Forums / TEAM Marine Depot / Invertebrates; Morphology, Ecology, and Behavior – by Dr. Ron Shimek / BTA reproduction / Latest Posts

RE: BTA reproduction

magellan007 — Mon, 05 May 2008 09:03:13 GMT

Don't get me wrong; I DO have algae, but I've just never experienced an "outbreak" like many others have--others that keep their tanks at 76º and 78º, which I think is too cold for daytime temps. I have every type of algae present in my tank--I managed to get rid of the bubble algae which I acquired with the rock my anemone was attached to--and I almost had a hair algae outbreak, but I have plenty of little critters who munch on it and keep it "mowed down" to a tolerable level. The flow from my wavemaker also makes it difficult for the algae to attach and spread too much.

And I'd rather my anemone not "spermate" my tank since I've yet to set up my new sump & skimmer, lol. I don't want to get another anemone--unless it's a rock anemone, they're so pretty--because I have a hard enough time with my rbta growing to a gargantuan size in a relatively short time. It makes me think it's about to split again when it puffs up and extends its base during the night, but then during the day it stretches considerably towards the top of the tank. (and I have sufficient lighting, and I feed it once or twice a week, so I don't know what it's doing) But It looks really happy.

RE: BTA reproduction

Ron Shimek — Mon, 05 May 2008 08:35:13 GMT

Hi,

No, remember the truism: "Absence of evidence is not evidence of absence."

You won't see any gametes if the animal is not in good condition or has been subject to the wrong environmental conditions (such as, I suspect, an environment that it too stable to trigger gamete development). In these cases, it won't make gametes (either eggs or sperm). And you won't see eggs.

There are three ways to determine gender:

1) Watch the animal spawn.

2) Externally examine the "gonads" and see their development.

3) Do a microscopic biopsy of the gonads and examine the cells.

I suggest you boost the temperature a few degrees on either end of that range. You might get algal growth, though; I suspect your temperature is simply too cold for algal (and reef animal) growth during a large part of the time. In the real world these creatures would likely never see any temperature that low.

RE: BTA reproduction

magellan007 — Mon, 05 May 2008 08:31:48 GMT

gah.. i posted before i saw there was a "page 2". I think I have a male then..I'll look more closely tonight.
I FINALLY got a new temperature thingy for the tank. And I observed that during the day my tank temp is at 82ºF and at night it falls to 74ºF. Everything loves it and though you might think it, i do not have a lot of algae growth.

RE: BTA reproduction

magellan007 — Mon, 05 May 2008 08:26:28 GMT

so, if you don't see eggs, does that mean there's a very good chance you have a male? are there any other ways to tell the sex?

RE: BTA reproduction

greenbean36191 — Sun, 04 May 2008 09:51:36 GMT

Like Ron said, ecological and environmental data for Entacmaea is hard to come by. When it comes to taxonomy and bioinformatics, Fautin is the one to go to, but for ecology of this species Nanette Chadwick (Fautin's academic sister) is the authority. Still, even from her work you still can't answer all of your questions. The good news is that within the next 2 or 3 months, the body of knowledge about this species is going to increase dramatically and even more so over the next 3 or more years, though I'm not sure how much of that will make it to publication.

Probably the best references (so far) to answer your questions about their habitat are:
Richardson, D.L., V.J. Harriott & P.L. Harrison. 1997a. Distribution and abundance of giant sea-anemones (Actiniaria) in sub-tropical Eastern Australian waters. Mar. Freshw. Res. 48: 59–66.

Chadwick, N.E.; Arvedlund, M. (2005). Abundance of giant sea anemones and patterns of association with anemonefish in the northern Red Sea. J. Mar. Biol. ***. U.K. 85(5): 1287-1292.

The basic trends are that they're most abundant in 0-10m but only slightly less from 10-20. After that the numbers drop off pretty sharply. They also tend to prefer protected sites, though the amount of wave energy wasn't measured quantitatively. They're also more common on patch reefs with lots of crevices than reef slopes with lots of coral cover. That may be due to environmental differences or just a lack of available space.

