Dear Dom,

I think these photos clarify the situation quite well. Although from the right side of the animal the eggs do seem to be coiled in an ribbon-like tube, the photo from the left side shows the eggs scattered more randomly. So I think we can say that their apparent arrangement in a coiled egg ribbon is just an illusion. To further explain the position of the ovotestis - which makes the eggs and sperm - have a look at your photos in an earlier message [# 22088]. The dark brown-black organ which fills the back half of the body is the digestive gland, which is unique to molluscs, and as its name suggests, is involved with digesting the food, absorbing the nutrients into the bloodstream, and in excreting the waste products. In most dorids the ovotestis forms a layer over the top half of the digestive gland and in some cases, such as Trapania, also extends into a lump behind the digestive gland. We can see this very clearly in your two photos.

Best wishes,
Bill Rudman

Dear Dom.,

We haven't that much information on the eggs of Trapania, but the photo we have of the egg mass of T. benni [message #5992] suggest the white spots in your photo could be egg-sized, and the way they are arranged certainly looks like the egg-ribbon after it is deposited. However the ovo-testis - where the eggs and sperm are produced forms a thin layer over the digestive gland just where the white spots are in your photo. Usually the eggs travel down to the female genital opening in a single string and are fertilised on the way. They are not surrounded in the mucous jelly and arranged into the tubular cluster of eggs until they are about to be deposited. Either your animal is doing something very strange or what we can see is just an illusion. Perhaps what we can see are the eggs in the ovotestis and the apparent clear lines between them, which give the impression we are looking at a coiled tube of eggs, are blood vessels in the ovotestis.

Its an interesting photo. Any other interpretations would be welcome

Best wishes,
Bill Rudman

Dear Dom,

Now you have seen the size to look for I am sure you will spot them without glasses. However if you are lucky and the kamptozoa are more plentiful, a sure sign is a 'furry' covering over the sponge. Bernard Picton's photos [message #3767] show it very well. Another good indication in many cases are the little brown spots which can be seem in the photo on the kamptozoa Fact Sheet.

Best wishes,
Bill Rudman

Dear Lucas,
Thanks for letting us know. I was pretty sure there was a recent paper on feeding in T. maculata but I have just converted by bibilographic database to a new program and am still having a few 'teething problems'.

For those of you unfamiliar with the paper, Luis and Lucas report both T. maculata and T. hispalensis feeding on a kamptozoan of the genus Loxosomella which was living on sponges of the genera Dysidea and Sarcostragus.

Best wishes,
Bill Rudman

Dear Dom,
As I have discussed elsewhere on the Forum, species of Trapania were for a long time considered to be sponge feeders, because they were usually found on certain sponges. However if we look at their radular teeth, we find that they are quite different from the teeth of other sponge feeders. We now have good evidence from photographs on the Forum that many species of Trapania feed on species of kamptozoa [entoprocts] which grow on these sponges. I have looked carefully at your photos and found two kamptozoan animals in the bottom right corner of one. I have included a close-up. Also, in the photo alongside my comments, I can see a 'furry' covering over the right edge of the sponge colony. I wouldn't be surprised if that was an aggregation of kamptozoans as well. This is the first direct evidence on the Forum of T. maculata associating with kamptozoans.

You can sometimes see one or two black spots inside the body of the kamptozoan individuals. These spots are the waste products inside the gut of the kamptozoans - in fact it is often the only clue I can see in photos that the blurry cover over some sponges is in fact kamptozoans. Concerning the black mass in the Trapania, that is the colour of the nudibranch's digestive gland. In most molluscs it is a dark brown to black colour. The digestive gland is a unique molluscan organ which produces digestive enzymes, absorbs and digests food, and excretes wastes.

As to whether any species of Trapania eats sponge. My personal feeling is that I am sure they don't, but since we don't have evidence for all species all I can say is that there is no direct evidence that they do and a lot to say they feed on kamptozoans that live on sponges. The more we investigate, the more evidence is accumulating to show that nudibranchs are often very specialised feeders, some species feeding on only one food species. It also appears that in most cases, food choice is linked to phylogenetic relationships - that is closely related species will eat the same or similar food items. We find similar food specialisation in many invertebrate groups. For example, the caterpillar larvae of many butterflies and moths will only feed on only one or two species of plants.

Best wishes,
Bill Rudman

Dear Haluk,
The violet nudibranch is most probably Flabellina pedata, and as you say its cerata have either been autotomised or damaged in some way. However the orange-spotted animal is not to blame. This is Trapania maculata which belongs to a group of nudibranchs that feed on entoprocts, small stalked animals, which previously used to be mistaken for bryozoans.
Best wishes,
Bill Rudman

Thanks Marina,
Bill Rudman

Dear Baki,
It certainly looks like Trapania maculata. Interesting to see it on a sponge colony - Ircinia sp. perhaps? - which is one of its usual habitats. As you will see elsewhere on the Forum, these animals feed on entoprocts.

I am not sure if this species has been recorded this far east in the Mediterranean before. Hopefully our colleagues can let me know whether this, and your other contributions, are new records for the northeastern Mediterranean.
Best wishes,
Bill Rudman

Dear Bernard,
I must admit I gave up when I realised it was a replacement name, but since Trapania is based on Drepania I guess we are allowed to say it also originates from the Greek 'drepane'. Thanks for an elegant solution to an old puzzle.
Cheers,
Bill Rudman

Dear Miquel,
Thanks for the photos. It is certainly nice to find something for the first time. Concerning the origin of the word Trapania. The name was introduced by Pruvot-Fol (June, 1931) as a replacement name for Drepania Lafont, 1874 which was already in use for an insect. By strange coincidence Macfarland published another replacement name (Drepanida) only a month later.

When I was in Sicily for the Menfi Workshop I wondered whether the Sicilian town of Trapani was the origin of the name Trapania, but I could find no connection. The type species of Drepania, and its replacment names, is Trapania fusca. It was originally found at Arcachon in France, so if there is a connection with Sicily I would be interested in hearing of it. Unfortunately Pruvot-Fol does not give a reason for the new name Trapania so I can only assume it was made up to sound similar to Drepania.

• Rudman, W.B. (1987) The genus Trapania (Nudibranchia: Goniodorididae) in the Indo-West Pacific. Journal of Molluscan Studies, 53: 189-212.

Best wishes,
Bill Rudman

Dear Bernard,
Thanks for the photo. It's nice to have one of Tom's photos on the Forum. I often think that if he was still around he would have embraced the world wide web with his abundant enthusiasm. All the Forum needs now is some more of the many species of Trapania reported from the Mediterranean and adjacent waters,
Best wishes,
Bill Rudman