Placement of Aherms

[Kirbster]

I know Ctenophore, among others, is keeping Dendronepthyea and other ahermatypics successfully. I have a question for those who do and something for us to chew on:

Do you place your ahermatypic corals as they would occur in the wild? In other words, extending out from a cliff face or growing upside down on the roof of a cave. A very experienced guy here told me he had afixed Tubastrea upside down and seen much greater feeding polyp extension. And it lasted for the long term.

I'm wondering if greater success would come with these corals, and perhaps others, like the ahermatypic Gorgonians and the weirdos like Distychophora (spelling?), if we kept them growing in a manner similar to that which they would assume in a natural cryptic habitat. This is secondary to proper food selection and proper current, of course, but it might be something to think about.

I know the Japanese were doing work with Gorgonians and rate of current (presented at 1997 WMC). And this coming year at MACNA, there is a guy from Israel I believe, supposed to talk about Dendronepthyea.

Just wondering if these corals have evolved to take advantage of their orientation with respect to gravity in similar ways as they evolve to current, feeding habits, etc. Most soft corals are positively phototropic - growing toward the light. Are they also negatively geotropic - growing opposite to the pull of gravity? Could ahermatypic corals actually be positively geptropic - preferring to hang upside down and grow with gravity?

KA

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"You must unlearn what you have learned."
-Yoda

[Kirbster]

No they don't care about light. It's like plants that live in scrublands. They don't like impoverished soil, they just grow there because they can and other plants can't. No competition. Ditto to Dendros et al in cryptic areas.

But I was getting more at any possible response soley to gravity, irrespective of light.

The flow studies with Gorgonians determined (going on memory of notes I've seen...I wasn't there) that not only do they prefer a laminar flow, but they show a response only to a "window" of flow rates. Above Y cm/sec or below X cm/sec and there is no response. And the windows were not particularly large and were specific to each species. Someone that has seen the research might want to correct me there, but that is what I got from it. Very interesting, I thought.

KA

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"You must unlearn what you have learned."
-Yoda

[Still Reefs]

Hey guys,

INTERESTING! This is a good topic to share on. I am scared to place a Dendronepthea in my small tank because it has a rapid pulsing flow for my SPS corals. I use to have a strong laminar flow but no longer! Perhaps I will try to make an area of low opposition flow for one of these beauties.

BTW: I favor "The Next Level", I think it is a good idea.

Thanks,

[Still Reefs]

Ctenophore,

Thanks for the advice. I will probably avoid the dendro's due to lack of space and conflicting currents. My tank has a plenum that has been established for about 3 years and it gets daily doses of Isochrysis, Nanochloropsis and Tetraselmis. I have had no problems keeping various Gorgonians species. All in all, thanks for the concern. It shows that you are looking out for the corals best interest.

Thanks again!


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Sean Bradley
Photographer : Still Reefs Photographic
Productions
<A HREF="http://www.stillherps.herpexchange.com/stillreefs
" TARGET=_blank>http://www.stillherps.herpexchange.com/stillreefs
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[horge]

Kirbster:

I know of an exchange between SWMichael and a Dive Magazine photographer that touches on orientation and location of Dendros. It appeared in an issue of AFM that I'm presently looking for. The photog stated that Red Sea specimens were fairly-frequently upright and exposed, as opposed to the stereotype of caved and hanging bat-like. Scott responded with the 'dried' and tested "competition for space is responsible" for their stereotyped photodeprived habitat. It was interesting for the anecdotal evidence vs. anecdotal evidence charm, and you might look it up.

Considering the size of animal and the relative diameters of the fluid and nutrient transport highways in the animal (internal pressure and all that), I would never have suspected gravity playing a key role in morphology. Interesting thought though.

I would have thought the unidirectional flow preference should have been obvious to those who have observed this Genus in the wild with care over the past several decades decades. I guess it was just a matter of formal publication.

However, I would caution against an interpretation that these animals can't take oscillating water displacement. A quick trip to the underwater underhangs off the southern
end of my island, will show you what they sometimes have to deal with each time the tide hetts up. And these are sizable specimens i sizeable quantity. FWIW

horge

[horge]

Ctenophore:

I know the high regard in which Mr. Toonen is held by a lot of online reefers. If my qualification was interpreted as doubt in his 'suggestion', you were mistaken.

It is precisely because you cannot easily do much more than provide 'aquarium-scale oscillation' within an aquarium that I posted. Someone with no experience of natural currents MIGHT be misled into thinking that aquarium-scale oscillations don't fall under laminar flows of any periodicity.

The fact that you excerpted from a post directly above, in boldface, might suggest to some that you feel I am questioning the good Mr. Toonen. Not so. But rest assured I will not hesitate to question him, you or anyone else on facts (or interpretation of the same) if I feel it furthers understanding of the issue.

There was no harm meant in my post above, nor will there ever be.

[This message has been edited by horge (edited 01-05-2000).]