RE: BTA reproduction

Ron Shimek — Sun, 04 May 2008 07:07:04 GMT

Hi,

They will definitely spawn with only one gender around.

As I said, I can't tell the sex of the individual from that image. If I was there, I could have, but long distance, nope.

I have been telling hobbysist for several years that good and proper care for all their reef animals includes normal variatons in temperature and lighting. Given those, the animals will spawn. If you want to mimic spawning in nature rather neatly, you can do it including all cues. That will ensure spawns, but without any cues - no spawns. In the cases of most hobbyists, the animals are in an "endless winter" with the temperatures kept too cool (below about 82F) and with no variability. In these cases, they will put excess energy into cloning.

Asexual reproduction is all well and good, and it is certainly better than nothing, but...

We won't be able breed for hardiness, or specific colors, or other attributes untl we can sexually reproduce the animals. Given that reefs are doomed, it would be "nice" to have a leg up on domesticating these creatures before we run totally out of pospective brood stock.

RE: BTA reproduction

Reefski — Sun, 04 May 2008 06:03:38 GMT

will they spawn with only one sex in the tank? i started with only one about 18 months ago that has split on it's own such that i now have 14 animals.

i haven't seen any spawning. could you tell the sex from the picture?

you said they should be spawning if well taken care of but earlier in the thread you were talking about very specific cues that were needed to trigger spawning. i am confused.

RE: BTA reproduction

Ron Shimek — Sun, 04 May 2008 05:54:25 GMT

Hi Carl,

Your image shows a septum protruding from the mouth of the animal. It may show a gonad - or not - depending up on the physiological condition of the animal.

I think any aquarist who has had these animals for any length of time and has not had a spawning is not properly caring for them. It indicates a lack of proper food or a lack of proper environmental conditions or both.

RE: BTA reproduction

Reefski — Sun, 04 May 2008 05:34:58 GMT

Ron:

are these gonads seen in this photo?

if one could get them to spawn then what? what do you feed baby anemones? how much water system and filtration system would one need? wouldn't a spawn overwhelm most any tanks support systems?

Joe at Atlantis Marine World in New York has a 2000 gallon RBTA display. he told me he has not had a spawning in his tanks and is happy about that.

RE: BTA reproduction

Ron Shimek — Sat, 03 May 2008 13:11:45 GMT

Hi Mark,

To mimic tidal events, you will need to find out typical tidal currents in some of the areas where these animals are found. This information is often available in governementally produced tidal tables for port areas in the region. Tidal currents vary a lot in various places both in the pattern and in the magnitude. As an example, it is sometimes considered common folk knowledge that tidal currents in many atolls are minimal, and it is true- some times and for some atolls. Yet, I was once caught in an ebb tide on Palau that quite literally rolled 1 meter diameter pieces of tabulate acroporids along the bottom and flung Diadema through the water about 2 m above the bottom rather like the echinoderm equivalent of dandilion blossoms.

Anyway, you can set up pumps to move water in typical tidal patterns, whether or not the tides are diurnal or semi-diurnal, or some other tidal pattern. Basically this is oscillatory flow with a 12 or 6 hour period of fluctuation. Then you have to consider that the magnitude of the flow will vary significantly. As an example in one of my long-ago research areas, at the spring tides, the maximum currents were about 9 knots. At the neaps, about 2 knots. Finally, you have to consider that the high and low tides differ from day to day in their times. As a rule of thumb, any given high or low tide will be about 50 minutes later on a subsequent day. So, if the maximum flood current is at noon one day, it will be at 1250 the next, and 1340 the following and so on.

Tidal currents by themselves can be an indicator of season. In the Pacific NW of the US, the maxium high tides are around mid-day in summer, but are about midnight in winter, and during the spring and fall equinoxes, there are very minimal tidal exchanges for periods of about 14 days. So... if the organism can sense changes in day length and sense tidal currents, they can "know" physiologically what day it is to within a 3-5 day window of precision, at any time of the year. If they have a physiological trigger that works on increasing day length and, say, decreasing tidal flux (current flow over the animal), the animal is aware when it is spring, and when it is the equinox and both are good markers for spawning to take advantage of the spring plankton bloom. If the organisms can sense temperature - that provides one more marker and a "reliabilty" check that it is a good time to spawn.

