Could this be a Spanish Dancer?

March 3, 2006
From: Brian Francisco

Hi Bill
Is it possible that these photos are of a juvenille Spanish Dancer [Hexabranchus sanguineus]. This individual was quite small, about 12 mm, and I'm not sure I can count 6 gills.

Locality: Beach, 7 meters, East Timor, Banda Sea, 26 February 2006, Sandy Bottom. Length: 12mm. Photographer: Brian Francisco.

Thanks very much
Brian Francisco

francisco.brian@gmail.com

Francisco, B., 2006 (Mar 3) Could this be a Spanish Dancer?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16000

Dear Brian,
Yes this is indeed a juvenile Hexabranchus. Good call! The gills in juveniles are quite interesting. The dorid nudibranchs are divided into two large groups depending on whether their gills can retract into a protective pocket [Cryptobranchia or Eudoridoidea] or do not have such a pocket  [Phanerobranchia or Anadoridoidea]. Obviously in adults, Hexabranchus has no sign of a gill pocket and each gill is separately inserted into the skin. It would seem to be clearly a phanerobranch. However phanerobranchs are usually the elongate forms, such as the nembrothids,  while the large flat dorids with wide mantle skirts are usually cryptobranchs, with a gill pocket. Cryptobranchs are also sponge feeders, like Hexabranchus, while the phanerobranchs are all specialised feeders on a wide variety of invertebrates. There are of course other anatomical differences.

However if you look at juvenile Hexabranchus, you can see there seems to be a ridge around the gills and the tissue inside that is translucent, without the colour pattern of the rest of the mantle. I wouldn't be surprised if that is all that is left of a gill pocket, which has been lost in the evolution.of this species, but is still indicated in juveniles. Does that make Hexabranchus a very special cryptobranch, or does it suggests that it is a link between the two groups, indicating that the phanerobranchs evolved from the cryptobranchs? I wouldn't like to say.at this stage, but it is certainly something that students of phylogeny should consider. I'm glad you picture shows it so clearly. In living animals they gills can almost completely disappear.
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Mar 3). Comment on Could this be a Spanish Dancer? by Brian Francisco. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16000

