Sacoglossan feeding
• Williams, S.I. & Walker, D.I. (1999) Mesoherbivore-macroalgal interactions: feeding ecology of sacoglossan sea slugs (Mollusca, Opisthobranchia) and their effects on their food algae. Oceanogr. Mar. Biol. Ann. Rev., 37: 87-128. [A useful reference with tables of known sacoglossan food preferences.]
See also:
• Chloroplast Symbiosis References.
• Solar Powered Sea Slugs
• Chloroplast symbiosis Research
• Bryopsis Feeding
• Sacoglossan - general biology.
Rudman, W.B., 2001 (January 30) Sacoglossan feeding . [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/sacofeed
Related messages
Vaucheria litorea coevolution with sacoglossans
July 16, 2001
From: Matthew Crouch
Dear Dr. Rudman,
First, I would like to thank you for the site. It is very thorough and presents the material in a format useful to all interested parties, from seasoned researchers to the curious high school student.
I cannot believe that the presence of symbiotic chloroplasts in sacoglossans and similar organisms is not routinely discussed in relation to endosymbiotic theory (at least not in texts I have read). It would seem to be rather ...compelling... evidence supporting the theory. Second, although I am relatively new to this fascinating topic, I offer a few thoughts/questions on the evolution of the algae V. litorea. [see Liz Summer's message for photo.]
The Sacoglossans clearly benefit from the ability to incorporate chloroplasts into their metabolic pathways. Peculiarities in certain of the food species raise the possibility that the plants have been selected to facilitate this symbiosis as well. Dr. Rumpho has presented evidence concerning the unusual durability of the chloroplasts of V. litorea within the body of Elysia chlorotica with respect to other plant species. As described in a recent publication, the chloroplasts remained physically intact and continued to translate proteins for a rather unusual amount of time. This seems rather curious -- why should this particular plant species produce chloroplasts that are so much more stable in hostile environments (like those found in the interior of the sacoglossans)?
It is possible that the sacoglossans have taken advantage of the plant that produces the chloroplasts ideally suited for uptake and symbiosis. However, it also seems possible that the plants have seen selected to produce durable chloroplasts. My reasoning is that the feeding behavior of local slugs might be greatly reduced after they had incorporated symbiotic chloroplasts. Of course, the reverse could be true as well, but IF the plants could sate their predators and then survive, they would do much better than their neighbors who were being devoured by much more hungry Sacoglossans. Because of the benefits to the predators, the adaptation would be driven by pressure form both sides. The adaptation may have been forced by selective pressure from both species.
Anybody here know the relevant information concerning the feeding behavior of the sacoglassans before and after incorporating symbiotonts? It seems like feeding behavior would be wasteful after it was no longer needed (Being ignorant about sea slug physiology, I am assuming that the animal raches a maximum size and that its nutritional requirements therefore peak).
Most predictions I can think of would be the same no matter which way you look at it (one would expect the other prey plants to produce similarly durable chloroplasts etc). However, considering the evolution of the symbiosis an adaptation of the plant or multiple species (slug and prey) rather than merely one of the slug might lead to novel predictions or questions, especially concerning gene transfer from the plants to the slugs.
Would chloroplasts be coded to produce additional copies of the genes in the plant nucleus required for the operation and survival of the chloroplasts? (perhaps in a manner similar to plasmids in bacteria?) Perhaps the plants contain copies of the necessary genes or large quantities of very stable proteins coded by said genes in the cytoplasm itself , which are absorbed along with the chloroplasts? (evidence in Green et al, 2000). Would they be built to better resist digestive behaviour - a weird alteration of the exterior membrane maybe? Could genes be isolated in the plant which give such protection? Above all else, are there any other ways in which chloroplasts isolated from the prey species of the sacoglossans are different from other chloroplasts?
Again, my ignorance should be obvious. I doubt any of the above suggestions sounds feasible to the expert ear, but I wanted to offer the thought just in case it might be valuable and maybe stimulate a little thought about possibilities which might not be so farfetched.
Sincerely,
Matt Crouch
esperandus@hotmail.com
Crouch, M., 2001 (Jul 16) Vaucheria litorea coevolution with sacoglossans. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4814Dear Matt,
Thanks for your interesting thoughts. If you look thrugh the Forum you will find quite a lot of references to algal-slug symbioses, including the work of Mary Rumpho's group working on E. chlorotica and Vaucheria. One thing to keep in mind is that many sacoglossans have evolved this symbiosis, and they use chloroplasts from many different algae. In fact in at least one case a species changes the algae during its life history. If you look at the top of this page you will find links to further information and to many references on the topic.
Best wishes,
Bill Rudman
Re: Sacoglossans on Caulerpa
February 4, 2001
From: Cynthia Trowbridge
Dear Bill and Jeff,
Hi. In partial answer to Jeff's query about the sacoglossans that feed on Caulerpa in Australia, I found some details in Burn (1989).
• 1. Tamanovalva babai Burn feeds on Caulerpa scalpelliformis (and congeners).
• 2 & 3. Midorigai australis Burn eats only C. simpliciuscuala and Edenttellina typica Gatliff & Gabriel eats C. brownii.
• 4. Roburnella wilsoni (Tate) does feed on Caulerpa scalpelliformis (and congeners).
• 5. Oxynoe viridis (Pease) feeds on Caulpera spp. (Jeff, please note the Bill's photo of O. viridis on the Sea Slug Forum is shown on Caulerpa filiformis).
More specific details are in Burn (1989) as well as in the chapter by Burn in Mollusca: A Southern Synthesis. If your library does not have a copy of the latter, it might have a copy of this:
Burn, RD 1989 Order Sacoglossa. pp. 747-757 In: Marine invertebrates of Southern Australia. Part II. S.A. Shepherd & I.M. Thomas (Eds.). South Australian Government Printing Division, Adelaide.
All the best!
Cordially,
Cynthia
trowbric@ucs.orst.edu
Trowbridge, C., 2001 (Feb 4) Re: Sacoglossans on Caulerpa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3706Thanks Cynthia,
One of the things I would like to do when I get a moment is post some of my photos of the southeastern Australian bivalve sacoglossans on their algal food.
best wishes,
Bill Rudman
Sacoglossans on Caulerpa
January 25, 2001
From: Jeff Wright
Hello,
I was wondering if anyone knew the sacoglossan species associated with Caulerpa spp. in south-east Australia, particularly those on C. filiformis and C. scalpelliformis?
Thanks
Jeff
jtwright@ucdavis.edu
Wright, J., 2001 (Jan 25) Sacoglossans on Caulerpa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3509Dear Jeff,
I don't know if there is an actual published list with this information but most shelled sacoglossans feed on speces of Caulerpa. perhaps Kathe Jensen could help. Have a look at Mollusca - The Southern Synthesis, which has information on the known foods of most Australian sacoglossans. If your university library doesn't have a copy, it should.
Best wishes,
Bill Rudman
