Re: Photo of a living 'Berthella' sideralis

January 8, 2007
From: Jussi Evertsen

Concerning message #19133:

Hi Bill,
I did identify Erling's specimen [message #19089] as a Berthella  based on material that I have myself of similar looking specimens, but with tissue covering the whole dorsum. I suspected Erling's specimen to be damaged. My ID is based on the descriptions given in Odhner  (1939). In my notes in my field notebook I noted the internal shell visible thorugh the dorsal tissue, and the gills located in a cavity on the sides between the dorsal tissue and the foot.

Here are the photos of the specimen of Berthella that I have from Rundholmen at Bud 20/5 2004, collected at 28 meters depth. The specimen is 20 mm from the head to the end of the tail.

Also I have scanned the illustrations given in Odhner (1939) with lateral illustrations of B. plumula and B. sideralis. I also scanned the shell of B. plumula. In Odhner (1939) it is mentioned that B. plumula has been collected from the the tidal zone. I do not agree that Erling's specimen  is a velutinid, but a damaged Berthella exposing the internal shell, because his specimen is similar to the above given specimens ID'd as Berthella from Odhners descriptions and illustrations.

Locality: Rundholmen, 28 m, Bud, Norwegian west coast, 20 May 2004, rocky bottom, steep slope. Length: 20 mm. Photographer: Petter Schmedling.

  • Odhner, N.H. (1939) Opisthobranchiate Mollusca from the western and northern coasts of Norway. Det Kongelige Norske Videnskabernes Selskabs Skrifter, 1: 1-93.

Jussi

jussi.evertsen@bio.ntnu.no

Evertsen, J., 2007 (Jan 8) Re: Photo of a living 'Berthella' sideralis. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19147

Dear Jussi,
Thanks for these photos. If I had had these with Erling's message I would not have considered to be a pleurobranch. It is clearly a velutinid. In Erling's photo the head tentacles are short and blunt and I was happy to interpret the eye spots as being in the body wall at the base of the tentacles as you might expect in a pleurobranch. Your photos clearly show the long tapering head tentacles and the eyes in little pockets on the base of the tentacle - both characters of what we used to call 'prosobranch' gastropods, but not found in opisthobranchs. More specifically in pleurobranchs, we would expect to find enrolled tentacles, as illustrated in Odhner's sketches, and can be seen in many photos on the Forum of species of Berthella.

Why I asked Erling if he had a photo of the right side of the animal was to see if I could see any sign of the gill which, as illustrated in Odhner's sketches, should be on the right side of the body under the mantle.  Your second photo shows the underside of the body from the left side, so we wouldn't see the gill if it was a pleurobranch. However it is very valuable because it shows a clear channel - above the head - leading down to a large hole [arrowed] behind the left eye. This hole is the inhalent opening into the mantle cavity, through which water enters the mantle cavity which contains the chemosensory osphradium, the gills, anus, kidney and reproductive openings. In velutinids the mantle cavity is situated above the head and anterior body and covered by the shell. In pleurobranchs, this mantle cavity is lost, all that remains of it is the region on the right side of the body where we find the gill, anus and reproductive openings.

You mention differences in shell exposure. In some velutinids the amount of shell visible is very variable because the mantle covering it is quite contractile, much like in many cowry snails. Unfortunately it seems we are yet to see a living Berthella sideralis. It puzzles me that all the preserved specimens of B. sideralis and its Nth American counterpart Gymnotoplax americanus (Verrill, 1885) have the shell greatly exposed, much as in Erling's photo. I have never seen that happen in preserved specimens of other species of Berthella, so perhaps Berthella sideralis does have an exposed shell when alive. The other alternative, that all specimens so far collected have suffered identical damage seems rather unlikely.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Jan 8). Comment on Re: Photo of a living 'Berthella' sideralis by Jussi Evertsen. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19147

Factsheet

Velutinidae - are they sea slugs?

