February 12, 2001
From: Bernard Picton
I just read your comment on Trapania goslineri:
Thanks for the photo. What are species of Trapania doing on sponges? One wish I have for the new year is that someone shows me conclusive evidence that they feed on sponges, or if not some evidence of what they do feed on. For that matter, the same hold true for species of Siphopteron and other gastropterids.
Bill Rudman. "
So here's your wish! - in situ photographs of Trapania pallida - Isla Onza, Galicia, Spain -July 1978. (Sorry about the poor quality - first time using a new Nikonos/flash combination I think, overexposed and unsharp. I searched for them last night and finally found them in a box in the garage where they'd been for the last four years so they're a bit fungusy! They weren't really useable but the scanner did get something off them.)
Now in my experience, Trapanias are as rare as hens teeth, but at this time and in this area they were all over the place in great gaggles! (Two species - see next email). They weren't eating the sponges but were cutting clear areas through the Entoprocts which were themselves overgrowing the sponges.
Picton, B., 2001 (Feb 12) The food of Trapania pallida !!. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3767
Thanks very much for these observations and for the information on feeding in Trapania tartanella - a very interesting find.
For those of you not familiar with the Entoprocta, they are a small phylum of sessile aquatic animals with a ring of tentacles which make them look superficially like hydroids. However, unlike hydroids, they have a gut that loops around with both a mouth and an anus which both open in the ring of tentacles. They are stalked, and some are solitary animals and others live as part of colonies, joined much like hydroids, by a root-like system of stolons. For a long time they were considered to be Bryozoans but are now considered a distinct and unrelated phylum. Because of this some people feel we should use the word 'Ectoprocta' for the stream-lined phylum Bryozoa [minus the Entoprocta] but this is proving almost as confusing as continuing to us Bryozoa. To add to the confusion the names 'Kamptozoa' and 'Calyssozoa' have been suggested to replace the 'Entoprocta'.
Bill Rudman.Rudman, W.B., 2001 (Feb 12). Comment on The food of Trapania pallida !! by Bernard Picton . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3767