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Laomedea longissima

(Pallas, 1766)


René Weterings Are these "Eubranchus rupium"? Found in Lake Grevelingen, The Netherlands, yesterday evening. Watertemperature was 0 degrees Celsius.......!

Brendan Oonk Yes E.rupium "Noordelijke knuppelslak"

Pascal Van Acker mooi zoekwerk

René Weterings Pure luck!

René Weterings For the dutch divers some info to find them: Dit paartje heb ik gevonden op de meest westelijke staander van de steiger bij Dreischor Reefballs. De uiterste staander dus aan de kant van de aluminium trap. Ze zaten aan de westzijde van pilaar, halverwege. Mocht iemand interesse hebben om ze te gaan bekijken, dan weet je ongeveer waar je ze kunt vinden.

Mick Otten Dank voor de tip!

Bernard Picton The cerata are unusually swollen, but I see the green digestive gland in the body. I'm not certain of that identification, though, but I've not seen this species alive myself.

Brendan Oonk I agree cerata are somewhat swollen, but what else could it be? I know of no other Eubranchus with blue-ish white tops of the cerata and with the green zigzag line (digestive gland) showing on its body.

Bernard Picton The one thing I've learned is never to assume something is the nearest thing. If it has some differences then it could easily be an undescribed species.

Jørn Ari http://www.nudibranchia.dk/eubranchus-rupium-aeolid.html

Tony Gilbert I'd agree with that synopsis Bernard - have fallen down that pit plenty of times!

Arne Kuilman I am going to search for them tomorrow!

Tony Gilbert Ah, the joys of Grevelingen Meer and its reef balls! I know it usually has a higher-salinity, because of the sluijs, so can it actually get down to a temperature of 0C? Perhaps at a certain depth then. Last time I dived it it was 12C (June) to about 12m, then around 5-8C at 24m in darkness passed the reef balls and to a platform.

Marco Faasse Tony Gilbert, the Grevelingenmeer is almost stagnant, indeed with stratification in winter and summer. Because of this, and because of little exchange with the North Sea, surface water temp in winter can get as low as 0 (or minus 1?) degrees C, and in summer once 26 degrees has been measured! Certain species, such as dead man's fingers, you won't find in the upper 12 m in the Grevelingenmeer.

René Weterings Last sunday the water was 0 degrees Celsius up to 10m depth!!

Marco Faasse I suppose the thermocline is just above the zone where dead man's fingers occur. Everything above the thermocline I consider as surface water; 0 degrees C. at 10m seems perfectly credible to me.

René Weterings Tony...is it that hard to believe that it can get this cold?

Tony Gilbert Rene, I was just wondering about the physics of it, salinity, density of water etc. They don't open the gates often, prob. unheard of these days I guess.

René Weterings The gates are almost always open, since a few years, because of the problems with oxigen in the deeper parts of this lake. Hence the high salinity that is almost as high as the North Sea. These extreme cold periodes are rare in the Netherlands. In februari 2012 part of the lake was even frozen and the watertemperature was -1 degree Celsius.

Arne Kuilman I've dived at the same spot and found the nudibranch (thanks René). My Suunto registered 1C and I had a wetsuit. Too much surge to get a good closeup. The photographer in front of me used pegs to weight the laomedea down and get a clear shot of the nudi's. Interesting idea, but I usually don't handle animals.

Arne Kuilman I heard from a different divers ten's of these can be found in a couple of weeks at St. Annaland if people want to search them elsewhere as well. They eat Laomedea longissima and Obelia sp.

Message posted on NE Atlantic Nudibranchs on 28 Jan 2013
Taxonomy
Animalia (Kingdom)
  Cnidaria (Phylum)
    Hydrozoa (Class)
      Hydroidolina (Subclass)
        Leptothecata (Order)
          Proboscoida (Suborder)
            Campanulariidae (Family)
              Laomedea (Genus)
                Laomedea longissima (Species)
Associated Species