Now - how do they sense things... Hard to know (not much research) but consider... For animals with symbiotic zooxanthellae, as the days increase in lenght the amount of sugars produced increase. If the physiological trigger is a certain sugar level, it is easy to see how that could be sensed. With regarding temperatute - all of the animal's physiology is cued to temperature and a 5 degree C temperature rise in the average ambient temperature increases a typical reef animal's metabolism by 50 percent! So, if spawning occurs when a given hormone concentration rises to a given level, then as the temperature goes up, the hormone concentration rises right along with it, and can be a very precise way of "getting ready," especially if the hormone is triggering maturation of the gametes. Finally, current flows over the animal can alter water concentrations of, say, oxygen or carbon dioxide and a sudden drop in, for example, carbon dioxide after a prolonged rise (a pattern which would occur if there was a period of neap tides with little current followed by a some stronger currents that pass a threshold level) could easily trigger a spawning event.

As regards images and various anemones... First, the various host anemones are taxonomically different creatures with quite different environments. Don't make the mistake of considering that what is good for one as being good for another. That is not the case.

Additionally, as regards images. These DO NOT provide unbiased samples or indications of where the animals are found. They do provide information about what a given photographer wanted to take an image of at the given moment. I have found S. haddoni in quite shallow waters. At the same time, and in the same areas, I found them as deep as I wanted to dive; at that area it was a depth of about 50 m. It would take a lot of transect work to even begin to guess what depth range they prefer. Most of the published information on these animals has been written by taxonomists such as Daphne Fautin. She is a great taxonomist and scientist, but she isn't an ecologist, and particularly when she was doing her host anemone work, she didn't ask "ecological" questions or sample in a manner that gave the answers to those questions.

It will be difficult to get any real data about distributions with regard to these creatures. I know - I have looked.

RE: BTA reproduction

Mark — Sat, 03 May 2008 11:56:43 GMT

Hi Ron,

Thanks for the info on the effect of waves... I was being a little careless with my terminology. Let me rephrase my question. You said:

...spawnings are cued by a combination of events - temperature changes, day length changes, and tidal events.

I understand how to provide temperature changes and how to simulate day length changes. What would you suggest I do to simulate tidal events?

BTW, I definitely plan to get your AHABS articles. I'm currently working my way through Shick's A Functional Biology of Sea Anemones. It's a very good book but specific references to the anemones I'm most interested in --E. quadricolor and S. haddoni-- are rather sparse.

The information I'm having the hardest time finding is detailed information about the conditions where these anemones live. I've collected about 100 images of S. haddoni anemones in the wild, many of them exposed or in very shallow water when the tide is out, so I'm confident they are routinely exposed to waves/surges/tides. I have much less information about the natural conditions where E. quadricolor anemones live, mostly just short videos. Since it's difficult to glean much about flow from a video or two, I'm mostly relying on my observations of these anemones over the last several years... and that may not be sufficient when the goal is to induce spawning.

Thanks again for all of the help.

Mark

RE: BTA reproduction

Ron Shimek — Sat, 03 May 2008 11:41:02 GMT

Hi,

The quick and undirty way is to look at the internal septa through the body wall. The so-called gonads (actually just aggregations of gametes) are located in the sides of the septa near the inner edges. If it is a healthy male that has had sufficient food and the right conditions to develop sperm, these areas will glisten bright white. If it is a female they will look dark green to gray.

RE: BTA reproduction

Mark — Sat, 03 May 2008 11:36:00 GMT

xroads, not a stupid question at all. The most practical way, as a hobbyist, to determine the sex of an anemone is to wait until it spawns and see what comes out. My females release eggs through their tentacles:

From the pictures I've seen, males release a white, milky substance through their pharynx.

Mark

RE: BTA reproduction

xroads — Sat, 03 May 2008 09:37:01 GMT

This may be a stupid question but how do you tell a male from a female. I am sure it is not as easy as lifting up their skirt & looking.