Related messages

  1. Colpodaspis sp ??
    From: Jean Michel Crouzet, April 19, 2010
  2. Lamellaria from Tunisia
    From: Jamila Ben Souissi, January 18, 2010
  3. Unknown seaslug from Whangaparaoa, New Zealand
    From: Graham Bould, August 20, 2009
  4. Shell-less gastropod from Gulf of St Lawrence, Canada
    From: Patrice Goudreau, July 21, 2007
  5. Re: Photo of a living 'Berthella' sideralis
    From: Jussi Evertsen, January 15, 2007
  6. Re: Photo of a living 'Berthella' sideralis
    From: Jeff Goddard, January 5, 2007
  7. Photo of a living 'Berthella' sideralis
    From: Erling Svensen, January 5, 2007
  8. Re: Lamellaria from Turkey
    From: Mehmet Baki Yokes, December 15, 2006
  9. Lamellaria from Turkey
    From: Haluk Akbatur, December 13, 2006
  10. Unknown dorid? from the Red Sea
    From: Neil Horlock, June 16, 2006
  11. Velutinid snail from Japan
    From: Yasuhiro Shamoto, April 6, 2006
  12. Berthella? from Croatia
    From: Mat Vestjens, February 28, 2006
  13. Re: Nudibranch ? from Spain
    From: Juan Lucas Cervera, January 20, 2006
  14. Nudibranch ? from Spain
    From: Marga Iglesias, January 19, 2006
  15. Re: Mysterious sea slug? from Cornwall
    From: Bernard Picton, November 15, 2005
  16. Mysterious sea slug? from Cornwall
    From: Judith Oakley, November 1, 2005
  17. Re: Unidentified Arctic 'Nudibranch'
    From: Philip Sargent, September 15, 2005
  18. Re: Velutinidae in the Arctic
    From: Constantine Mifsud, July 5, 2005
  19. Unidentified Arctic 'Nudibranch'
    From: Tim Siferd, July 1, 2005
  20. Re: Corambe? or velutinid from California
    From: Jeff Goddard, May 19, 2005
  21. Marsenina stearnsii from Oregon
    From: Jeff Goddard, May 19, 2005
  22. Lamellaria diegoensis from Oregon, USA
    From: Jeff Goddard, May 19, 2005
  23. Corambe? or velutinid from California
    From: Douglas Hansen, May 16, 2005
  24. Velutinid from Lord Howe Island
    From: Ian Hutton, February 26, 2004
  25. Berthella? fromNew South Wales
    From: Rachel Przeslawski, September 18, 2003
  26. Sea slug mystery
    From: Steve Zanieri, March 18, 2003
  27. Velutinid from Lord Howe Island
    From: Ian Hutton, December 11, 2002
  28. Is this a velutinid ?
    From: Marina Poddubetskaia, October 28, 2002
  29. Unidentified velutinids from Turkey
    From: Baki Yokes, October 8, 2002
  30. Chelynotus semperi from Solomon Ids
    From: Bruce Potter, September 19, 2002
  31. Velutina? from Alaska
    From: James H. McLean , September 7, 2002
  32. Snail? Slug? from Alaska
    From: Clinton Bauder, August 7, 2002
  33. Re: Opisthobranch? from Mediterranean
    From: Juan Lucas Cervera, July 23, 2002
  34. Opisthobranch? from Mediterranean
    From: Jean-Pierre Bielecki, July 22, 2002
  35. Opisthobranch with a shell
    From: Elianny Dominguez , September 19, 2001
  36. Coriocella spp from the Maldives.
    From: Jim Anderson, May 8, 2001
  37. Mystery from the Maldives
    From: Nishina Masayoshi, January 16, 2001
  38. Velutinid from Port Stephens
    From: Ron Greer, May 28, 2000
  39. Velutinid from southern New South Wales
    From: Akos Lumnitzer, January 27, 2000
  40. Re: Coriocella nigra from Japan
    From: H.Ono, October 6, 1999
  41. Coriocella nigra from Japan
    From: H. Ono, October 5, 1999
  42. Coriocella nigra
    From: Jacquie Sheils , May 5, 1999
  43. A nudibranch-like Coriocella from Okinawa
    From: Bob Bolland, March 23, 1999
  44. Your response to my Coriocella query
    From: Yves Muller, November 2, 1998
  45. Information on Coriocella spp
    From: Yves Muller, October 28, 1998

Show factsheet and all related messages