Related messages

  1. Chromodoris or Hypselodoris?
    From: Franco De Lorenzi, March 26, 2010
  2. Washed up in north-western Australia
    From: Sean Houlihan, February 23, 2010
  3. Hexabranchus sanguineus from sthn Queensland
    From: Gary Cobb, September 25, 2009
  4. Juvenile Hexabranchus sanguineus from Reunion Island
    From: Sully Bachel, May 8, 2009
  5. Hexabranchus sanguineus from Maui, Hawaii
    From: Chris Ryu, February 11, 2008
  6. The secret life on Hexabranchus sanguineus
    From: David Mullins, December 5, 2007
  7. Hexabranchus sanguineus or Djibouti Giant?
    From: Edward Dixon, September 17, 2007
  8. Feeding Hexabranchus sanguineus from Tofo, Mozambique
    From: Natasja Vandeperre, August 24, 2007
  9. Re: Hexabranchus sanguineus video
    From: Diane Hennelly, August 16, 2007
  10. Hexabranchus sanguineus from Mozambique [2]
    From: Natasja Vandeperre, August 11, 2007
  11. Hexabranchus sanguineus from Mozambique [1]
    From: Natasja Vandeperre, August 11, 2007
  12. Spanish Dancer from Sydney
    From: Donald Miles, July 11, 2007
  13. Re: Nudibranch from the Seychelles, Indian Ocean
    From: Jen Jenny, May 4, 2007
  14. Nudibranch from the Seychelles, Indian Ocean
    From: Jen Jenny, April 27, 2007
  15. Hexabranchus sanguineus from Bali
    From: Asther Lau, April 13, 2007
  16. Hexabranchus behaviour
    From: Sandrine Flodrops, December 4, 2006
  17. Juvenile Hexabranchus from nthn New South Wales
    From: Roxanne Fea, November 8, 2006
  18. Re: Dancing 'Spanish Dancer'
    From: Kamal El Tawil, September 1, 2006
  19. Dancing 'Spanish Dancer'
    From: Joseph De Vroe, August 25, 2006
  20. Hexabranchus sanguineus from Indonesia
    From: Kevin Lee, August 7, 2006
  21. Re: Spanish Dancer Research Paper
    From: Molly Ogden, July 29, 2006
  22. Kissing Hexabranchus sanguineus
    From: Joseph De Vroe, November 8, 2005
  23. Hexabranchus sanguineus with one gill
    From: Joseph De Vroe, November 4, 2005
  24. Mating Hexabranchus sanguineus
    From: R. Grooters & M. Snoek, September 21, 2005
  25. Re: Juvenile Hexabranchus
    From: Colin Ogden, September 3, 2005
  26. Juvenile Hexabranchus strikes again
    From: Colin Ogden, September 2, 2005
  27. Re: Hexabranchus sanguineus from Egypt
    From: Kamal El Tawil, July 11, 2005
  28. Hexabranchus sanguineus from Madagascar
    From: Marco Angelozzi, July 4, 2005
  29. Re: Hexabranchus sanguineus from Egypt
    From: Kamal El Tawil, June 24, 2005
  30. Hexabranchus sanguineus (Spanish dancer) from Egypt
    From: Kamal El Tawil, June 7, 2005
  31. Re: Hexabranchus juvenile from the GBR
    From: Nils Anthes, January 15, 2004
  32. Hexabranchus juvenile from the GBR
    From: Nils Anthes, January 10, 2004
  33. Hexabranchus sanguineus unrolling the mantle
    From: Erwin Koehler, December 16, 2003
  34. Gills on Hexabranchus sanguineus
    From: Gary Cobb, December 11, 2003
  35. Juvenile Hexabranchus
    From: Roberto Sozzani, May 19, 2003
  36. Hexabranchus from Myanmar
    From: Mary Jane Adams, May 2, 2003
  37. Spanish Dancer Research Paper
    From: Molly Ogden, April 29, 2003
  38. Hexabranchus mating photos
    From: Bill Rudman, March 4, 2003
  39. Hexabranchus sanguineus from Lord Howe Island
    From: W.B. Rudman, January 23, 2003
  40. Hexabranchus juvenile from Bali
    From: Danny Van Belle, January 9, 2003
  41. Spanish Dancer - What can we feed it?
    From: Shawn Elston, November 18, 2002
  42. Re: Hexabranchus - its common name
    From: Constantine Mifsud, September 9, 2002
  43. Hexabranchus - its common name
    From: Jason Lewis, September 7, 2002
  44. Size of Hexabranchus
    From: Valeria Safonova, June 22, 2002
  45. Juvenile Hexabranchus sanguineus from Christmas Id
    From: W.B. Rudman, May 10, 2002
  46. Juvenile Hexabranchus sanguineus
    From: Mary Jane Adams, May 9, 2002
  47. Hexabranchus sanguineus from the Red Sea
    From: Marina Poddubetskaia , April 17, 2002
  48. A report on the Spanish Dancer
    From: Student, March 22, 2002
  49. Hexabranchus sanguineus from Bali
    From: Stuart Hutchison, March 21, 2002
  50. Hexabranchus sanguineus - oral tentacles
    From: Stuart Hutchison, March 21, 2002
  51. Are these Spanish Dancers?
    From: Reine, January 27, 2002
  52. Hexabranchus? from South Africa
    From: Allan Connell, December 17, 2001
  53. Spanish Dancer?
    From: Joyce Zwiener, December 14, 2001
  54. Spanish Dancer
    From: Belinda, September 7, 2001
  55. Swimming Hexabranchus from the Red Sea
    From: Luigi Montevecchi, August 28, 2001
  56. Eggs of Hexabranchus sanguineus
    From: Luigi Montevecchi, August 28, 2001
  57. Re: Hexabranchus 'aureomarginatus' in Hawaii
    From: John Hoover, August 3, 2001
  58. Juvenile Hexabranchus from Hawaii
    From: Scott Johnson, July 30, 2001
  59. Hexabranchus 'aureomarginatus' from Hawaii
    From: Scott Johnson, July 30, 2001
  60. Hexabranchus 'pulchellus' from Hawaii
    From: Scott Johnson, July 30, 2001

Show factsheet and all related messages