Lets Talk About Sexual Reproduction!!!!

[Mr.Firemouth]

Seriously!
I have been keeping zoas/palys for a long time. 20 years ago these were only known as button polyps and the majority were from the Caribbean as they came on what was then called Atlantic Shelf rock. This live rock was very large shelf like pieces that was extremely porous and light. They were usually covered in Eagle Eye type zoas. Because water parameters 20 years ago were a bit on the rich side, these zoas usually spread extremely fast and took over other stuff in the tank. Many considered them pest, so I was surprised at how they gained favor over the last 5 years as they are now one of the most popular corals to keep.

In the last 3 years, I have been deliberately trying to propagate zoas.(like many of you)
I have paid very close attention to what works and doesn't. One thing I have found out is that cutting the flesh of the polyp can trigger a new polyp to grow from the wound, yet this is a 50/50 event. So I kept looking and wondering why do they just explode in population sometimes and die off or stop reproducing after I frag them?

I believe I have found the answer but am not a scientist and can never validate what I have been seeing, but I will share this with all of you and see what you thoughts are. I tend to post on multiple forums redundantly for mixed opinions and to share observations, but this site is the Original Club-Zoa, so I will only post it here and link it at other sites.

I have been watching countless frags and colonies change population densities and wondered is it light, food, flow? Well yes to all 3, but that is only a natural cause as feeding, having a good ample light source, and a good flow of clean water is essential to success with all corals, but why do they sometimes explode in growth?

Here is what I think is the answer...SEXUAL REPRODUCTION.(of some sort)
Let me show you some pics as my tank is reproducing rapidly the last 2 weeks...
Pic 1, Alien Eye Zoas...

Does anyone notice anything strange or out of the ordinary? If not look to each polyp and compare.

You will see that some polyps are definitely larger.(I believe this to be a female polyp, but who am I to judge?) I call these large polyps the Mother polyps.

Now look at some of the other polyps that have their centers protruding. I believe that these are male polyps and that they are working with the female polyps to fertilize each other to produce "daughter polyps".

In every case for the last 1year this takes place and I see a rapid increase in the growth of a colony. Now here are some more pics also showing larger polyps and polyps with protruding centers....
Pic 2, Bam-Bams...

Pic 3, Unidentified zoas...

In all pics there has been rapid growth and the centers have been protruding, perhaps releasing chemicals or something I can not see that helps reproduction.
Now look at these 2 pics of very slow(or inactive) growers...
Pic 4, Unidentified zoas...

Pic 5, Whamin Watermelons...

In comparison these colonies have flat centers and are NOT protruding like the other zoas.
With that said, the zoas I have now will not be protruding next week either. I believe that after a growth explosion, they have a rest period before they become active again. I also believe that there must be a trigger that causes a colony to begin this, like a chemical release from 1 polyp or an environmental trigger like a drop in temp. This I have not been able to pinpoint.

So great, I have a theory that when my zoas are protruding they are sexually reproducing. So why do they all of a sudden die off or not regrow when I frag them and get rid of the polyps?

My guess here is that the large polyp is the Mother. If you frag the largest polyps and keep the small ones it takes for ever to get them growing again. I believe the large polyps are sexually active and therefore trigger more zoa production. Almost every time I have lost the largest polyp to a frag or trade I have had a recession in growth or I lose the colony.

This is not a lab tested theory, but my observations over the years. I an not prove anything but just show you pics and tell you what I see happening over long periods of time. I have taken zoas and fragged the large one to see what happens when I keep it on a plug with 2 protruding zoas. The result after a healing period of about 1 to 2 weeks is again an explosive growth were the colony triple in size in less than a month.

I hope you guys who are zoas diehards like me think about this and watch your tank for some of this activity. I would love to hear that you see this happening also. I have witnessed it in several different systems between here(St.louis) and Chicago, but again I am just looking and seeing this. I believe that many would not even notice, but I have been trying to figure this out. I got the idea from plants pollinating one another. It could be possible that something similar is happening here also.

What do you guys think?

 

[Hypertek99]

Hmm very interesting

 

[TyreeUM]

just my two sense from what I know about corals from a reef biology class I took from Dr. Bob Steneck and also from lectures at the Marine Ornamentals Conference in Hawaii-corals for the most part reproduce by a process known as broadcast spawning (which is the same way most bivalves spawn as well) which means the corals release both eggs and sperm into the water and when the eggs are fertilized they form a planktonic coral "baby" which after going through a few different stages settles itself on a suitable substrate and begins to grow at that point. This is called coral recruitment and is a way for corals to relocate their species to ensure survival in a sense. So unless you have new polyps springing up in odd places away from your main colony I would have to assume that they are still all connected and just "spreading" which is asexual reproduction.

