lettuce nudibranchs
- Thread starter scottbeth
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scottbeth,
You still have provided very little information, so it is difficult for me to provide you with any assistance. First, I do not even know if you really do have an Elysia spp. sea slug or what species you may have. Also, do you currently have at least two of the same species of slug in your tank? Is the tank in question the one in your signature?
There are many different types of sea slugs. There are the colorful and popular nudibranchs, all of which are carnivores; sea hares, all of which are herbivores; and "solar-powered" sea slugs, which suck chloroplasts out of the algae they feed upon and retain the living chloroplasts in their body for their own use for a certain amount of time. These aren't the only "types" of sea slugs but a few select types. "Lettuce" slugs can cover three or more species in the genus Elysia that are common in the trade. Little is known about the dietary preferrences of the Pacific species; the two Atlantic species were thought to be one and the same until a few years ago.
These sea slugs are hermaphrodites that do not self-fertilize (I can't say it is impossible, since I can't prove it is impossible, but....) I know a very credible couple who owned only a single Elysia which laid eggs on occassion, but they were never fertile. A fertile egg ribbon will hatch out in just a few days, and will appear to disinegrate, although some fish will nibble at the egg ribbons to "help" the process along. As far as I am aware, all the Elysia spp. hatch out as veliger larvae, which are planktonic. Some species are in this planktonic state for weeks and require a suitable unicellar algae to feed upon, whereas others move from hatching to settlement/metamorphosis in such a short period of time (say, less than 72 hours) that they do not require a larval food.
As there is little data on the algae species that most adult Elysia spp. feed on, it should come as no surprise that very little is known about their larval dietary preferrences. Dr. Sidney Pierce has worked with different species in the genus and speculates that some species will not metamorphose unless the algae that will compose their diet in the future is present. Not only is information on larval and adult diets largely unknown, but species often have a specific algae species that they feed on as juveniles that is different than their adult macroalgae diet, and each species have a high degree of specificity regarding their food selection.
This all said, certain Atlantic lettuce sea slugs have been "reared" by hobbyists in tanks. The slugs generally accomplish this by themselves without any "help" by the tank's owner. This usually only happens in tanks without skimmers and sumps, as large effective pumps would kill the larvae before settlement. The reason this sometimes occurs with one of the Atlantic lettuce slug species is that adults of that species can survive on the same algae species of their juveniles, Bryopsis (although the adult does not normally continue to feed on this algae.)
You still have provided very little information, so it is difficult for me to provide you with any assistance. First, I do not even know if you really do have an Elysia spp. sea slug or what species you may have. Also, do you currently have at least two of the same species of slug in your tank? Is the tank in question the one in your signature?
There are many different types of sea slugs. There are the colorful and popular nudibranchs, all of which are carnivores; sea hares, all of which are herbivores; and "solar-powered" sea slugs, which suck chloroplasts out of the algae they feed upon and retain the living chloroplasts in their body for their own use for a certain amount of time. These aren't the only "types" of sea slugs but a few select types. "Lettuce" slugs can cover three or more species in the genus Elysia that are common in the trade. Little is known about the dietary preferrences of the Pacific species; the two Atlantic species were thought to be one and the same until a few years ago.
These sea slugs are hermaphrodites that do not self-fertilize (I can't say it is impossible, since I can't prove it is impossible, but....) I know a very credible couple who owned only a single Elysia which laid eggs on occassion, but they were never fertile. A fertile egg ribbon will hatch out in just a few days, and will appear to disinegrate, although some fish will nibble at the egg ribbons to "help" the process along. As far as I am aware, all the Elysia spp. hatch out as veliger larvae, which are planktonic. Some species are in this planktonic state for weeks and require a suitable unicellar algae to feed upon, whereas others move from hatching to settlement/metamorphosis in such a short period of time (say, less than 72 hours) that they do not require a larval food.
As there is little data on the algae species that most adult Elysia spp. feed on, it should come as no surprise that very little is known about their larval dietary preferrences. Dr. Sidney Pierce has worked with different species in the genus and speculates that some species will not metamorphose unless the algae that will compose their diet in the future is present. Not only is information on larval and adult diets largely unknown, but species often have a specific algae species that they feed on as juveniles that is different than their adult macroalgae diet, and each species have a high degree of specificity regarding their food selection.
This all said, certain Atlantic lettuce sea slugs have been "reared" by hobbyists in tanks. The slugs generally accomplish this by themselves without any "help" by the tank's owner. This usually only happens in tanks without skimmers and sumps, as large effective pumps would kill the larvae before settlement. The reason this sometimes occurs with one of the Atlantic lettuce slug species is that adults of that species can survive on the same algae species of their juveniles, Bryopsis (although the adult does not normally continue to feed on this algae.)
Elysia, I appreciate your help. The species I have is elysia crispata. I have 2, maybe 3 (haven't seen the 3rd in a while). They are in my signature tank, which is sps dominated. The eggs were laid on the sept. 24th after what looked like a sexual dance between 2 of them. This lasted for approximately 1HR. The eggs are a white curled string, firmly attached to live rock and bryopsis. I have pics and will cont. to try to get them posted. I do have alot of flow and a sump and a very strong skimmer, so should they be quarantined? Thanks and forgive my level of expertise on sea slugs.-------------Scott
Scott,
I'm not an expert on sea slugs either, but considering how many posts I look at on RC that mention "slugs" that turn out to be snails, I usually like to get a positive ID before I get all long-winded about these guys. Are you reasonably sure your slugs are E. crispata and not E. clarki? The easiest way to tell the difference is by the color of the foot of the slug. E. clarki's digestive branches go into the foot, so it is green with translucent white spots, while E. crispata's foot is opaque white (i.e. there are no digestive branches located there.)