[Reef Junkie]

Kirbster,
Hey. There is a Marine Biologist here in NY by the name of Joe Yaiullo. He kept Tubastrea at the Brooklyn Aquarium and actually some colonies spawned. When they spawned the planaria settled in all kinds of directions. At the time there was a lot of talk about keeping Tubastrea. The suggestion for keeping them hanging upsidedown in the tank was also discussed. There where a few that tried it, but I never did hear of what happend to the colonies. Personally, I would think if your tank where saturated or at least semi-saturated with plankton of some sort it wouln't be a problem to keep them upside down. They'd be free of settling debris, but harder to target feed. I keep a colony of Tubastrea faulkneri. The colony was a rescue from a LFS and was in bad shape. It's been just over a month and the tissue around the base of the coral is growing back and new polyps can be seen growing out of the sides of the coral. They were probably there before I bought the coral. The coral is in full light on the bottom of the tank. It will open for feedings during the day, but always opens up after the halides go out. I'm sure if I kept it hanging upside down that it might open up more often, but again it would be hard for me to target feed. I like this thread.
later,
Bill

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http://www.homestead.com/reefjunkie/highenergy.html

[horge]

I would imagine the upside down orientation stereotypically assumed by ahermatypics is an artifact of the danger of abrasion or outright burial by bottom sediment --in the context of the marginal locations they have been cornered into.

The fact that quite a number of them are found upright in those few marginal locations where bottom abrasion/burial is not a danger suggests they haven't specialized too far, and suffer not for standing up.

[horge]

I am laid low by guilt.
You have my humblest of apologies, Ctenophore.

I was and maybe still am raw from the ...rather hectic nature of the other board.
I had no right to read anything into your post, as everything about this board is refreshingly gentle. I would have left the other board but I feared leaving smacked of backing down from a righteous struggle.
Would that I would relearn careful thought and gentle speech from you and the others here!

Forever in your service,
horge

[Kirbster]

This is why I need to start diving. I need to see these things in the wild.

Horge, I take it you believe gravity to have no affect on growth patterns - or at least effects negligible in relation to the effects of light and current? I suppose that makes sense, considering (as you did) the physiology of the animals. This never would have tickled my brain if it hadn't been for hearing about it from people that have otherwise proven to be quite sane.

As far as the aherms reasons for inhabiting certain niches, I guess that needs to be addressed by evolutionary biology. Is the lack of photosynthetic symbionts an evolutionary advancement to accomodate corals unhappy with conditions in illuminated environments? In other words, they don't show up there just because they are the only ones that can (my original assertion), but that they evolved away from the dependence on light to take advantage of a broader range of habitats. A useless argument in terms of my original question.

Horge,

Your input is very welcome here. It seems that here we can all discuss things intelligently and disagree vehemently without anyone getting uptight or whining about being insulted. Virtually the polar opposite of Aqualink.

Thanks,

KA


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"You must unlearn what you have learned."
-Yoda

[horge]

Kirbster

Why yes, I do believe gravity to be minimal as a factor in morphological development. The centrifugal in-tissue influence from current-generated swaying plays whack with the cellular 'perception' of gravity anyway.
About that 'irrelevant argument', hehehe:
Good bait, kirb, and I'm hooked.

Call me a crab, but I wonder about the applicability of DNA-based palaeontology when it comes to an adaptation like zooxanthellae-hosting. The fossil record likewise is of depresingly limited use in distinguishing between herms and aherms and finding who came first.

The very fact that I call zooxanthellae-hosting an ADAPTATION gives away my sentiment(Drumroll please)...
The seas were ruled by aherms which didn't give a hoot about gravity. Then, enter the adaptation to host zooxanthellae, which made it important to face upward.
BOINGGG! If you have a weighted skeleton, you have the advantage because your polyp always faces up, so those mutant herms that secreted minerals into attached structures had a huge advantage.
Furthermore, the durability afforded by skeleta allowed them to occupy --heck, build up to-- ever higher (and more turbulent) zones in the water column, closer...to...the...light!!!
(fanfare)

Too simple? Of course, and therefore wrong.
Potshots are very welcome, but I have to say that the above focuses on the split between herms and aherms, with a slant towards including gravity as an emergent factor. I unfortunately view things from a form-follows-function standpoint, which is far too logical for application to the madhouse mechanics of evolution.
Oh, am I ranting again?

Sorry for the numerous re-edits, but so long as no one else has posted yet...hehehe...I'll give your server the extra workout.

[This message has been edited by horge (edited 01-06-2000).]

[horge]

Good one. Both the pun and the point.
To pile on:
Digestion resistance is a good defense for any small prey: it (i.e. algae) can pass through the predator's gut unharmed. It's probable that that's how zooxanthellic (I also prefer your terminology, thanks) symbiosis started.

Herbivores (or just those whose feeding habits involved incidental ingestion of such algae) benefited from photosynthetic activity in the gut, and somehow managed to incorporate the photosynthetizers into more-efficiently-lighted parts of their anatomy.

Of course, this raises the question of why phytoplanktivores like the Dendroneps of the original post, DID NOT evolve to utilize any photosynthetic fringe benefits. Could be anything from local photodeprivation, etc. Hehehe. This is interesting.

Do you actively provide food inputs for your Dendroneps, ctenophore?

[horge]

Seems we're arguing toward each other. If we keep this up for a few more months, we might be trading positions. hahaha.

I'm presuming 'Ron' would be Dr. Shimek. Sorry, but I'll be Mr. Newbie for quite some time!