[KrakenSeas]

Tell me everything i need to know about keeping these corals thriving.I might try a red one when i return from vacation.Thank You

[Ninong]

Well, obviously it would prefer a low light area. Do you have any overhanging rocks or cave type formations in your rockwork? And, of course, it should be fed phytoplankton and microzooplankton daily, perhaps even twice daily--dawn and dusk. They would have a better chance of survival in a mature tank with a very active deep sand bed and might do better in a tank without a protein skimmer or one that is only lightly skimmed. They are quite beautiful but are considered difficult to keep since they are azooxanthellate.

Ninong [img]/ubb/smile.gif[/img]

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Irrational Exuberance!

[Biomanjcs72]

Baywatch Babe, I have to ask, was the whole post an excerpt from Hugo's (Eric's) book/article, or was just the last part?

[Baywatch Babe]

From his article -> http://www.aquarium.net/1296/1296_4.shtml

[Biomanjcs72]

[quote]Originally posted by Baywatch Babe:
[b]They are exclusively ahermatypic, meaning all species lack zooxanthellae required for photosynthesis

Is a really funny statement because a more precise statement is "They are exclusively ahermatypic, meaning all species lack the photosynthetic zooxanthellae." While it is correct (of course) that zooxanthellae are "required" for photosynthesis, they are the photosynthesis, not simply a piece of the puzzle.

I'm just nitpicking...not trying to get under anyone's feathers. [img]/ubb/smile.gif[/img]

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JCS
Some days you get the bear, some days the bear gets you.

[Biomanjcs72]

Sorry about that last post, I work in a Law Firm and sometimes (a lot of the time) I get hung up on semantics.
I did't mean anything against Eric at all. He's a great guy, really knows his stuff. [img]/ubb/wink.gif[/img]

[Humilis]

I may add that it needs high water movement.

[Baywatch Babe]

They are exclusively ahermatypic, meaning all species lack zooxanthellae required for photosynthesis. Without the symbiotic algae, these corals require a continual wash of phytoplankton across their polyps in order to survive. Dendronepthya hemprichii, sinaiensis and Scleronepthya corymbosa have been found to be almost exclusively phytoplankton eaters, and to actually capture very little zooplankton. This makes complete sense, since phytoplakton is smaller, easier to capture, and these soft corals have relatively undeveloped stinging cells. Thus zooplankton, as previous thought to encompass their main diet, would be hard to capture with such "wimpy" nematocysts. Indeed, captive conditions may be possible using a regular feeding of phytoplankton, however, the amount of food required would still be extraordinarily difficult to cope with in a closed system.


Most ahermatypic corals are found in shaded or mostly shaded areas of the reef. Though most Dendronephthya are indeed found in the wild under ledges, overhangs, and in caves, many specimens can also be found on reef slopes in full sunlight. This is especially true for those examples found in the Red Sea. Thus, light does not seem to be harmful to some species, despite a preponderance found in dimly lit areas.

In the aquarium, all the amazing properties of Dendronephthya become insignificant. Why? Because they don't survive. Despite massive importation of these corals, many refuse to expand even once upon introduction to captive conditions. They remain in a collapsed state until the tissue dissolves away. Some specimens may adopt a more Goniopora-like pattern where they may expand well for a time, and then slowly begin to expand less and less until they have wasted completely away. Of course, like many corals, there are occasional sitings and claims of hobbyists who have kept Dendronepthya alive for years. I have never personally known this to be the case. In any event, I believe the factors which would allow for the success of this coral in aquariums, even if the claims were true, would be incomplete and not reproducible. It seems as though very heavy feeding of zooplankton and detritus, strong continuous and non-laminar current, and adequate placement with regard to light would be essential to their survival. In any situation where such heavy feeding must occur, there is the downside of having to somehow dispose of the high nutrients that would predominate in such a closed system, either mechanically or biologically. Wilkens has suggested that heavy skimming and heavy feeding has allowed him to keep certain species for a period of years in systems designated almost exclusively to the needs of these and similar corals.
-an excerpt from Eric Borneman's <A HREF="http://www.aquarium.net/1296/1296_4.shtml" TARGET=_blank>Dendronephthya:
A Seduction of Allusions and Illusions</A>

[Doug1]

