Dear Debbie,

It's difficult to see much detail, but from the shape of the body and the gills, I suspect this is a chromodorid nudibranch. In the north of New Zealand, warm currents often bring down larvae of quite tropical species. This looks quite like the chromodorid Noumea norba or perhaps its one of the other speices which look very similar [see N. purpurea colour group]. The sponge may be its food, but we would need better photos to identify either the nudibranch or the sponge

Best wishes,
Bill Rudman

Dear Bruce,
That was a lucky find. The gills appear to be half retracted so I suspect they are more like those of D. fumata then D. nigra. However I am not convinced it is that species, as I have never seen one coloured quite like this, or with such a narrow mantle skirt. All I can ask is you keep your eye out for egg masses - they might give us a clue.

Best wishes,
Bill Rudman

Dear Brent,
There is always the possibility that this is a species whch arrived in ballast water, but then again it could just be an example of the the vagaries of the currents carrying larvae up and down the west Australian coastline.

I don't recognise this species but it has the look of a species of Thordisa Perhaps Jamie Chan or Terry Gosliner who have recently published on this genus can give us some clues.

• Chan, J. M. & Gosliner, T.M. (2007) Preliminary Phylogeny of Thordisa (Nudibranchia: Discodorididae) with descriptions of five new species. The Veliger, 48: 284-308. 

Best wishes,
Bill Rudman

Dear Bruce,

It could be D. carneola or Doriopsilla aurea but both of those usually have some white marks or spots, and the mantle is usually thicker and stiffer than you animal appears to be, and I have never seen such a bright yellow form of Dendrodoris nigra. I'm afraid I admit defeat

Best wishes,
Bill Rudman

Dear Bruce,
Sorry I can't help. It certainly doesn't look like any nudibranch I know. I am not even sure what it is. It could be a flattened holothurian, or possibly a flatworm but without a better idea of its anatomy I can't be sure. I know its not always possible, but if I see a mysterious animal I give it a gentle prod and if possible turn it over. Only by doing that can you find the clues which will hopefully give you an idea of what phylum your mystery belongs to. Although many animals can disguise themselves from above, its not often that they can completely hide their tube feet, or parapodia, or foot or whatever it is that tells us what they are

Best wishes,
Bill Rudman

Dear Ian,
I am pretty sure this is a species of Cuthona. The distinctive colour pattern should make this species instantly identifiable, but I can find no described species with this colour pattern. I suspect this is another unnamed species. It deserves a page rather than being hidden on an 'unidentified page' but I will wait a while in case someone recognises it.

Best wishes,
Bill Rudman

Dear Ian,
It certainly is not a species previously reported from New Zealand, but as the Kermadec Islands are probably best considered part of the wider Indo-West Pacific I looked further afield, but have not found a description matching your animal. From its general shape and ceratal arrangement I would say it is most probably a species of Phidiana. The colour pattern, with its distinctive orange lines, and the shape of the rhinophores, with two ridges or brackets, which seem to be notched anteriorly and posteriorly, should make this species instantly identifiable if it has been described.

I'm afraid I can't find it. Perhaps someone else will recognise it. Failing that, I suspect it is an undescribed species.

Best wishes,
Bill Rudman

Dear Mick,
Thanks for another photo. I've had another think about it and still think Dendrodoris elongata is a possibility, but looking at the high rhinophore pockets, which hide most of the rhinophore stalk, made me wonder if it could possibly be a species of Aphelodoris? However there is no way of knowing unless you come across it again. If you do you can poke it a bit and see if it greatly elongates, but failing that try and turn it over and look at its head - not that easy underwater -. If the head has proper tentacles [see dorid head Fact Sheet] then it is not a Dendrodoris and so Aphelodoris becomes a real possibility. Unfortunately I haven't got a head of Dendrodoris in the Forum at present for you to compare, but its head merges with the foot and has no distinct tentacles.
Best wishes,
Bill Rudman

Dear Mick,
I may need some more information on this, if you have it. I am pretty sure it is a species of Dendrodoris as the skin looks quite thin and translucent. The species that comes to mind is Dendrodoris elongata. It is by no means a perfect fit in colour pattern, but the ruffled edge to the mantle suggests it has a lot of 'stretch' available. Did you by chance notice the animal moving? If so, was it able to stretch out like the photos of D. elongata on the Forum?