 

[flricordia]

Zoanthids reproduce asexually unlike many corals and though zoanthids belong to the same kingdom as stonies and softies, they are not corals but sea anemonies/colonial anemones. No males or females. They do not fertilize each other. But if you were to assign a gender to them it would probably be female since they produce duplicate clones (which does not parallel color. color variations in same zoanthid types depend on amount of proteins and xoothanthellae in each polyp dependant on factors such as lighting).
A colony of zoanthids is really one living organism since they are all connected. In all reality, only one needs to feed which will feed all the others in the colony.
In turn there would be no need to have 2 genders since they are all connected. Some do grow faster than others and even then at different times depending on water parameters, temperature, lighting, etc.
All zoanthids will multipy when fragged much faster than if they were left to their own. That is if they are fragged successfully.
It is a cool theory though, what you have stated.
Zoanthids are known to produce buds that never complete growth and eventually break-away from the main colony to resettle elsewhere sprouting into a new colony. Some complete polyps also can detach and settle in a new location to start a new colony. Radioactive dragon eyes, eagle eyes, many morphs of zoanthus do this often, even in captive systems.

 

[TyreeUM]

actual zoanthids can and do sexually reproduce in the wild...they like a lot of other cnidarians have sexual reproduction that is triggered by moon phases among other things. That being said there are both "male" and "female" zoanthids...
http://md1.csa.com/partners/viewrec...lythoa+sexual+reproduction&uid=&setcookie=yes

 

[TyreeUM]

oh and by the way Mr. Firemouth im not trying to discourage or attack you in any way-i think the main thing I have heard over and over from so many different coral and reef biologists is how much we really DON'T know about coral and the living reefs-I wish there were more discussions like this than how much you can get for a certain frag...

 

[flricordia]

actual zoanthids can and do sexually reproduce in the wild...they like a lot of other cnidarians have sexual reproduction that is triggered by moon phases. That being said there are both "male" and "female" zoanthids...
http://md1.csa.com/partners/viewrec...lythoa+sexual+reproduction&uid=&setcookie=yes

I think there are other studies that might not agree with that article. Just because you find something on the internet you shouldn't always take it to heart.
I do recall reading something like that, but it didn't have to do wiht zoanthus, palythoa or protopalythoa and I don't believe parazoanthus was among them. There are they yellow polyps and some others that have been grouped with zoanthids that little is known about.
Doesn't mean I am right either, but studies done with zoanthus have never shown them to spawn on the reef. If there has been evidence to support it it would be nice to see others document it also.

 

[TyreeUM]

what studies? Palythoa/Zoanthus larvae are found in the water column all the time around reef areas...

 

[Mr.Firemouth]

Not being trained in the biology of zoanthids, I am unsure what terms to use, but I find it odd that you will see the "bud" polyp settle elsewhere. It is weird how that happens. Look at pic 4. You can see 3 different color morphs of zoas and you can clearly see 1 polyp by itself.

How much of the way that plants reproduce in fields could be used in my theory of zoas reproducing? (Maybe nothing.)

However, there is something definitely happening when there is these polyps protruding. There is no doubt a difference in population density.

I think the responses so far also help illustrate how much we do and do not know or understand about these animals.(Especially the color variants)

 

[flricordia]

what studies? Palythoa/Zoanthus larvae are found in the water column all the time around reef areas...

Cool. Where is that? Would love to read on it.

 

[TyreeUM]

I think that mouth protrusion is interesting as well have you forced the polyps to close and see if the different color morphs are physically attached? I have always thought that the differences in color expression in zoanthids of the same species is a good indication of sexual reproduction, when colonies that are asexual express the same color variant

 

[TyreeUM]

Cool. Where is that? Would love to read on it.

Alot of planktonic studies list palythoa and zoanthus species, here is one abstract...

http://md1.csa.com/partners/viewrec...2048&q=planktonic+palythoa&uid=&setcookie=yes

Here is an interesting article that points out that because of the high cost of sexual reproduction, it has been observed to be avoided by smaller zoanthid colonies.
Side note this article points out another interesting observation that in zoanthid colonies, there seem to be certain polyps that are the main polyps of the colony-and if somthing happens to one of them, often the entire fragment will be lost...

 

[Kigs!]