RE: BTA reproduction

Ron Shimek — Sat, 03 May 2008 07:30:18 GMT

Hi Mark,

You asked, "I'm not sure how the animals would sense tidal events? Would that just be a matter of the frequency and vigorousness of the waves they're subjected to?"

1) By and large these animals seldom subjected to waves. Most of the populations are too deep to have waves affect them unless there is a very serious storm. As a rule of thumb, waves cause no net water movement, only cyclic back and forth water movement on the bottom, and the depth to which that movement is felt is related to the height of the wave. The movement extinguishes at depth that is about 7 times the height of the wave. So, if the wave passing over the bottom is 3.3 feet (1 m) high, at a depth of 23 feet (7 m), there is really no net movement from the wave, and below about 10 feet the movement is really puny... In other words, wave makers for aquaria are another of those wonderful pieces of aquarium equipment designed to mimic some water flow that exists only in a marketer's imagination.

2)You really should read my AHABS issue devoted to anemones to learn about them. In any case, the animals surface is covered with sensory cells - these cells respond to tactile stimulation. What is water movement, but tactile stimulation?Additionally, tidal flux causes changes in all sorts of chemical concentrations - they might be responding to that as a secondary stimulus.

RE: BTA reproduction

Mark — Sat, 03 May 2008 06:52:19 GMT

Wow! Great information, thanks!

It sounds like having just the one male anemone and many females is a good arrangement then.

I'm not sure how the animals would sense tidal events? Would that just be a matter of the frequency and vigorousness of the waves they're subjected to?

As to the compound microscope, I've got a decent one here... now all I need is an observer who has a clue what to look for.

Thanks again.

Mark

RE: BTA reproduction

Ron Shimek — Fri, 02 May 2008 23:18:18 GMT

Hi Mark,

I think that it is more than likely related to the tides or some other physical attribute related to the moon than to moonlight. It has only been recently that a chemical system was found in some coral that could even respond to moonlight, and there is not experimental evidence linking gamete release to any sort of illumination changes. While there is a correlation with moon phase and natural spawning, I think that correlation has nothing to with the moon's light. The old saw... "Correlation doesn't imply causation,"is relevant here. If you think about this, variations in moon light are very "dubious" things to base a species' spawning on. If it gets cloudy for a few days/weeks with a storm pattern --- phfft. There goes this year... Spawning IS correlated to lunar periodicity. But, I don't think lunar light has any causative response. I think the lunar connection is with regard to tidal influences and these act to trigger animals whose spawning condition has been "set" by several months of associated changes in temperatures and day lengths.

Spawning synchrony is especially spectacular with regard to corals, because there are a lot of them doing their thing simultaneously and there are a lot of corals in a small area. However, it is not unique. Many temperate species spawn with the synchrony seen in corals, but their spawnings are cued by a combination of events - temperature changes, day length changes, and tidal events. In some temperate species I have worked with (sea cucumbers), whole populations can spawn in few minutes. Enough eggs are released in the water to change the color of bays from dark blue to green. These animals spawn on the first sunny afternoon after the sping equinox on an ebbing or outgoing tide.

The cues:

Day length (equinox),
Temperature (spring - three months of progressively warmer temperatures following six months of progressively dropping temperatures), and
lunar influences (outgoing tides).
Why it has to be sunny, I haven't a clue, but it does. Perhaps, that is a built-in safety check so that it isn't raining (lowering the salinity - as most echinoderms are sensitive to lowered salinity).

One other thing... Anemones, while related to corals, ain't corals. And their spawnings are not necessarily cued to the same things.

If this was my experiment, I would concentrate on getting the appropriate variations and synchrony in temperature and day length down pat. Then I would work on getting currents to mimic the appropriate tidal regimes. Then, after all of those mallards were in a linear array - and only then- would I even start to concern myself with lunar light. Personally, I think that part of the game is a waste of time. Frankly, for any anemone in water more than a few meters deep, I doubt that moonlight is intense enough to cause any sort of neural stimulation.