Dendrodoris albopurpura is also a possibility, but again it stretches out and the black spots are usually on pustules and surrounded by a white ring. Another one with black spots, thin mantle and ruffled edge is D. guttata, but in that species there is an orange-brown background colour.  It is possible your animal is a new species, but it is also possible that it is one of these three species in which the backround colour is absent. My suspicion is that it is D. elongata so if you have any other background information on its movement and whether it can elongate, I would like to hear about it.
Best wishes,
Bill Rudman

Dear Kristin,
I suspect this is a chromodorid of some sort, but I think we would need to look at its anatomy to be sure what genus.There are many white species with orange markings but I don't remember this one. There seems to be a yellowish band at the mantle edge but I am not sure if that is just a trick of the light.
Best wishes,
Bill Rudman

Dear Sue,
This is almost certainly a species of Cuthona, but our present understanding of the group is such that I wouldn't hazard a guess at is identity. As you have found I suspect some species of this group travel around the world on the bottom of yachts like this so it could have come from anywhere.
Best wishes,
Bill Rudman

Dear Ian,
I have to admit defeat with this one. It certainly does not look like any species I am familiar with so I looked through some of the old literature. In the 1800s quite a few species were described from New Zealand on the basis of preserved animals. No information was collected on the colour or shape of the living animals. A number of tuberculate dorids were described but none seem to fit your animal. Without some information on its anatomy I'm afraid I could only make a wild guess as to what genus it belongs to.
Best wishes,
Bill Rudman

Dear Mereana,
I am afraid that identifying marine invertebrates is quite difficult even with a good description or a photo. Unfortunately it is almost impossible for me to solve your puzzle without a photo, especially when you are not sure if it is even a slug.

The only Clown nudibranch I know of is Triopha catalinae and I don't know any NZ relative with the colour pattern you describe. One possibility is Ceratosoma amoena. Another suggestion would be to use the Forum SEARCH BUTTON and type in New Zealand. That will give you a list of the species from New Zealand that are on the Forum. If it has been reporte previously on the Forum from NZ it will make it easier for you to find a photo of it.
Good Luck,
Bill Rudman

Dear Gareth,
This is a species of Doto a group which are not that common in New Zealand and so have not been well studied. Two species have been reported from New Zealand. One of these is apparently a cosmopolitan species, Doto pita and the other has been likened to Doto bella Baba, 1938. However, D. bella, which was described from Japan, is said to have a black patch midway along each rhinophore, whereas your animal has completely black rhinophores, except for a white tip. Your animal is very similar to what is called Doto bella in Suzuki, 2000 from Japan, and Doto racemosa in Marshall & Willan 1999 from Heron Island, but as I mentioned above D. bella has a small black patch midway along the rhinophore, rather than being all black, and no black is described by Risbec for D. racemosa.

I can't be sure what species you have here but the black rhinophores are very distinctive.

Best wishes,
Bill Rudman

Dear Gareth,
This is an intersting find. With such distinctive black oral tentacles, this aeolid should be easy to identify - if it has a name. Is there also a black tip to the 'tail' (posterior end of foot). If you have any other photos of it I might be able to get a few details of other parts of its body. I though at first that it might be a species of Cuthona but it looks like the front of the foot might have tentacle-like extension out each side which would rule that out.

Basically I can't recall a New Zealand or southern Australian species of aeolid with this colour pattern. perhaps someone will recognise it.
Best wishes,
Bill Rudman

Dear John,
Your animal is indeed a gastropterid, probably a species of Siphopteron, but at this moment I am not sure whether it is an undescribed species or a colour variation of one of the tropical species with a similar colour pattern. I have found this species in many parts of southeastern Australia and the colour pattern is quite variable.
Best wishes,
Bill Rudman