Is it possible that the "protruding" factor is an isolated case based on your tank environment? Leading it to be not an indicative clue as to identifying their gender but more of a direct result of your aquarium parameters. I feel skeptical about supporting this theory that's purely based on physical attributes of an animal. But then again, I never viewed my successful zoanthid colonies with the thought of sexual reproduction behind it. Very cool idea, I'll observe my colonies to see if any of my observations match yours.

 

[er1c.the.reefer]

i do believe that there are "main" polyps. these main polyps tend to be the mature, larger polyps. that's why i don't like fragging small, immature polyps; they either don't make it or they take longer to recover and mature.

furthermore, i've noticed that zoanthids tend to grow and die off almost as if seasonally. i notice faster growth in spring and summer months but come fall i can basically expect a die off on some of my colonies. reason behind this? i'm not really sure, but my guess it that it has to do with temperature (warmer water, higher metabolism, etc.) and other factors we can't see like barometric pressure. for example, i remember when i used to breed betta fish as a teenager that i could pretty much count on them breeding a few days before it rained. animals can "feel" things we can't.

another one of my thoughts is that because we maintain our temperatures and lighting pretty much constantly the same year around, we aren't providing the seasonal variations that would be provided for in the wild. for example, if you maintain your tank at 80*F year around, you may be putting your colonies in a state of continous growth. without a seasonal drop in temperature, there's no rest or hibernation period, your zoas are undergoing a constant rate of higher metabolism, may build up free radicals quicker, and can become stressed more easily.

i don't know if what i just typed made any sense. i'm just procrastinating from studying right now.

 

[Mr.Firemouth]

I cycle in 1 dark day a month where I kill the lights for 24hrs, I believe it helps with color.
I also do not use a heater or chiller but regulate the tank with room temps, so my tank can go anywhere from 74*F to 82*F within a given month.

Kigs, I have seen this in other hobbyists tanks, but only lately have I been really believing that the "protruding" discs may be responsible for explosive growth patterns.
At one time I thought this was caused by too much light, but see it now in dimmer areas of the tank as well.(over production of photosynthesis)

I think that when we frag we should be selective about the polyps we take/separate to make the frag and the colony successful.

I like that there has been articles about the "main" polyp theory as well.

 

[TyreeUM]

great discussion - I think one thing is pretty clear about zoanthids in the wild, it's that they don't become sexually reproductive until one or a certain combination of natural cues triggers them, whether it be temperature, photoperiod, or tidal phase or whatever, which is why we hardly ever experience sexual reproduction in our tanks. In fact I have read articles by people who have done cross sections of wild polyps at different times of the year and the zoanthids during say the summer periods do not even contain any products needed for sexual reproduction. SPS in the wild for instance have incredible spawning events that take place at certain times of the year, one begins to release gametes into the water which triggers all the colonies in the area to start releasing-it's pretty incredible, but I would imagine zoanthids would do the same thing.

 

[revhtree]

Great thread! I am tagging along!

 

[TyreeUM]

I used to look at water samples of my tanks in our lab back when I was in school and the diversity of "plankton" wasn't that incredible in any of my closed systems anyhow, but with the huge amount of filtration in our systems it seems probable that any amount of gametes from broadcast spawn of corals would be filtered out before we even woke up in the morning. That being said, in the 1,500 gallon tank I set up a pelagic egg collector and every night found thousands of fertilized yellow tang eggs from that system with no lunar lights present on the tank (there was a small group of 7 yellows in that tank)-so who knows with zoanthids or any other coral in our systems how often if at all they do spawn...

 

[Azurel]

The main polyp idea is one reason why over the last few years I quite trading or selling single polyps of Purple Deaths of Nuclear Greens. I found that when I fragged a single polyp large or small it would often die, but if I fragged a large polyp and a small polyp(connected) within days of the first week or so of healing I would notice a new polyp starting to form. With in the first month after fragging I would have that 2 polyp frag up to 4-5 polyps. I also fed but there are guys on here that can attest to the speed of which I could get those particular polyps(morphs) to spread by not fragging single polyps. The single polyps if I had one survive would take twice if not longer to show any signs of spreading. So I really would have to agree on the main polyp idea.....Great discussion. I used to talk to James Reimer quite a bit back in the early days of Club-zoa and had all of his research that he had on Zoanthids and Palythoas. Some of it was quite over my head but I think to really get the gist of zoanthids and palys it is going to come from the hobbyist side of the research. As they are not that important in the ladder of things that need research it seems....

 

[TyreeUM]

haha your so right on the research, I think you will have a hard time finding a whole lot of research done on zoanthids in the wild much after 1990. Everything now seems to be focused on reef building corals, but rightfully so I guess...