In regards to Ahermatypic as opposed to azooxanthelate. The terms have been used interchangably for a while now causing a lot of confusion. After having the difference in the meaning of the 2 terms hammered into me during MACO coral biology class(taught by Eric) I asked him if azooxanthelate wouldn't have been a better term. He said yes.
Zooxanthellate refers to being photosynthic be virtue of harboring photosynthesising dinoflagelates in the tissue of a coral. Azooxanthellate animals(such as dendronepthea) have none and are dependent on prey capture as pointed out.
Hermatypic refers to the ability to contribute to the reef platform via the formation of a carbonate skeletal structure. This is mainly the provence of the schleractinian corals, what are refered to as Large Polyp and Small Polyp stony corals, a distinction with no use in scientific circles(its a trade descriptor)
The vast majority of reef building corals also happen to be photosynthic, but then so are a lot of Octocorals, refered to as soft corals, lacking carbonate skeletal structure. With only a few exceptions these are not hermatypic(reef building) though they are definatly zooxanthellate(photosynthic)
Hope this clears that up, I only had to read and reread about a thousand times&lt;G&gt;

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Reef as though your life depended on it, yours might but the seas does
Visit www.thereeftank.com User friendly and flamefree Doug TheReefTank admin

[Ninong]

Yes, as a matter of fact, in Borneman's new book, Aquarium Corals: Selection, Husbandry, and Natural History, he has decided to start using hermatypic and ahermatypic in the correct narrow sense of the word, meaning reef building or non-reef building, and to use zooxanthellate or symbiotic to indicate photosynthetic corals, and azooxanthellate or aposymbiotic to indicate nonphotosynthetic corals.

Gia, you're quoting Borneman as saying: "This makes complete sense, since phytoplankton is smaller, easier to capture, and these soft corals have relatively undeveloped stinging cells. Thus zooplankton, as previous thought to encompass their main diet, would be hard to capture with such "wimpy" nematocysts. Indeed, captive conditions may be possible using a regular feeding of phytoplankton."

And then, in the last paragraph as saying: "It seems as though very heavy feeding of zooplankton and detritus, strong continuous and non-laminar current, and adequate placement with regard to light would be essential to their survival."

OK, I will assume that the contradiction here is simply a typo, since he was pretty clear that he thinks that the diet of Dendronephthea is primarily phytoplankton. I don't know when he wrote this article, do you have a date for it?

Dendronephthea is one of the most active and successful of all the octocorals. And they do not capture prey with nematocysts like scleractinians. Octocorallia do not have the same feeding mechanisms as hexacorallia. For one thing, hexacorallia have a lot more powerful cnidocil than octocorallia. Chemoreceptors in the tentacles of scleractinians sense minute concentrations of amino acids excreted by the prey which triggers the feeding response in the polyp. The prey is immobilized by the cnidae and captured by the tentacles and/or mucus net.

That's not the way it works in octocorals at all. Octocorals are much more ancient than scleractinians and employ a quite different method of catching their prey. They employ mostly direct mechanical seizure of the prey with their motile tentacles armed with pinnules at the edges. The reaction of the tentacles is very quick, triggered by tactile contact of the prey with the tentacle or pinnules. The polyps grab not only moving prey but also other floating food objects, like cysts, eggs, detritus, fish feces, mucus flakes, etc. The prey or food item is immediately transferred by the tentacle to the mouth and swallowed.

I am unable to find recent studies of the gut contents of Dendronephthea spp., although I did find gut content analysis of Xenia spp. that included planktonic crustaceans, small polychaetes, veligers, and eggs of invertebrates. And I did find a photo study of Dendronephthea that was done in situ using strobe photography that recorded them catching and swallowing planktonic crustaceans and veligers. Dendronephthea seizes prey by swiftly bending one of the tentacles, which together with the pinnules, form a kind of trap, grabbing the food particle. Then the prey is pushed by the tentacle into the mouth of the polyp. Their reduced cnidocil could not be used in the capture of large prey but probably could be used for catching microzooplankton.

Another difference in feeding response between octocorals and scleractinians is that with octocorals you get an instant reaction of a group of polyps together when one of the polyps in the group has been triggered by contact with potential prey. You do not have this reaction in scleractinians.

Anyway, getting back to what Borneman seems to be saying, he is saying that Dendronephthea feeds mostly on phytoplankton and very little zooplankton. This is correct but I'm not sure exactly what he means by "very little zooplankton," because it definitely does feed on zooplankton, especially microzooplankton. He seems to be making the point that this is because they have "wimpy" nematocysts, but all octocorals have wimpy nematocysts and it doesn't prevent them from feeding on zooplankton because they use a different feeding mechanism which is based more on mechanical capture of the prey. That's why I was wondering when he wrote that article.

