Giganteas tracked by aerial photos

[Dan]

"...One actinia in the rock beds was actually found to have divided into three...." (ref. pp 421).

While true they did not witness the split, circumstantial evidence seems to suggest it. One might, therefore, speculate that they may be split artificially. Ok. Who's first? Seriously, I am sure the first attempts at splitting BTA ended in failure, and probably still ends badly for many BTAs. But enough are being produced now to supply a large portion of the demand. It is just a matter of someone with access to many gigs figuring out the best method(s).

Regarding the distribution, I think that it is completely dependant on currents. Anemones in the patch reefs are going to be somewhat sheltered by the more stable structures, allowing them to get a tighter grip on the substrate over time. We see that in our own tanks. The more time an anemone is stable in one place, the tighter the grip becomes. The gigs in the sandy bottoms are in less stable, i.e., movable, environments. So currents can more easily remove them from the study area (or into the patch reefs). Also, tightly gripped anemones are feeding anemones, so they will be larger in the patch reefs.

Dan

 

[Gary Majchrzak]

heck

heck

I wish that we could locate someone that had a gigantea bud survive!

 

[kduen]

"... It is just a matter of someone with access to many gigs figuring out the best method(s).



Dan

If you search around on this site long enough you will not find one thread that has a successful manual split of a Gigantea. There are some with the claim that they have but after about a month or so they drop off and are never heard from again. There is only one that I know of that documented the entire thing and that was Phender with his Mertensii and still after 12 months both halves were dead. There are a lot of claims of success but no actual proof to back up their "story".

 

[elegance coral]

"Giant sea anemones can reproduce sexually and asexually
(Dunn 1981; Fautin and Allen 1992)"

The above is a quote taken from the paper. Fautin and Allen 1992 does not support the statement that giant sea anemones reproduce asexually. I have a problem with any paper when the researchers don't even read their own references. I may still trust the FACTS of the paper, but any conclusions drawn from those facts are questionable, at best, IMHO.

The researchers obviously believe these anemones are capable of asexual reproduction. With this belief, they see something that's a little out of the norm, so they assume asexual reproduction has taken place. They presented no evidence to substantiate this assumption. Were there obvious wounds on these smaller anemones from have been recently divided????? Were the mouths off center????? Did they do any genetic testing?????

To me, this is like having someone that believes we are being visited by aliens, do research on lights in the night sky. The moment they see something they can explain, they will conclude that it's a ship from outer space. In reality, there's probably a much more logical explanation, that's simply being overlooked by the researcher.

 

[BonsaiNut]

The researchers obviously believe these anemones are capable of asexual reproduction. With this belief, they see something that's a little out of the norm, so they assume asexual reproduction has taken place.

In the very paper referenced at the beginning of this thread, the researchers tracked giganteas within the study area over three years. In a single instance, they returned to one coral outcropping and found three anemones in close proximity to one another, where previously only one had been. They somehow decided that the single anemone had split into three individuals in the course of a year. No evidence was given to support this claim (aside from the three individuals being smaller than the one individual that had been there before), and I have yet to hear back from the author of the paper when I wrote to ask for more information.

Certainly if it happens at all, it is very uncommon. The same could also be said of H. crispa and M. doreensis - millions sold into aquariums and not a single recorded incidence of asexual reproduction. It is hard to believe that any of these species relies on asexual reproduction to maintain species numbers if asexual reproduction rates are so low while numbers of individuals in the wild are so high.

In the case of this paper - gigantea field study in the wild covering approximately 44 individuals over three years - there was a single recorded case of possible asexual reproduction. At the same time, nine anemones "disappeared" and six new individuals were "found". Assuming that the study was 100% accurate, the new individuals had to have been from sexual reproduction since they appeared in new locations that were distant from other individuals. Therefore the rate of asexual reproduction - of about 2% per year (two new individuals out of a population of 44 over three years) - did not come close to matching the rate of disappearance and assumed death. Compare this to the asexual rates of H. magnifica and E. quadricolor - both of which reproduce both asexually AND sexually. Their asexual reproduction rates are so high that in some locations they are considered pests and colonies cover an acre or more of reef.

 

[Reefahholic]

That's crazy...

 

[trueblackpercula]

Ya no this thread is three years old right Lol

 

[Breadman03]

Glad to have seen this!

 

[SDguy]

That's crazy...

 

[DasCamel]

Interesting thread still.

 

[D-Nak]

I agree-- thanks for digging this one up. I missed it the first time around.

And... if anyone is thinking about cutting their gig after reading this thread, please don't. :deadhorse1:

 

[adtravels]

I have been lucky enough to snorkel and dive all over asia, I have seen 100s of gigantas from thailand to the red sea and borneo. ALL have been in water that I could have stood up in at low tide and in rocky rubble areas sometimes near seagrass but mostly not. Whilst diving in these same waters I have NEVeR seen one. So I wholly agree with the findings of the paper. They are locally quite abundant near me in the gulf of Thailand, I see mainly a peachy pink one all around Ko Samet here and have even seen a purple specimen that I have visited a few times. But they are only locally abundant so uncer threat from costal development. In mabul near sipidan they were on the inner reef frght next to the resort and boat peir here they were tan, blue and green.

 

[phender]

After reading the abstract to this article again I have to wonder how good the researchers were at differentiating between S. gigantea and S. haddoni.

Sandy areas at the fringes of grass beds sounds more like S. haddoni habitat than gigantea habitat. It wouldn't be the first time I have seen these anemones mis-IDed by people who you would assume knew the difference.

That being said, there is certainly no doubt that their shallow water habitats are vulnerable to human activities.

 

[OrionN]

I am glad that I seen this thread also. Missed it the first time around.