Pink Dirona albolineata from Vancouver Island

July 7, 2006
From: Minette Layne


I found this pink Dirona albolineata crawling on kelp in a tide pool on Vancouver Island. I observed two rather interesting things when looking at this individual, and I'm hoping that someone on the forum will have more information about these two things.

First, when I gently coaxed the slug from the kelp into my observation bowl, it emitted some sort of white, milky substance into the water. It quickly dispersed and I was unable to get a picture of it. I assume this was some sort of defense mechanism, but I can't find reference to this behavior in the places I've looked.

Second, it had a round protuberance on the dorsum that I have not seen before. Although you cannot clearly tell this from the pictures, the round "thing" moved in the current as the cerata did, but it didn't seem to have the same white line as the cerata, and it definitely did not have the pointed shape that the cerata do. Do you have any idea what the round thing is?

Thank you very much for any information you can provide. And thank you for this terrific forum. I've learned a great deal here.

Locality: Point-No-Point, near Sooke, on Vancouver Island, Intertidal, British Columbia, Canada, Pacific Ocean, June 25, 2006, In kelp bed. Length: 8 cm. Photographer: Minette Layne.

Sincerely,
Minette Layne

minette_layne@hotmail.com

Layne, M.C., 2006 (Jul 7) Pink Dirona albolineata from Vancouver Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16991

Hi Minette,

Good to hear from you again.  Beautiful specimen, but obviously one that has been disturbed in the past, evidenced by the regenerating cerata on each side of the head.  This is a clear example of autotomy, a reflex reaction where body parts are dropped to confuse an unwanted intruder.

The white substance you observed was likely a defence chemical as you suggest, however little if anything is known about this kind of a defensive strategy in this family.  Certainly all other suborders of Nudibranchs secrete defensive chemicals.  At the moment I am at a loss to think of an Arminacean that does.

The round projection you refer to (see Bill's circle on the close-up, above) is the anal papilla, which in this genus is located dorso-medially prior to the last cerata.  This anatomical feature is similar in location to the anus found in the dorid nudibranchs, but differs from the lateral location of the anus in aeolids and dendronotids.

Thanks for sharing this,
Dave Behrens

Behrens, D.W., 2006 (Jul 7). Comment on Pink Dirona albolineata from Vancouver Island by Minette Layne. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16991

Factsheet

Dirona albolineata

Related messages

  1. Re: Dirona albolineata & D. pellucida interaction
    From: Jackie Hildering, April 8, 2010
  2. Dirona albolineata & D. pellucida interaction
    From: Jackie Hildering, April 8, 2010
  3. Re: Dirona albolineata mating and spawning
    From: Jacqui Engel & Jackie Hildering, April 6, 2010
  4. Re: Dirona albolineata eggs?
    From: Jackie Hildering & Glen Miller, August 26, 2009
  5. Infested Dirona albolineata from British Columbia
    From: Marli Wakeling, November 25, 2008
  6. Feeding of Dirona albolineata
    From: Jackie Hildering & Glen Miller, March 17, 2008
  7. Re: Parasites on Dirona albolineata
    From: J. Hildering & G. Miller, November 12, 2007
  8. Dirona albolineata mating and spawning
    From: Marcos Perreau Guimaraes, September 10, 2007
  9. Re: Colour variation in Dirona albolineata
    From: Dave Washburn, August 24, 2007
  10. Mating pair of Dirona albolineata
    From: Daniel Hershman, June 5, 2007
  11. Unknown White Nudibranch..looks like an angel!
    From: Sandy Grummon, December 8, 2006
  12. Dirona from British Columbia
    From: Avery Bartels, May 20, 2006
  13. Colour variation in Dirona albolineata
    From: Dave Behrens, April 28, 2006
  14. Colour phases of Dirona albolineata
    From: Jan Kocian, April 28, 2006
  15. Dirona albolineata and Melibe leonina
    From: Jackie Hildering and Glen Miller, July 15, 2004
  16. Dirona albolineata from British Columbia
    From: Bruce Wight, October 24, 2003
  17. Dirona albolineata from Carmel, California
    From: Clinton Bauder, July 19, 2003
  18. Dirona albolineata from Canada
    From: Linda Penny, May 30, 2002
  19. Colour variation in Dirona albolineata
    From: Marli Wakeling, December 19, 2000
  20. Colour variations of Dirona albolineata
    From: Marli Wakeling, October 22, 2000
  21. Variation in Dirona albolineata
    From: Marli Wakeling, September 24, 2000
  22. Information on Dirona albolineata
    From: Jeff Goddard, June 17, 2000

Show factsheet and all related messages