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Hydractinia echinata

(Fleming, 1828)

Erling Svensen Does anybody know if the Hydractinia echinata also lives on solid rock? I see this hydroid on the hermit crab, but I feel that this picture shows the specie living on rock? Any meenings about that?

Niels Schrieken In the north sea we find H. Echinata on shipwrecks. So I am not surprised that you find it om solid rock.

Message posted on Seasearch Identifications on 14 Apr 2012
Erling Svensen Spidercrab with Hydractinia echinata or Podocoryne carnea? Have you seen this hydroid on crab before?

Andy Horton Not sure if I have. has it been associating with Hermit Crabs?

Neil MacInnes Hoping Dawn sorts her palliata from her carciniopados -is this an Adamsia rather than a sponge? (SW Skye)

Neil MacInnes Its not clear, due to enlargement from the corner of a pic! I didnt touch it and dont think there's shine. Wondered ?suberites sponge before thinking the fringing 'fir' might be fringe of a cloak anemone.

Christian Skauge Looks like Hydractinia echinata to me :-)

George Brown I agree with Christian, Hydractinia means it's a mollusc shell.

Neil MacInnes So Hermit/Snail Fir Hydractinia without any sponge/anemone trimmings seems likeliest-Thanks folks

Message posted on Seasearch Identifications on 27 Feb 2013
Penny Martin

Andy Horton Penny: did you note the difference to the Hermit Crabs below under the title Pugilists ?

David Fenwick Snr Afro snail fur !!!

Andy Horton Commensal hydroids

Andy Horton Hydractinia echinata http://www.marlin.ac.uk/speciesinformation.php?speciesID=3537

Sérgio N. Stampar Amazing Hydractiniidae...

Niels Schrieken This picture was taken on the english part of the Doggerbank at the wreck Inger Nielsen. The nudibranch Cuthona is well known from the English waters, but what caught my attention was the foraging behavior. With at least 40 individuals encircled around a metal tube eating Hydractinia echinata from the left side of the tube and leaving eggstrings behind. I find it awesome to see.

Christian Skauge Fantasic shot! Talk about teamwork :-)

David Kipling Good grief, amazing! How deep was this?

Niels Schrieken It's about 20 meters deep.

George Brown Incredible photograph of fascinating behaviour.

Julia Nunn absilutely wonderful picture

Tony Gilbert Amazing shot, I am still looking for C. nana on Hydractinia, so every hermit crab with "fur" that comes along! Think I just missed a Cuthona nana on this hermit specimen, as it seems that its had a reverse-mohican "haircut" down the centr... http://www.flickr.com/photos/tonyjgilbert-images/7501686530/in/set-72157630420768730

Christian Skauge How about a picture like that, with two C. nana's mating on top of the hermit...?

Niels Schrieken Yes Christian that is where I am always looking for when I see hermitcrab. But I have never thought to see a tube with nana eating hydractina like this.

David Kipling Am I right in thinking we should be calling Cuthona now Trinchesia?

Niels Schrieken In the world register of marine species cuthona nana is the correct scientific name: http://www.marinespecies.org/aphia.php?p=taxdetails&id=141627

David Kipling There's a thread on one of the other nudi forums about changing all the Cuthonas to Trinchesia. I personally think we should stop doing that, and move to colour and shape-based names, be much easier to identify them! "Mr Yellow Clubby" is far easier to remember than Limacia clavigera, for example ...

Christian Skauge Problem is, there are lots of different "common names" depending on where you are - latin is the only thing keeping the whole thing together... As for Cuthona to Trinchesia - I have no idea whats right.

Niels Schrieken The other way around if I may believe WoRMS. Example Trinchesia anulata -> Cuthona anulata: http://www.marinespecies.org/aphia.php?p=taxdetails&id=534077

David Kipling There's a long thread on the NUDIBRANCH LOVERS group entitled "Trinchesia instead of Cuthona". I think C nana is actually the sole species allowed to still be called Cuthona!

Christian Skauge DNA matching will eventually save the day :)

Jim Anderson The abstract from Michael Miller's paper in the Journal of Natural Histopry Vol 38 Issue 9, 2004 says in closing. "Re-examination of the local Cuthona species led to a re-assessment of several other tergipedid genera based on the arrangement of the digestive ducts. As a result the genus Cuthona Alder and Hancock, 1855 is restricted to one species, C. nana (Alder and Hancock, 1842), and the genus Trinchesia von Ihering, 1879 re-introduced for the rest of the species previously included in Cuthona." Histopry Vol 38 Issue 9, 2004.

João Pedro Silva I'd really love to hear/read Bernard Picton's view on this.

Message posted on NE Atlantic Nudibranchs on 05 Jul 2012
Eunice Khoo What is this snail covered in? Night dive, Tulamben, 10m.

Penn Dls Looks like that's part of it's mantle?

Eunice Khoo You think so? I'm not sure... looks like lots of "bits"! What's the ID of the snail then?

Blogie Robillo Those are papillae, projections from its mantle that help it breathe, among other things. Not sure about the ID yet though...

Gena Kokonas That is so awesome!!! Great find.

Arne Kuilman In the Netherlands it's called Hydractinia echinata. They're hydroid polyps. These are also food for nudibranchs and we find them on the shells of hermitcrabs.

Eunice Khoo I think that's it, snail fur! Thanks Arne

Arne Kuilman In Norway they call it Club headed hydroid (Clava multicornis)

Rudolf Svensen Anybody knows this one? Image captured South in Norway on a dive today. I guess it was maybe 10 mm long.

Terry Griffiths Cumanotus beaumonti i think would be a good starting point.

Floor Driessen Could this be Cuthona nana? (It feeds on Hydractinia echinata) http://www.habitas.org.uk/marinelife/species.asp?item=W14710

Rudolf Svensen I do not the mout/head looks like Cumanotus beaumonti so I guess it is closer to Cuthona nana.

Peter H van Bragt Considering size and number of cerata C. nana comes very close. C. beaumonti has cerata in front of the rinophores and there seems to be too many cerata for a juvenile C. concinna or C. gymnota.

Christian Skauge Cuthona nana would be my guess too :-)

Message posted on NE Atlantic Nudibranchs on 17 Jun 2012
Animalia (Kingdom)
  Cnidaria (Phylum)
    Hydrozoa (Class)
      Hydroidolina (Subclass)
        Anthoathecata (Order)
          Filifera (Suborder)
            Hydractiniidae (Family)
              Hydractinia (Genus)
                Hydractinia echinata (Species)
Associated Species