Thanks Michael,
The size of the eggs (see inset) would suggest that this species has planktonic larvae.
Bill Rudman.

Note added March 31, 2001: Yoshi Hirano has just alerted Mike and I that the egg ribbon image was reversed. It is now the right way around. The animal is of course photographed from the left side so the genital opening, from which the egg ribbon is being extruded, is not visible. ...... Bill Rudman.

Thanks Drew,
These animals are the same colour pattern as in your earlier message, supporting my feeling that this is a northwestern Australian colour form - though photos proving me wrong are very welcome. The egg ribbon photos are also very interesting. I have been asking for egg ribbon photos in the hope that there might be some obvious differences in colour or shape to correlate with body colour. However looking through the Forum messages I think 3 colour forms have this yellow coloured egg mass. Which only goes to prove that there is seldom a simple answer.
Best wishes and many thanks,
Bill Rudman

Dear Kristin,
If you have a look through the other messages on the Hypselodoris bullocki pages you will see that others have asked the same question and I am afraid the answer is not very palatable. Firstly aquarium shop owners who are telling their customers that nudibranchs are grazing herbivores are either lying or just don't know. In either case I think they are irresponsible and not exercising their duty of care to their customers, or for that matter to the animals in their care. Imagine the outcry if they started selling puppies and kittens and advised their customers that they just eat cheap bird seed!

Every species of nudibranch has a very specialised diet. No generic 'nudibranch food' exists. In the case of Hypselodoris bullocki we are not even sure which species of sponge it feeds on, but it is basically a specialised sponge feeder and will eat a sponge found in its Indo-West Pacific Ocean home. I am sure the aquarium dealer does not have the sponge in stock, and like most sponges, even if you could identify its food, it would be very difficult to keep alive in a home aquarium. Sorry I can't give you better news, but as I have said to others before I think you should let the aquarium shopkeeper know that keeping and selling nudibranchs, or any animals for that matter, which he has no knowledge of and no ability to keep them alive is unacceptable.
Best wishes,
Bill Rudman

Dear Cindy,
You are not the cause of them dying. Blame that on the people who organised to ship them to the USA then conned shop owners into stocking them and customers into buying them.

There is a slight chance that you have a sponge in your tank that Hypselodoris will feed on. I don't think there is much point taking it back to the shop because they won't be able to feed it either - although it might teach then that they shouldn't be stocking them. As to the eggs. The eggs will hatch as little veliger larvae that will swim in the water looking for planktonic algae to eat. If they escape your filters, and find the right algae to eat they might survive, but unless you have the right sponge, there is little chance they will take the next step and metamorphose into a baby slug.

Sorry I haven't better news for you
Best wishes,
Bill Rudman

Dear Edward,
Thanks for the interesting information. When I began reading your message I found it difficult to believe they would eat breadcrumb sponges or sea anemones but Aplysilla glacialis makes much more sense. From memory I think A. glacialis is endemic to the west coast of North America, so can I assume you are adding this to your aquarium?

Interestingly, Aplysilla glacialis has been reported often as the food of a number of Nth America West Coast species of Cadlina,a genus closely related to Hypselodoris. Although nudibranchs are very specific feeders, there is always a possibility that a closely related sponge from some other part of the world will be acceptable to them. That is why I have suggested in the past that people look for local sponges related to Aplysilla, which is a genus of sponges often eaten by chromodorids, and test them on their captive chromodorids.

Good luck with your H. bullocki
Best wishes,
Bill Rudman.

Dear Drew,
This is one of a group of animals which I am calling at present Hypselodoris bullocki. This colour form is quite common in northwestern Australia from Darwin around to Exmouth. If you look at the other messages about Hypselodoris bullocki you will see plenty of photos showing the various colour variations. I have included a close-up photo of the mating pair.

Neville Coleman has indeed called this the 'Exmouth Chromodoris' but I personally don't like authors making up 'common' names for animals. Firstly they are not names in 'common use' and often different authors will make up their own 'common names' which is very confusing for interested amateurs. A perfect example is found with fish. The fishing industry and fish scientists have spent many years and much effort in trying to prepare a standard list of common names to be used in Australia. Often the same common name has ben used in different parts of Australia for different fish. Ironically if they had just used the scientific names there would have been no confusion and everyone on the world would know what they mean. I think most amateur naturalists are quite capable of using scientific names. After all gardeners do it all the time when discussing plants. This is a rather long-winded way of saying that 'Exmouth Chromodoris' is a bit unfortunate because the species is a Hypselodoris not a member of the genus Chromodoris. If you are going to use a scientific genus name as part of the common name why not just use the scientific name?

Thanks for the beautiful photo, and another record of this colour form.

Best wishes,
Bill Rudman.

Dear Patrick,
If you look through the other messages on this page and on Page 1, you will see others have asked the same question. I don't know of anyone having success with an artificial food. Chromodorid nudibranchs eat sponges by rasping off bits of sponge with their radula. I would think that any artificial food would need to be in a solid block so that the slugs could imitate their normal feeding action. I don't know what 'Angel Formula' is but if it a powder or flakes I can't see how the slug could eat it.

It would certainly be interesting to find some artificial food that actually worked, but my only fear would be that if such a food was found then no nudibranch would be safe from the activities of commercial collectors.
Best wishes,
Bill Rudman.

Thanks Stuart,
Bill Rudman.

Dear Santos,
Many popular books put this species in the genus Chromodoris. One advantage of the Forum is that it can you up to date with what the 'experts' are thinking about such things. One thing I am sure after looking at its anatomy is that it not a Chromodoris. It has features of both Hypselodoris and Risbecia and at present Hypselodoris seems the best place to put it, until a more extensive review can be done on it in all its colour forms.

As to what it feeds on, have a look at all the messages in the Forum on H. bullocki. It has been discussed at some length. There are no easy answer but at least you will get a feel for the problems. To find the messages, some a below your message on this page and some are on H. bullocki Page 1. another way to find stuff on H. bullocki is to use the SEARCH button at the top of each page, or in the yellow band at the top of each message.

Best wishes,
Bill Rudman.

Dear Matthew,
Congratulations on the reconstruction. I would suspect it is part of the Hypselodoris bullocki complex. I am hesitant to say they are all varieties of one species, but must admit to difficulties in finding any anatomical differences. I have not actually seen a 'form' with a blue border, but I do illustrate one from Darwin (Photo D. on the Hypselodoris bullocki page) which has a bluish-purple border.

Best wishes,
Bill Rudman.

Dear Richard,
Since you put Hypselodoris bullocki in the title can I assume that is what you have? Have a look at the photos on the Hypselodoris bullocki Pages to make sure.

If you do have H. bullocki, have a look at the two messages from Laura Romin [message 1, message 2] where we discuss its food and she suggests an artificial substitute. I haven't heard back from her to see if it was a success but it's worth a try or perhaps you could email her.

Have a look at the page and messages about Keeping slugs in captivity.

Best wishes,
Bill Rudman.

Dear Ken,
I am indeed interested in your scan of this blue animal. More records of particular colour patterns are useful in getting an idea of how constant certain colour forms/ species are.

Other photos of other nudibranchs would be equally welcome.
Best wishes,
Bill Rudman.

Dear Scott,
Concerning regional colour forms, the pink form with a pale or white border is the common Great Barrier Reef form and around the North West coast of Australia there seems to be a purple-edged form but more information from others would certainly be interesting.
Best wishes,
Bill Rudman.