Didemnum maculosum

Louise Allcock Didemnum maculosum

Jon Chamberlain David Kipling / Bernard Picton - could you name the crusty squirt? or should we record them as that for now (as I didn't sample it)? http://www.flickr.com/photos/underwaterinferno/8072327402/in/set-72157631733973528/ Beadnell Point, Northumberland 7m rock wall

David Kipling I'm largely guessing at D maculosum as you suggest, but ....

Jon Chamberlain Is the crusty squirt in the middle Molgula sp?

David Kipling Most likely, from what I understand. There are probably loads of Molgula species in the UK, largely indistinguishable based on external appearance.

Colin Munro It actually looks rather soft and gelatinouus in the picture (do you know if it was?). If so might be a Diplosoma.

Jon Chamberlain The squirt in question is the single, crusty one in the mid-upper-left of the picture. Most the picture is taken up with what I assume is Didemnum maculosum. I didn't poke the crusty one but others that looked similar (and did get poked) retracted the siphons but not the body which was quite solid and crusty.

Erling Svensen ..... and this one..... (look post below).....

Wilfried Bay-Nouailhat We have a similar form that I think is Didemnum maculosum.

Erling Svensen After prof. Bjørn Gulliksen has been her, we have photographed this one and then look in the microscope, Bjørn sayes this is D. helgolandicum. So now I am quite happy :-)

Wilfried Bay-Nouailhat Yes, but F. Lafargue who accepted this species in 1968, reexamined the type specimen of D. helgolandicum described by Michaelsen and then considered it (D. heloglandicum) as a synonymous of D. maculosum cf. révision Taxonomique des Didemnidae des côtes de France, 2eme partie, 1976.

Erling Svensen I do not know, Wilfried. Bjørn uses his "bible" book for identification, but I will ask him about this later. He is on his way back to Oslo now and I will be on the plane soon for Wales in UK. Thanks for the information.

Wilfried Bay-Nouailhat Lafargue wrote a paper about it in 1972, the abstract gives a lot of information. http://link.springer.com/article/10.1007%2FBF01616312

Richard Yorke After some post processing

Richard Yorke I hope Dylan Jones does not mind me playing with his picture, but does this make the ID easier

David Kipling Still looks like a sponge to me - Didemnids are usually 'clean' and not encrusted with epibionts, and don't have long sticky-outy bits. I'd say sponge either with silt-encrusted spikules or else it's covered with some spiky epibiont. What's your thought Richard?

Richard Yorke Posting more pics

Dylan Jones Fiddle away to your heart's content Richard.

Liz Morris Now confirmed as Didemnum maculosum by the squirt xperts. :)

Penny Martin pachymatisma johnstonia??

Bernard Picton It's a Didemnid, Didemnum maculosum perhaps, though I doubt if what we call D.maculosum is really all a single species. Didemnids are the most difficult sea squirts to identify, and often look like sponges.

Bernard Picton Perhaps Didemnum coriaceum if that's a valid species... http://www.habitas.org.uk/marinelife/species.asp?item=ZD860

Penny Martin Thank you for your help .... sorry I am so dim .... I am seeing loads but don't find it easy to ID ... is there a good book on sea squirts and sponges ??

Paula Young Help, help? Any ideas? This was taken a couple of miles west of Dover, about 18m. Initial thought was a squirt of some sort (comments from Mr Kipling, Becky Hitchin welcome).....possibly Didemnum maculosum...but I'm not entirely convinced and am just not that good with blobby masses??

David Kipling Looks like star shaped holes, so squirt with closed siphons would be good start. But in the back some look to be raising themselves up a little, and actually I can't see inside any of the holes. I've been caught withnthi

David Kipling ... With this one before with and intertidal "squirt".

Paula Young Another thought - There were lots of Alcyonium d. around, and I did come across one earlier in the dive with nearly all the polyps retracted (got over excited and thought it was some interesting nudi at first, but no...). I just thought maybe this looked a bit too bumpy or irregular to be Alcyonium?

Becky Hitchin one or two of the polyps do look like they have 8-fold symmetry. but that's squinting very hard and hoping

Paula Young What's DMF...apart from something I can do a kitchen makeover with? Oh no...hang on!

David Kipling Alcyonidium digitatum, the finger dead man's finger ;)

David Kipling No I was making word play on finger bryozoan (Alcyonidium diaphanum versus Alcyonium digitatum).

Paula Young I think DMF it is then...there were loads around! Thanks all!

Marco Faasse Another one I'm not sure of: is this Didemnum maculosum? The spikes aren't always there? (Pointe de Trévignon, southern Brittany, May 2013)

Wilfried Bay-Nouailhat Yes, this tiny form of D. maculosum is frequent at Pointe de Trévignon !

Marco Faasse Thanks Wilfried!

David Kipling Is this the "var dentate" version Wilfried?

Wilfried Bay-Nouailhat Yes, David, it is the easiest form of D. maculosum to identify

Bernard Picton I'm sure Didemnum maculosum will turn out to be an aggregate species. We used to call this one "small white spiky" back in the 1980's and it does not grow up into anything like the coloured forms, but stays small, probably by dividing.

Ronaldo Ruy Hello, this looks like D. apersum which differs D. maculosum through larva with three adhesive papillae, it's correct?

Wilfried Bay-Nouailhat yes, D. maculosum larva has two adhesive papillae. D. apersum is a species living in Tokyo Bay, isn't it?

Ronaldo Ruy Thank you! Yes, but I just have seen some similar colonies that were collected in the Pacific Islands - specifically in French Polynesia - that don't are larvae, but I'm thinking that this is D. apersum... Thanks again Wilfried!

Marco Faasse Another one I'm not sure of: is this Didemnum maculosum? The spikes aren't always there? (Pointe de Trévignon, southern Brittany, May 2013)

Wilfried Bay-Nouailhat Yes, this tiny form of D. maculosum is frequent at Pointe de Trévignon !

Marco Faasse Thanks Wilfried!

David Kipling Is this the "var dentate" version Wilfried?

Wilfried Bay-Nouailhat Yes, David, it is the easiest form of D. maculosum to identify

Bernard Picton I'm sure Didemnum maculosum will turn out to be an aggregate species. We used to call this one "small white spiky" back in the 1980's and it does not grow up into anything like the coloured forms, but stays small, probably by dividing.

Ronaldo Ruy Hello, this looks like D. apersum which differs D. maculosum through larva with three adhesive papillae, it's correct?

Wilfried Bay-Nouailhat yes, D. maculosum larva has two adhesive papillae. D. apersum is a species living in Tokyo Bay, isn't it?

Ronaldo Ruy Thank you! Yes, but I just have seen some similar colonies that were collected in the Pacific Islands - specifically in French Polynesia - that don't are larvae, but I'm thinking that this is D. apersum... Thanks again Wilfried!