Egg-laying Cuthona sibogae from Port Stephens

August 6, 2008
From: Leanne & David Atkinson

Dear Bill,
We found these eggs on a colony of the orange hydroid Sertularella quadridens, which had lots of Cuthona sibogae in it. We have never seen another nudibranch in this hydroid and these look like nudibranch eggs. We know you can't make a positive identification unless you actually see them laying the eggs but it would seem that these may be their eggs. Their eggs aren't mentioned in the fact sheet and there doesn't seem to be any other messages re their eggs. Have Cuthona sibogae eggs been observed before? We'll keep trying to catch them in the act of laying.

Locality: Fly Point, Port Stephens - Great Lakes Marine Park, Port Stephens, 12 metres, New South Wales, Australia, Pacific, 24 May 2008, Scattered sponges, hydroids, ascidians and soft corals on a sandy bottom. Length: Approximately 30 mm. Photographer: Leanne & David Atkinson.

Best wishes,
Leanne & David Atkinson

atk@hunterlink.net.au

Atkinson, L. & D., 2008 (Aug 6) Egg-laying Cuthona sibogae from Port Stephens. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21761

Dear Leanne & David,

Thanks for the photos of the egg masses. You are right to be cautious, but I tend to agree with your strong suspicions that these are the eggs of Cuthona sibogae. I added a close-uup alongside showing a section of the hydroiod to show the fully extended polyps on which this aeolid feeds. In this species the polyps each have their own case [theca] into which the polyp can withdraw. Some hydroids, like Tubularia and its relatives don't have such cases and are known as athecate hydroids. In identifying thecate hydroids, obvious characters such as whether the stalks branch or not, and the nature of the branching, are used, but also the arrangement of the individual theca - are they arrangement opposite each other along each branch, or are they arranged alternately etc, etc. That's why it is very difficult for an expert to identify hydroid species from photos, unless the close-ups show the  stalks and the thecae very clearly. Even with such photos, I am afraid hydroid specialists are not that common.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Aug 6). Comment on Egg-laying Cuthona sibogae from Port Stephens by Leanne & David Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21761

Factsheet

Cuthona sibogae

Related messages

  1. Cuthona sibogae from Indian Ocean (Mayotte Island)
    From: Sandrine et Hugues Flodrops, March 18, 2009
  2. Cuthona sibogae from Thailand, feeding
    From: Marcel Tanke, February 10, 2009
  3. Mating Cuthona sibogae
    From: Leanne & David Atkinson, August 5, 2008
  4. Mating Cuthona sibogae
    From: Patricia Dilworth, August 28, 2007
  5. Cuthona sibogae from Sulawesi
    From: Mike Krampf, April 18, 2007
  6. Unidentified nudibranch from Mabul
    From: David Kearnes, March 3, 2006
  7. Are Phestilla sibogae & Cuthona sibogae different?
    From: Xikun Song, August 17, 2005
  8. Cuthona sibogae on the Sunshine Coast
    From: Gary Cobb, October 20, 2003
  9. Cuthona sibogae - diseased?
    From: Leanne & David Atkinson, September 3, 2003
  10. Cuthona sibogae from Port Stephens
    From: David & Leanne Atkinson, February 7, 2003
  11. Cuthona sibogae from Riau, Indonesia
    From: Alice Lee, November 4, 2002
  12. Cuthona sibogae? from eastern Australia
    From: David Harasti, October 29, 2002
  13. Re: Flabellina? from the Red Sea
    From: Erwin Koehler, October 26, 2002
  14. Re: Flabellina? from the Red Sea
    From: Philip Cromwell, October 26, 2002
  15. Flabellina? from the Red Sea
    From: Erwin Koehler, October 24, 2002
  16. Cuthona sibogae from Papua New Guinea
    From: Erwin Koehler, October 23, 2002
  17. Flabellina? identification
    From: Alice Lee, March 26, 2002
  18. Cuthona sibogae from Port Stephens
    From: Akos Lumnitzer, March 18, 2002
  19. Cuthona sibogae from the Marshall Islands
    From: Scott Johnson, June 18, 2001
  20. Cuthona sibogae from Mozambique
    From: Kirsty Miller, June 11, 2001
  21. Food of Cuthona sibogae
    From: Richard Willan, September 17, 2000
  22. Re: aeolid from Fiji
    From: Bruce Wight, September 15, 2000
  23. aeolid from Fiji
    From: Bruce Wight, September 13, 2000
  24. Cuthona? from Sth Africa
    From: Valda Fraser, December 13, 1999
  25. Cuthona from Port Stephens, New South Wales
    From: Ron Greer, December 13, 1999

Show factsheet and all related messages