Didemnum vexillum

Paula Lightfoot Can anyone tell me what this is? Hopefully not Didemnum vexillum - it didn't really look like a squirt, couldn't see any zooids.

David Kipling Can't see any zooids either ... but is it out of the water and the siphons contracted?!? Hopefully a sponge!

Cynthia D. Trowbridge I was thinking sponge as well...though I always use touch to confirm

Rob Spray Dawn says: Oscarella ?

David Kipling OK Dawn, good call! http://www.marlin.ac.uk/speciesinformation.php?speciesID=3988#

Paula Lightfoot Thanks Dawn! That looks and sounds just like it - firm but gelatinous, velvety texture etc...

Becky Hitchin def not D vex :)

Wilfried Bay-Nouailhat Hi, in November 2011, the surface of several colonies of Didemnum (Didemnum vexillum? Rade de Brest, 3 meters) was pierced with numerous holes containing very small eggs. Colonial ascidians are often preyed by gastropods, but do you have any idea of the species that did that?

Rudolf Svensen Anybody knows this one? Image captured South-West in Norway.

Erling Svensen Yes. Please tell me the name. I will buy you a Guiness....

Rudolf Svensen It's quite common, so strange nobody knows the name? It is not Didemnum vexillum, thats for sure.

Erling Svensen No, and it is not Ciona as well. But Bjørn will go on pension in spring next year and we will then start to find out what this one and some other strange species are.

David Kipling It's a very pretty polyclinid ... almost like lots of little Clavellinas in a colony. We must get a name for this! And very Christmassy as well ;)

Tony Gilbert I think this is the leathery sea squirt invasive species Didemnum vexillum. The source material I used (images from CCW on NNSS website) point strongly to it, and not similar native UK species - that are shown on Habitas / Bernard Picton . As with these types of IDs it is always best to seek several opinions before submitting a record! This was not found near any harbours or areas like this. It was located along a reef some 30m away from the wreck of the Thesis in the Sound of Mull. If it is the invasive species, then perhaps it's come from divers or from the numerous ferries and other craft that ply the waters perhaps?

Becky Hitchin D. vex is actually the carpet sea squirt, Styela clava is the leathery one ;) But ... to me that doesn't look like D. vex, but I'm more used to seeing it above water.

Becky Hitchin oops. to continue! There don't seem to be the water channels that characterise Dv, and the colour looks sort of wrong, though we're realising how variable the colour can be. The best way to really tell would be to get a sample and send it to John Bishop or Rohan Holt.

Tony Gilbert Apologies, meant carpet. Tricky to get hold of physical sample now unless I return to Mull :-) but thanks anyway.

Becky Hitchin :P I don't *think* it's D. vex, more maybe another Didemnum species. But saying that, D. vex is proving rather variable among outbreaks. Rohan Holt, what do you think?

Rob Spray Overdue short edit of the dive around the oyster raft to check out the site before the survey... lots of weed and squirts!

Pamela Stephens Facebook This is just a message to say how very nice it was to see you both on Dawn's birthday. I was wrong about the broadcast in the morning - the comic thing was part of woman's hour. It was just by accident I chose this e-mail of yours to reply to. I wanted to report that we signed a petition about the protection of some of the Suffolk coast to be presented next year. I have doubts about my computer skills so I won't write too much. Love M xxx

Jens Christensen Hi Rob. Interesting construction, and video. How long has it been sitting in the water, and what camera did You use for this video?

Jens Christensen Seems to be a lot of Sargassum muticum on the mooring of the construction. Is it as abundant on the Seefloor?

Rob Spray I'd guess this raft was 5+ years old but may be recovered for maintenance annually so its true age might be hard to establish. This was filmed using a Canon HF200 HD camcorder. The seafloor can be seen in the part 2 and 3 videos. Some sargassum down there but not very much.

David Kipling Very squirty, as you say! Floating man-made structures seem perfect for them - clean surface for planktonic larvae to settle on, little by way of predation being raised up off the seabed (although I notice a crab or two had swum onto it!), and being designed for oysters presumably stuck somewhere with a nice gentle current to keep them fed. Loads of Styela clava. At about 4 min in there is a good shot of a colonial ascidian (I assume, unless it's a dripping sponge of some form) with a rather worryingly pendulous growth habit. What is it? It reminds me of the pictures of Didemnum vexillum I've seen (eeek!). http://www.marlin.ac.uk/PDF/Aliens_2.pdf

David Kipling Indeed - so what does Rohan Holt think it is?

Rob Spray a Diplosoma... no full guess :-(

Paula Lightfoot Why are there no records of Didemnum vexillum on the NBN Gateway? It was added to the Marine Recorder species dictionary in January 2010. I thought when the latest Seasearch dataset was added there might be some records, but still nothing! Becky Hitchin, Liz Morris don't you have any records?

Becky Hitchin Not diving records, no, and our Shoresearch records haven't made it to NBN recently. It's on of those ongoing "we've got to do this!" jobs. I wonder if we could make up a subtidal / intertidal record set for D. vex around the UK? Paula, would that be possible somehow?

Paula Lightfoot That would be possible and sounds useful! The records should go to DASSH if they haven't already. What other organisations besides Kent Wildlife Trust do you think would have records of this lovely species?

Becky Hitchin Never seen a squirt quite so wrinkled before ...

Julia Nunn where was this? looks rather like Didemnum vexillum?

Becky Hitchin I don't think it's D. vex, it doesn't look right closer to. Defnitely didemnid-y though. It was on a sewage pipe on Worthing beach, Sussex. Just a very strange looking beast.