Night Lights and Polyp Extension

[C. Eymann]

I know, and I am telling you that nearly all of the difference that you are seeing between night and day is because of gas exchange. The polyps are out more at night because the corals need them to extend more to respire since photosynthesis is not providing this benefit to the coral during the night hours. It is that simple.

Levy et al., mentions this behavior being circadian, which sparked an interesting debate that I watched at a show about two decades ago, or so, in St. Louis. They were trying to figure out if this was physiological or if it was environment. Unfortunately, no conclusions were reached.

AGAIN, are you referring to PE in general? or specifically axial corallite polyps? because what I have quoted /posted mentions axial corallite polyp extension is a nocturnal feeding response, says nothing about axial corallite extension behavior and gas exchange

 

[jda]

You are missing it or appear to be seeing what you want to see...

Polyps are always used for gas exchange, sure. During the day, the polyps do not NEED to be out much since the zoox can help with gas exchange. They are out more at night since they NEED TO BE to breathe (bad choice of words).

Even though they do have to breathe all day, the PE is more at night because it needs to be. If you think that the increased PE is because of just a night time feeding response, then do the experiments that I mentioned.

Also, what you posted from Levy is about one species of Caribbean coral, of which none of us have in our tanks and the whole point was to say that the axial and radial corallites have appear to have different behavior - notice how he did not mention that all acropora do this and they had more access to pacific acropora. The first part of the paragraph is about a broader range of corals when he lists the three uses of the polyps. Beyond this Caribbean coral mentioned, there is no evidence that axial and radial corallites act differently, according to this snipped from Levy et al., so specifying axial or radial is of no consequence to this discussions since nobody has any of these corals unless you run a public aquarium. I think that you mixed the first and second part of the snippet that you posted.

 

[C. Eymann]

You are missing it or appear to be seeing what you want to see...

Polyps are always used for gas exchange, sure. During the day, the polyps do not NEED to be out much since the zoox can help with gas exchange. They are out more at night since they NEED TO BE to breathe (bad choice of words).

Even though they do have to breathe all day, the PE is more at night because it needs to be. If you think that the increased PE is because of just a night time feeding response, then do the experiments that I mentioned.

Also, what you posted from Levy is about one species of Caribbean coral, of which none of us have in our tanks and the whole point was to say that the axial and radial corallites have appear to have different behavior - notice how he did not mention that all acropora do this and they had more access to pacific acropora. The first part of the paragraph is about a broader range of corals when he lists the three uses of the polyps. Beyond this Caribbean coral mentioned, there is no evidence that axial and radial corallites act differently, according to this snipped from Levy et al., so specifying axial or radial is of no consequence to this discussions since nobody has any of these corals unless you run a public aquarium. I think that you mixed the first and second part of the snippet that you posted.

I think it is you who are mistaken/confused, reas this again


"Tentacles of Symbiodinium-rich radial polyps throughout most of the colony are extended during
the day to capture light and remain extended at night, while axial polyps at the tip of the branch,
which contain few Symbiodinium, are retracted during the day and only extended at night for
feeding on active zooplankton."


The Caribbean coral is an Acropora, I do not believe their radular and axial corallites polyp behavior differs much, if at all to our Pacific dwelling acros.

 

[jda]

You are probably right... that is why a research scientist specified that one coral instead of saying that it applied to all of them. It was probably a detriment to his paper that they did not ask for your opinion and just studied the specimens.

If you don't want to believe it then don't. Something does not have to be true for you to believe in it. One day, when you see this somewhere else and get it, please have the decency to come back here and post about it.

 

[C. Eymann]

You are probably right... that is why a research scientist specified that one coral instead of saying that it applied to all of them. It was probably a detriment to his paper that they did not ask for your opinion and just studied the specimens.

If you don't want to believe it then don't. Something does not have to be true for you to believe in it. One day, when you see this somewhere else and get it, please have the decency to come back here and post about it.

I never said you were wrong?

I definitely agree that radial polyp behavior/extension and respiration/gas exchange are correlated in Acropora.

As far as nocturnal axial corallite polyp behavior/extension goes though, I believe the main purpose of them is food capture like the article I quoted states.


I'm not trying to step on toes, I generally agree with a lot of what you post on here, esp when it comes to SPS care and calcium reactor tuning, you know your stuff, and I think this debate we have been going on and on about in this thread is maybe due to confusion? maybe on both our parts?

Either way, I do appreciate your contributions and insight on here and other forums I have seen you on in the past, I am from the midwest as well and I think I have even seen you on a local midwest forum that is not around anymore unfortunately, very possible we have met in person as well, I'm originally from Kansas City.

 

[mzlskink]

Despite the passive aggressiveness and all (my personal opinion please I don't want to argue in this war either). I found this thread the most useful in discussing polyp extension, especially how choking off the gas exchange would cause polyps to extend.

I do feel like whenever I receive a new frag, it always has good polyp extension but it gets lesser over time in my tank. I used to think it was always a me problem, but then I do see decent radial PE daytime and axial PE evening - so maybe it isn't that bad in the end

 

[pygoplites77]

Sorry for my English.. I'm restarting this discussion hoping for an answer..
If PE (radial) was exclusively due to the need to breathe at night, why do I see so many aquariums with SPS in excellent health that have a notable PE even during the day? And why in my tank, as soon as I buy a SPS that in the shop had a large daytime PE, then in my tank, after 2 or 3 days, it has PE only at night? I don't feed the corals (which however grow and are colorful), while in the shop they are fed with a fish-based mush every day.. could it be that the coral extends the polyps to increase the contact surface to feed on the DOM? Logically I should deduce that it is so.. and this would not conflict with the theory of nocturnal gas exchange and not even with the theory of the axial corallite that extends at night because it tries to prey.
What do you think?