present, some growing in the middle of the sponge colony. I have put a ring around some on the lower photo. I can't be certain, but I think polychaete worms may prove to be their preferred food.

I know it is difficult doing delicate things underwater, but a useful thing to do when you find something apparently feeding like this, is to gently lift it off 'its food' and see what it is actually doing. In this case you may have found its mouth was holding on to a worm tube, or if it is a sponge feeder, you would have seen a damaged part of the colony.

Thanks for this intersting observation. Hopefully it will encourage others to join the hunt for the food of the gastropterids.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Apr 24). Comment on Re: Feeding of Sagaminopteron ornatum by Ayumi Murakami. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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