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Anonymous

Guest
Hi all

One of lifes great mysteries

Why does it do this, I have heard it is to

1.Capture prey.
2.Respire.

I noticed when raising the ALK/P.H of my tank a while back that it suddenly started to do so.

Why, does water with a higher PH carry less oxygen, necessitating a pulsing action to be adopted by the xenia to respire.

There seems to be a definite link between PH levell and pulsing or non pulsing of xenia.

That would then discount the feeding theory.


mmmmmm interesting.


Cheers


Brian.
smile.gif
 
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Anonymous

Guest
I have read that Xenia is thought to pulse for gas exchange. If I can find that article I bookmarked, I will email it to you or paste it here if it small enough. Xenia do not have nematocysts to capture prey, like an anemone. Mine never close onto floating particles either, even small things like 50 micron size rotifers.
 
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Anonymous

Guest
They do not pulse to capture prey, and xenia have been known to pulse better and faster with a pH of 8.3 or higher. IMO they are pulsing to keep them moving to remove that microlayer of stagnant water on them for a couple of reasons:

1) when they are subjected to good water motion they do not pulse frequently.

2) When there is little water motion they pulse like crazy.

3) When they ship they usually die because all the water is stagnant, not just the microlayer around them. The stagant water would let the bacteria that kill it thrive and multiply, that is why some people apply Lugols solution directly over the xenia, to kill that bacteria.

But thats just MO.
 
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Anonymous

Guest
My xenia pulse at night. They shrink their stalk down and are not extended very far but the head actually pulses after all the lights go out. Also, I thought that xenia died during shipping because the slime they put out raised bacteria levels in the water in the bag which in turn used up all the oxygen..........RR
 
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Anonymous

Guest
My Xenia extends and pulses like crazy until about 8pm, then retracts. Is it tired? I have 6 frags and the largest frag on the left side of the tank starts retracting followed across the tank until the one on the right retracts too. Weird.

------------------
Jim - GO HOGS GO!

My Reef Page
 
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Anonymous

Guest
Monkeyboy, our xenia is in various flows around the tank, and the stuff in high flow is pulsing just as much as the stuff with very little flow.

Respire is the most commone explanation that I hear. Another interesting theory (and this may answer your ? fischievious) is that when they pulse it lets the expose different parts of the polyp to the light, so they are able to maximize the use of all of their surface area, as opposed to only using the side facing the light. I'm not sure if it's true, but it seems plausible. And I have noticed that our xenia pulses a little more at night when the 'moonlight' is on.

Another reason that it may stop pulsing at night is the drop in pH. Most won't pulse if the pH is below 8.1 for a while. Many tanks may drop below this at night, so that could stop the pulsing. Then, in the morning, when it comes back up, they start pusling again.

Brian, it's good to keep that pH up, since the xenia seems much less prone to crashing if the pH is up and it's pulsing.

Best fishes, I'm wondering if maybe your pH is too low. That would be the first guess as to why the xenia isn't pulsing. Also, there are some corals that look a lot like xenia, but don't pulse. If you had one of these, that could be the problem (LFS mislabel things all the time, so you can't really assume it's xenia just because they said so).

Dave

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http://members.xoom.com/lcrandall/reefpage.html
 
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Anonymous

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fishchevious: I have no clue, but i do think that we are all wrong. It's probably for some purpose that know one will guess in a million years. everybody has their own theory.
 
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Anonymous

Guest
Brian, You Da Man! Look, as far as I have seen, Xenia does what the bloody hell it wants to. My Elongata pulses when the lights are on, off, high or low current, alk level at 7dkh or 10dkh. It shrinks up twice a day, once at about noon and again at lights off, but only for about 10 minutes. Xenia is one of the wonderful mysteries that we enjoy....

Have a Guiness and drop me an E-mail sometime.

Fred

[This message has been edited by Hodad (edited 22 May 2000).]
 
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Anonymous

Guest
A guy at our annual conference gave a talk on that very question. I got little out of the talk, other than that xenia do not do it to catch/eat, but I believe his theory was that it pulses to keep foreign matter away from itself. He had a bunch of stuff, which I didnt pay much attention to, but I believe that was one of his major theories as to why it pulses.
 
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Anonymous

Guest
Hey monkey boy if they only stop pulsing when there is good water current than how come they pulse like crazy when the lights are on and then stop when the lights go off under the same current? (dont take this as a jab please, just curious)

[This message has been edited by fishchevious (edited 22 May 2000).]
 

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