Mating Thuridilla gracilis from nthn Mariana Islands

January 30, 2007
From: Yuji Fujie


Dear Dr.Bill,
Here we have three pictures from maybe mating Thuridilla gracilis. They were spinning in the same place. This animal is very common in Saipan but I haven't seen them doing this behaviour before.

Locality: LauLau Beach, 6m, Saipan, Northern Mariana Islands, Pacific Ocean, 21 January 2007, on the dead coral. Length: 20mm. Photographer: Yuji Fujie.

Would you tell us what is the part inside circle, please ?
Best regards,
Yuji

dswith@isletwind.com

Yuji Fujie, 2007 (Jan 30) Mating Thuridilla gracilis from nthn Mariana Islands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19315

Dear Yuji,

Firstly this colour form is what some people would call Thuridilla bayeri [see message #3077]. I am pretty sure that the whitish lump on the right side, at the base of the rhinophore, which you have ringed, is the penis. Two elysiids twisted around each other like this - as you say 'spinning' - is almost ceratinly a mating or copulatory behaviour. In the photo alongside, both animals are wrapped around each other with their penises everted. I am not sure in the photo if the animals are trying to insert their penises into their partner's genital opening or whether they are trying to inject the sperm into the partner's body cavity. Quite a few sacoglossans practice hypodermis insemination in which sperm is transferred, not via the vagina but directly throught the body wall. Hopefully Kathe Jensen will be able to give us her opinion

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Jan 30). Comment on Mating Thuridilla gracilis from nthn Mariana Islands by Yuji Fujie. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19315

Factsheet

Thuridilla gracilis

Related messages

  1. Thuridilla gracilis from S. E. Queensland
    From: David Mullins, May 14, 2010
  2. Re: The foot of Thuridilla bayeri
    From: John Fraser, May 14, 2010
  3. Thuridilla gracilis from Lembeh, Indonesia.
    From: Brian Mayes, March 4, 2009
  4. Thuridilla bayeri ? from Bangka Island, Indonesia
    From: Francois Zylberman, October 13, 2008
  5. Re: The foot of Thuridilla bayeri
    From: Clay Carlson, December 3, 2007
  6. The foot of Thuridilla bayeri
    From: Clay Carlson, November 30, 2007
  7. Possible colour variant of Thuridilla gracilis
    From: Heidi Hösel, October 16, 2007
  8. Thuridilla gracilis from West Papua
    From: Wendy Atkinson, June 5, 2007
  9. Sea grass hitch hiker
    From: Charles Raabe, July 4, 2006
  10. Thuridilla gracilis from Thailand
    From: Nararongpon Sittithaweepat, September 29, 2005
  11. Thuridilla from Mombasa, Kenya
    From: Valérie Besnard, May 18, 2005
  12. Thuridilla gracilis from Singapore
    From: Lim Han Peng, April 28, 2005
  13. Thuridilla bayeri? found in tank
    From: Marc, February 14, 2004
  14. Thuridilla from the Philippines
    From: Erwin Koehler, February 11, 2002
  15. Thuridilla bayeri ? from the Seychelles
    From: Erwin Koehler, June 18, 2001
  16. Re: Thuridilla gracilis from the Solomon Ids
    From: Kathe R. Jensen, June 16, 2001
  17. Thuridilla gracilis from the Solomon Ids
    From: Bruce Potter, June 15, 2001
  18. Thuridilla gracilis from Coral Sea
    From: Des Paroz, October 29, 2000
  19. Thuridilla bayeri & T. gracilis
    From: C. Carlson & P.J. Hoff, September 28, 2000
  20. Thuridilla from coral rock
    From: Andrew Trevor-Jones, September 24, 2000
  21. Thuridilla gracilis from Great Barrier Reef
    From: Stuart Hutchison, August 12, 2000

Show factsheet and all related messages