Why does xenia pulse

Well a few years ago I had a that was lit by PC's yeah, I know lol and when I switched to de watt metal halides, the xenia exploded in growth. They went from loooooooong stringy stalks trying to reach the light, to thick stalks with tons of hands that split and split and split. So from my personal experience and that of the lfs I bought it from who also had it under mh's and had the biggest colony I've ever seen I'll say that they DO do 'better' under mh's.

That's NOT to say that they can't grow under different lighting, T5 etc. As I said, I had some under pc's And if the pulsing action IS the Xenia feeding, I've never seen it personally, never read that this is what it's doing, and never seen proof of any kind that this is what is going on. I've actually read the opposite Xenia is in no way catching food with it's 'waving hand' and bringing it into it's mouth. Thanks guys for all the info! I have the xenia under a w HQI, but it does have some flow around it, so I will try moving them to a lower current area.

The tank has a high ALK and good water quality, Maybe to clean for them. Some one told me about the iodine idea, but i use lugols and dont think thats the issue. Thanks again. I would guess it is just acclimating to the new tank. When I frag mine, they stop pulsing for a day or so. Originally Posted by thegrun. Sorry for a newb question but xenia's shrink when the lights are off, correct? I had my xenia for a couple weeks now and every night they shrivel up.

Ok I'm gunna say this much. I've had xenia in several different tanks. When under my pc lights they didn't pulse nearly as much as when under my halides. Also I have some getting blown around pretty decent from a power head and they still pulse really well. I know this doesn't help much combined with all the other info but just figured I'd put in my experience.

There are many species of Xenia with many different colors such as white, pink, brown and cream colored. Lighting is important with Xenia. They get most of the nutrients they need via the photosynthesis in their zooxanthellae. They will also feed on the dissolved nutrients in your tank and actually seem to do even better in tanks with higher than normal dissolved nutrients. If you keep these corals in tanks with lower lighting levels you may need to place them in the upper half of the tank.

There are many theories out there regarding the pulsing action of the Pulsing Xenia. Whatever the reasoning is, they are neat to watch. Slower flowing water usually provides better pulse rates. One thing you don't want to do is keep a steady blast of current on them with the power head. They may fail to open their polyps and stay retracted. The good thing to know is that just because it's not pulsing doesn't necessarily mean that they are on the decline health wise.

You'll usually read that natural seawater levels of iodine 0. In strongly coordinated pulsing, the contraction movement is much stronger than the movement of the relaxation extension, and this results in a net efflux of water through the colony. In other words, water is drawn from around the colony, through the colony, and outwards from the center of the colony. This has been hypothesized to be related to the facilitation of dissolved nutrient uptake.

It also correlates well with anecdotal observations of many Xeniids that display a coordinated and strong pulsing in nutrient poor tanks and a cessation of pulsing in high nutrient tanks. Of course, there are exceptions, as Anthony mentions in the article.

Additionally, pulsatility has been found to be affected by a number of other factors. This is a coordinated neuromuscular response, and the pulsing can vary from single pinnule bending or flexing, to isolated uncoordinated pulsing, to rhythmic, coordinated, forceful, colony-wide pulsing. The behavior requires ATP, a cellular energy source, and without adequate energy, pulsing cannot occur or may occur in a less vigorous manner.

Furthermore, the effects of various agents on pulsing has been demonstrated rather comprehensively in Red Sea Xeniids almost fifty years ago by H. Gohar in laboratory experiments in Ghardaqa, Egypt. He used a variety or stimuli, including electricity, drugs, temperature, and chemicals to determine their effect on pulsatility.

He found that some stimulated and some inhibited pulsatility, as might be expected from a neuromuscular response. Interestingly, in light of Anthony's discussion of temperature, is that coordinated pulsing took place in a range of temperatures, with the extremes of the temperature treatments both hot and cold causing inhibition or cessation. Likewise, I think many of the anecdotal observations in various tanks relate to any number of these type factors.

Pulsatility is not determined or controlled by one factor, but can be affected by many factors, some of which may or may not be the case in individual aquariums. Gohar, H. Roushdy Borneman, Eric, "Aquarium Corals," T. One of the attractive white Xeniids known as "pom-pom" Xenia , or " Xenia umbellata ," this variety can be adaptable but fares best under moderate to bright illumination with slow acclimatization.