Both species have "lecithotrophic larval development," which means that the planktonic larvae do not feed. I have read that the time spent as veligers can last anywhere from two to five days, after which the larvae metamorphose into juvenile slugs.
According to the seaslugforum, the juvenile food of E. crispata is unknown, while the adults feed on Halimeda incrassata and Penicillus capitatus. E. clarki, on the other hand, have juveniles that will feed on Bryopsis plumosa and have been maintained in a lab on this food only for many months. In their natural habitat, E. clarki adults would stop feeding on Bryopsis and begin to feed on two Halimeda spp. and two Penicillus spp.
If you are lucky enough to have your slugs lay egg ribbons on live rock that can be easily moved out of your system and placed elsewhere, it may be a good idea. Often times, the slugs seem to lay their eggs on the aquarium walls (or perhaps these eggs are just easier for us to notice.) Do you have a 'fuge, and does it have a much reduced flow? It is possible that the eggs would not require any water movement at all, but I would imagine that gentle water movement would be beneficial.
Its good to know that your reef is SPS dominated, as these sea slugs will at times be in the water current floating from rock to rock (I'm not sure how often this is intentional, but I have witnessed it in various tank set ups.) They have very few defenses, and anemones and certain LPS will consume them. Its a good idea to cover all pump intakes if you can.
If you do have E. crispata and are successful getting some of the veligers to metamorph, you can investigate with some Western Atlantic algaes. Perhaps one will work. Just remember that it often doesn't appear that these slugs are feeding at all, since they are removing (by sucking) the contents of the algae wall, rather than consuming the entire cell like a sea hare would do.
Good luck. They really are interesting animals.
I'm not an expert on sea slugs either, but considering how many posts I look at on RC that mention "slugs" that turn out to be snails, I usually like to get a positive ID before I get all long-winded about these guys. Are you reasonably sure your slugs are E. crispata and not E. clarki? The easiest way to tell the difference is by the color of the foot of the slug. E. clarki's digestive branches go into the foot, so it is green with translucent white spots, while E. crispata's foot is opaque white (i.e. there are no digestive branches located there.)
Both species have "lecithotrophic larval development," which means that the planktonic larvae do not feed. I have read that the time spent as veligers can last anywhere from two to five days, after which the larvae metamorphose into juvenile slugs.
According to the seaslugforum, the juvenile food of E. crispata is unknown, while the adults feed on Halimeda incrassata and Penicillus capitatus. E. clarki, on the other hand, have juveniles that will feed on Bryopsis plumosa and have been maintained in a lab on this food only for many months. In their natural habitat, E. clarki adults would stop feeding on Bryopsis and begin to feed on two Halimeda spp. and two Penicillus spp.
If you are lucky enough to have your slugs lay egg ribbons on live rock that can be easily moved out of your system and placed elsewhere, it may be a good idea. Often times, the slugs seem to lay their eggs on the aquarium walls (or perhaps these eggs are just easier for us to notice.) Do you have a 'fuge, and does it have a much reduced flow? It is possible that the eggs would not require any water movement at all, but I would imagine that gentle water movement would be beneficial.
Its good to know that your reef is SPS dominated, as these sea slugs will at times be in the water current floating from rock to rock (I'm not sure how often this is intentional, but I have witnessed it in various tank set ups.) They have very few defenses, and anemones and certain LPS will consume them. Its a good idea to cover all pump intakes if you can.
If you do have E. crispata and are successful getting some of the veligers to metamorph, you can investigate with some Western Atlantic algaes. Perhaps one will work. Just remember that it often doesn't appear that these slugs are feeding at all, since they are removing (by sucking) the contents of the algae wall, rather than consuming the entire cell like a sea hare would do.
Good luck. They really are interesting animals.
I'm pretty sure they are crispata, the digestive branchs do stop at the foot. I can't see the bottom of the foot because they never go up the front of the tank. The eggs are on live rock with about 10 sps colonies, so I can't remove the rock, but can remove the eggs with bryopis if this is advisable. They are in an area of bright light and high intermittent flow. I'm 5 days into the eggs being laid and if I need to remove them it should be soon. My fuge has good flow with live mudd, live sand and live rock but not much room due to a large skimmer. I have 2 other compartments in the sump; sump supply- lots of flow, and the return area which probably isn't a good idea either. I also have 2-10gal frag tanks-could this work? Thanks-----Scott
If the eggs are fertile, they will likely lay some more. The frag tanks sound like they could work, especially if they are for your sps. I have read that certain crab larvae are very delicate and one of the reasons why crabs rarely successfully produce offspring in tanks is because simply hitting the glass (while the larvae are planktonic) kills them. Obviously, not all larvae are that delicate, but it makes sense to make it as easy on them as possible. Since the slugs do not feed as larvae, I do not know if they really need to be "planktonic" during that time period. I vaguely remember reading that researchers were working with the larvae on petri dishes. So you can attempt to move any of the egg masses that you see over to the frag tanks and see how they do. You will need to add some bryopsis along with the larvae... If there are any bryopsis covered small rocks in your display, perhaps you could move one over and attempt to contain the algae in a "box" made of plastic canvas (like you get at craft stores) and zip-ties? I know that hair algae is practically impossible to contain, but it may help.
J. Montgomery
Mouth Pipetting
A few years ago I bought some lettuce nudis from Reeftopia (IIRC):
They only survived a few weeks before each one found my MJmod, but not before laying eggs:
A few weeks later I spotted this little guy:
After I few days I never saw it anymore.
They only survived a few weeks before each one found my MJmod, but not before laying eggs:
A few weeks later I spotted this little guy:
After I few days I never saw it anymore.
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