Regards,

Ninong [img]/ubb/smile.gif[/img]

P.S. - I fully agree with his conclusion that Dendronephthea is difficult to keep in home systems because of their need for constant feeding on a variety of phytoplankton, microzooplankton, bacterioplankton, DOM, etc.



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Irrational Exuberance!

[Doug1]

Ninong heres the link to the article, I believe new evidence may have surfaced since it was written http://www.aquarium.net/1296/1296_4.shtml


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Reef as though your life depended on it, yours might but the seas does
Visit www.thereeftank.com User friendly and flamefree Doug TheReefTank admin

[Alice]

Ninong;

Good info as always. Thank you! Do you have a link to the gut analysis done on the Xenia? I had always thought they were pretty close to autotrophic?

~Alice

[Ninong]

Originally posted by Alice:
Ninong;

Good info as always. Thank you! Do you have a link to the gut analysis done on the Xenia? I had always thought they were pretty close to autotrophic?

~Alice

Yes, there's a Catch 22 there that is the reason most people think that xeniids are strictly autotrophic.

Here is an except from Coral Reef Ecology (1995) by Prof. Dr. Yuri I. Sorokin, Univ. of Queensland, page 360:

"In his study on nutrition of a variety of octocorals Lewis (1982) offered them various kinds of zooplankton, and also investigated the gut contents of polyps in specimens taken at the reef and immediately inspected. He established that among the 24 species thus checked some did not catch any animal preys under experimental conditions. Among them were the symbiotic species Sinularia capillosa, Eunicea tourneforti, Paralemnalia digitiformis, Plexaura flexuosa, and Gorgonia ventalina. The same was valid for the xeniids. Nevertheless, when analyzing the guts in xeniid specimens caught in nature he found in some of them planktonic crustaceans, small polychaetes, veligers, and eggs of invertebrates. Probably, to catch the food the polyps of xeniids need to be kept permanently in motion by waves on the shallows where they are living. Other octocorals studied, both their symbiotic species and genera (Lobophytum, Sarcophyton, Sinularia densa, Capnella, Lemnalia, Isis, Juncella, Pseudopterogorgia, Plexaura, Telesto, Tubipora), and the asymbiotic ones (Dendronephthea, Rumphella, Briareum, Muriceopsis, Gorgonia) were observed catching and swallowing the planktonic crustaceans and veligers.

With a view to the variability of feeding strategy in different taxa of octocorals, we have investigated the spectrum of feeding in a selection of coral species, which inhabit reefs in the Indian Ocean and the GBR, employing the radiocarbon method. To the specimens of corals acclimated to experimental conditions various kinds of labeled food were offered excluding so the influence of their physiological state on the results on the experiments. The typical results are given in Fig. 9.7. In general, they proved the basic conclusion on the ability of most octocorals for predatory feeding. Second in importance among the sources of their feeding were the bacterioplankton and DOM. The most active predators among the octocorals tested were their asymbiotic species Dendronephthea, Spongotes, Bebryce, Acabaria. The gorgonian Mopsella was found to be feeding also on phytoplankton."


Ninong [img]/ubb/smile.gif[/img]



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Irrational Exuberance!

[Ninong]

Originally posted by Doug1:
Ninong heres the link to the article, I believe new evidence may have surfaced since it was written http://www.aquarium.net/1296/1296_4.shtml

Thanks for the link. Looks like that article was copyrighted 1996. I haven't finished Eric's new book yet, in fact, I have just barely begun to read it (it is excellent), so I can't say whether he has modified any of what was said in that article. I do know that his new book was peer reviewed by people we would consider to be experts prior to going to press.

OK, I just looked it up in his new book and here is an excerpt:

"Dendronephthya are entirely aposymbiotic. In nature, they are voracious feeders, directly absorbing many nutrients, and almost constantly feeding on phytoplankton and/or zooplankton. According to one study with D. hemprichii, zooplankton comprise only an incidental part of their diet (Fabricius, 1995). However, Sorokin (1991) found another Dendronephthya species to be among the most active predators of aposymbiotic octocorals he had studied, throwing into question the popular assumption that all members of this group feed on algal plankton. They have actually been observed producing sweeper tentacles in the wild."

So, yes, it appears that he has expanded his understanding of the feeding of Dendronephthea since he wrote that previous article.

Ninong [img]/ubb/biggrin.gif[/img]


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Irrational Exuberance!