Photo courtesy of Greg Rothschild. Untold numbers of unfamiliar Xeniids enter the trade as incidentals found on live rock or collected with other reef invertebrates. With some basic lab tools and techniques, you may be able to identify such guests with help from a good scientific reference like Fabricius and Alderslade's, Soft Corals and Sea Fans Photo courtesy of Skip Attix. Photo courtesy of James Fatherree.

This wonderful variety is attractive, weakly aggressive and easily controlled. When allowed to grow into great patches, it makes a stunning impression with the action of its swaying tentacles. Photos courtesy of James Fatherree. Could this be Sansibia? Many odd little soft corals are acquired as incidental growths on rock and with other collected invertebrates.

Wishful aquarists like myself retreat to the scientific and hobby literature to try to find a name for such surprise guests. Identification by image alone, however, is impractical and unrealistic for most any coral - to the genus level, let alone species. I think I can hear my dear friend Eric Borneman weeping in a corner as I declare that this must be Sansibia because I just bought a new book with a picture that looks just like it!

And for our next trick, lets rename all of the Acroporids in our tanks because Charlie Veron came out with a new book series, shall we? This attractive and fast-pulsing Xennid is commonly called "Silver-tip" or "Blue" Xenia for its magnificent tendency to brighten with strong blue-green color when kept under cool colored lamps k Kelvin.

Even this tiny fragment of Cespitularia has begun to show its telltale irridescent glimmer as light is reflected off of tiny sclerites. With strong VHO blue or 20k Kelvin Radium lamps, for example, they often turn a stunning solid blue color - hence the legendary name "Blue Xenia. Photos courtesy of Eric Borneman. Courtesy of Joseph Weatherson.

One of the most amazing things about most Xeniids is their remarkable range of reproductive strategies. A new colony can be formed from fragments as small as a single pinnule! Infected Xenia with necrotic stalks and captitulums "crowns" can still be salvaged by snipping off tentacles, and even the feathery pinnules, to start new colonies elsewhere. Photo courtesy of Amy Larsan Tippytoex. Photo courtesy of Graham Gregorich. If you have any questions about this article, please visit Anthony's author forum on Reef Central.

All corals were returned back to their original location after the experiment terminated. Corals are among the most ancient creatures surviving on our planet. The symbiotic algae provides the coral with essential nutrients and lives off the waste of the coral. In a previous study of the same research team which the results of were also published in PNAS it was found that the motion of water around corals is essential in order to enhance the efflux of oxygen from the coral tissues.

Without water motion, the oxygen concentration in the coral tissues would rise and the photosynthesis rate would drop. The answer to the question as to why the Heteroxenia pulsates was finally revealed through the lab experiments.

First, the photosynthesis rate of a pulsating Heteroxenia was measured, and it was found to be on an order of magnitude higher than that of a non-pulsating colony. Next, in order to prove that the mechanism of pulsation is intended to sweep away oxygen, the researchers artificially increased the oxygen concentration in the measurement chamber so that even when the coral managed to mix water via pulsation, it was replacing oxygen-rich water with new water, which, unfortunately for the coral , was also rich in oxygen.

And indeed it was found that the photosynthesis rate was low in this case, and even when the coral was constantly pulsating, the oxygen concentration remained high and photosynthesis remained low, as if the coral was at rest i.

The elegant motion of Heteroxenia has been fascinating the scientific society and capturing the attention of researchers for nearly years Jean-Baptiste Lamarck, , yet it has not been explained.

Now, in the study of Kremien, Genin and Shavit, it was found that the pulsation motions augment a significant enhancement in the binding of carbon dioxide to the photosynthetic enzyme RuBisCo, also leading to a decrease in photorespiration. This explanation justifies the investment of energy in pulsation — the benefit overcomes the cost. In fact, thanks to pulsation, the ratio between photosynthesis to respiration in Heteroxenia is the highest ever measured in stony and non-pulsating soft corals.

The findings of this study indicate that pulsation motions are a highly efficient means for sweeping away water from the pulsating body, and for an increased mixing of dissolved matter between the body and the surrounding medium.

These two processes expulsion of medium and mixing of solutes may lead to future applications in engineering and medicine.