Re: Elysia diomedea feeding requirements

June 7, 2001
From: Cynthia Trowbridge

Dear Bill and Sean,

Hi. I read with interest your messages about Elysia diomedea. Last year I pulled together all the known records of NE Pacific sacoglossans for publication in The Veliger (Trowbridge, in press); thus, I may be able to shed some light on this species. However, I do need to add that I have never seen the species myself (it is a warm-water species).

The only reported diets of Elysia diomedea are the brown alga Padina and perhaps the red alga Spyridia. When I came across the report (Bertsch & Smith, 1973), I was rather surprised because, like you, I had expected green algae. But, there is little way of mistaking Padina with green algae, and the researchers who reported this surprising diet are well regarded professionally.

Another issue is that Trench et al. (1969) reported that the slug has functional chloroplast retention. I am not sure if functional kleptoplasty has ever been demonstrated with slugs that eat brown algae but there is at least one case with a sacoglossan that eats red algae. So, I think perhaps Elysia may eat more than one alga; I predict that it eats some green algae as well as the taxa listed. My prediction is based on the color of the slugs, namely bright green like green algal chloroplasts. Brown and red algae have accessory pigments in their chloroplasts so do not look bright green (except when the algae are nutrient-stressed or desiccation stressed).

If anyone sees the slug on green algae, it would be great to have that information. I would be happy to identify the algal genus from a digital image if anyone has a photo available. Thank you for considering my comments. Sorry, Sean, that I could not be of more assistance.

• Bertsch, H. & A.A. Smith. 1973. Observations on three opisthobranchs (Mollusca: Gastropoda) of the La Paz area, Baja California, Mexico. Southwestern Naturalist, 18: 165-176.
• Trench, R.K., R.W. Greene & B.G. Bystrom. 1969. Chloroplasts as functional organelles in animal tissues. Journal of Cell Biology, 42:404-417.
• Trowbridge, C. D. 2000 or 2001. Northeastern Pacific Sacoglossan Opisthobranchs: Natural History Review, Bibliography, and Prospectus. The Veliger (in press).


Trowbridge, C., 2001 (Jun 7) Re: Elysia diomedea feeding requirements. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Cynthia,
Thanks for your interesting comments. I must admit I am surprised that Padina is considered a food source. Concerning sacoglossans utilising non-green plastids, you may recall a message I posted about Brian Brandley's work showing that Elysia cf. furvacauda changes its food algae 3 times during its life cycle and in two instances at least it utilising different plastids (green & red).

As Cynthia says, any observations gratefully received
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Jun 7). Comment on Re: Elysia diomedea feeding requirements by Cynthia Trowbridge. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Elysia diomedea

Related messages

  1. Sea Slugs from Costa Rica
    From: Victor Cespedes, March 24, 2010
  2. Larval rearing in Elysia diomedea
    From: Patrick Krug, September 23, 2008
  3. Re: Elysia diomedea feeding requirements
    From: Jake Weston, August 21, 2008
  4. Re: Elysia diomedea feeding requirements
    From: Jake Weston, August 19, 2008
  5. Re: Elysia diomedea breeding in home aquarium
    From: Skip Pierce, June 7, 2006
  6. Elysia diomedea breeding in home aquarium
    From: Matt Pedersen, June 5, 2006
  7. Are these 'lettuce nudibranch' eggs?
    From: Karen Hair, November 26, 2005
  8. Elysia diomedea life span
    From: Rebecca Rissanen, July 28, 2005
  9. Elysia diomedea from the Sea of Cortez
    From: Marli Wakeling, October 1, 2003
  10. Elysia diomedea from Ecuador
    From: Soledad Luna, August 21, 2003
  11. Elysia diomedea from Mexico
    From: José Luis Serrano, June 25, 2003
  12. Elysia diomedea from Costa Rica
    From: Peter Ajtai, June 2, 2002
  13. How to raise Elysia crispata
    From: Matt Galvin, December 19, 2001
  14. Re: How to raise Elysia crispata
    From: Erwin Koehler, December 19, 2001
  15. Re: Elysia diomedea
    From: Mary Jane Adams , June 9, 2001
  16. Elysia diomedea feeding requirements
    From: Sean, June 6, 2001

Show factsheet and all related messages