[Alice]

Thanks, Ninong. I haven't taken the plunge into Sorokin yet [img]/ubb/wink.gif[/img] If I can prevail on you yet again, were there any references to the size of the prey found in the xeniid gastrovascular cavity? Just wondering about comparative foods that can be offered in the aquarium in terms of size.

~Alice

[Ninong]

Alice ~

There were no sizes given in that particular instance. However, one of the things that I noticed in several of their feeding studies is that the feeding habits of many animals may not be the same under experimental conditions as they are in the wild.

This text, by the way, has more charts and statistics, and references to field studies than any book I have ever seen. There are fully 2,000 cited references in the back of the book (35 pages worth). Many of the studies were performed by the author over the past 35 years. They set up elaborate studies in situ using timed strobe photography and other methods, and they set up large laboratory experiments in tanks larger than 1,000 gallons. They labeled food with radiocarbon to measure intake and then measured ^14CO2 in respiration to measure assimilation.

It is a wonderful text but someone should have proofread it before it went to press. By my estimation, there are at least 2,000 typos and misspellings. One thing that is helpful for anyone who wishes to pursue a topic further is that the cited reference is in parentheses next to every statement in the body of the text. And every other page has a chart showing the results of the study in question. It is tedious reading compared to more popular works, like Borneman's new book, but it is so detailed that it is fascinating. In some instances the author will critique an earlier conclusion by an expert in the field maybe 50 years ago and then show how more recent studies contradict the earlier work. He also goes into detail in explaining why a recent large study is too inadequate and flawed to be meaningful, and why it is impossible to set up because of the thousands of variables.

There are no suppositions in this book. Every statement is backed by references to actual studies that have been done--usually several studies. He even discusses studies that resulted in slightly different conclusions and explains how their different methods affected the results and what he thinks should have been done differently.

There is an enormous amount of detail on the interactions of the various reef communities, from sediment dwellers on up. This may be the most valuable content in this book compared to other easier reads. All I can say is that there is nothing in here that in any way contradicts the natural approach advocated by people like Dr. Ron.

Ninong [img]/ubb/biggrin.gif[/img]

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Irrational Exuberance!

[Alice]

If I remember correctly, Sorokin's book was translated from Russian to German and then to English? I have heard that it is an excellent reference book. I've got a search being done for a used copy, (ha! a new copy has been hard to locate for some folks, but I know someone who found it at their local public library!) so I can add it to my reference library.

~Alice

[This message has been edited by Alice (edited 05-14-2001).]

[Ninong]

Alice ~

Hmmm... that makes sense, about the translations. Because it is obvious from his early academic background, and his name, that he is Russian. The book was published in Germany and all of the copyrights are German. Some of the place names retain German spellings and there are tons of misspellings that should have been caught but weren't. I thought he might have written it in English since he has been working in Queensland, Australia for some time now (I'm not sure how long). The translation is better than the German to English translation of Giant Clams by Daniel Knop.

The hardcover version of the revised edition is out of print. I have the softcover edition, which is available at a lot of college bookstores online since it is a popular marine science textbook. The price seems to be $81.95 plus shipping every place I found it. Nobody discounts it and it usually takes three to four weeks to get it. I ordered it from Borders.com because they listed it as the hardcover edition for $81.95 plus $4.29 shipping. Well, I received the softcover version, so I e-mailed them to complain. They double checked and found out that the hardcover is out of print and that they had a mistake on their website. They gave me a refund of 25% ($20.50), so I decided to keep it.

Ninong [img]/ubb/biggrin.gif[/img]

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Irrational Exuberance!

[tdwyatt]

test

[tdwyatt]

Sorry for the test on the thread... I have read with interest the entire thread, I don't see any problems, and I applaud the mention of the hermatypic Vs ahermatypic references. The Sorokin is indeed a translation from the original Russian to German, but was initially printed in German. The translation to English is obvious when trying to read the text, as the syntax is often, well, difficult at best, but the information is invaluable. It gives much backup to many new concepts that are being promulgated for the how's and why's of reefkeeping, and opens many new doors to areas that may be the next level of reef aquaria. Eric had mentioned that when developing the syllabus for the MACO class, there were few all-encompassing texts available to use. Sorokin is one, as is the 2 volume set by Tomas Tomascik, "The Ecology of the Indonesian Seas". These books are sporadically available through sources in Indonesia, and although B&N and Amazon and Borders often list these books, they are more often not to be found. A better source would be smaller specialty companies like Andrews Isles in OZ, etc. Interesting thread, I need to come to this BBS more often...

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