It takes several months or more of good feeding and appropriate conditions for the animal to grow the gametes. Typically the animals will spawn about 30% of their mass, sometimes more. They need a LOT of food for a LONG TIME prior to spawning. When my Stichodactyla haddoni female spawned, she would release 250,000,000 to 500,000,000 eggs per spawning event. These events occurred within a week or so after the spring equinox (day length influence from a nearby window). The female didn't start to have visible gametes in her septa until about 3 months before the equinox, but it is likely the gamete production started well before that time.

The animal has at least two things going on in it. First, there is the meiosis resulting in the production of the gametes. In the females, this stops at the end of first reduction division. That forms the haploid nucleus. After that, cells surrounding the oocyte pump nutrients into it. In effect, that grows the egg until it is "ripe." When spawning is triggered, second reduction division is completed and the egg follicle ruptures and the egg is released. In nature, the proximate - actual - cause of spawning in the female anemones (at least in the temperate species that have been studied) is usually the presence in the water of spawn from another spawning individual, typically a male. In any normal spawning invert population, with "ripe and ready" individuals, the first spawner is ALWAYS a male. That first spawn releases chemicals as well as sperm, as these move down current, one can watch other animals spawn - bang - bang - bang - as the male's spawn hits them. As they spawn, the chemical load of spawning critters can turn clear water a milky color - with my cukes it was a greenish "mist"... and every animal that is ripe in the population is triggered to go.

When spawning occurs, things will happen fast - and be over fast, and you will be one busy boy... Water change after water change will be needed. Once the males spawn, the problem is one of diluting the males' spawn to an acceptable level. Fertilization by more than one sperm does occur, particularly in aquaria, and it always kills the embryo. So... when these events start to appear imminent, you will have to watch the animals like the proverbial predatory avian dinosaur (a hawk). You will really need to control sperm abundance. You will have to have a good compound microscope available, etc....

Happy Trails...

RE: BTA reproduction

Mark — Fri, 02 May 2008 21:14:11 GMT

Thanks!

And, one more question: I've read a number of sources that indicate various coral spawnings occur X number of days after a full moon at particular times of the year. Do you have any idea if the moon's influence is a gravitational thing or if it's related to luminosity? Would you expect that it's necessary/beneficial to go to the trouble of trying to simulate the varying levels of nighttime light that correspond with the phases of the moon?

Mark

RE: BTA reproduction

magellan007 — Fri, 02 May 2008 10:52:32 GMT

My rbta split this last february. I try to keep my aquarium as "natural" as I can--with a wavemaker, proper lighting, and more importantly (and I may get criticized for it I let the temperature in my tank drop down at night to simulate realistic temps by several degrees. Also, I'm not sure if it matters with anemones, but my lunar lights have a program on them which simulates the phases of the moon.
I have pictures that I took of the whole process if you'd like to see it, though you are more interested in spawning, not splitting.

Good luck!

RE: BTA reproduction

Umm_fish — Fri, 02 May 2008 09:54:27 GMT

Good luck, Mark! Please keep us updated....

RE: BTA reproduction

Ron Shimek — Fri, 02 May 2008 08:23:08 GMT

Hi Mark,

You asked:"Do you have any recommendations as to what to vary, by how much, and for how long?"

For temperature: I would go to Google Earth, zoom in to a reef of your choice. Get the latitude and longitude. Then I would go to one of the NOAA/NASA sites that deals with Sea Surface Temperatures (SST), and find the records for the lat/long. Go back to the records for the mid-80s to eliminate the recent effects due to global warming. Get the average monthly temperatures and adjust your system accordingly changing the value each month for that month.

Then go to an online almanac or such, and get day lengths for the same latitude (longitude won't matter with that). And adjust the lighting for the same. Make sure they are synchronized.

The feed the animals the maximum they can/will eat.

Within a year, you should get spawing. One of my friends with a male has noted hers spawns in the spring. So - perhaps next year. This project should be at least a year long, maybe more.

There is information about raising larvae, etc, in several issues of AHABS. You might find them useful.

These animals are brooders, I think. I have seen images of larvae maintained within the females after spawning. This is not uncommon in anemones. So, when the males spawn, that triggers egg release and spawing by the female, but she will maintain the eggs inside her coelenteron. They will, in a short time, be visible as smudgy dark dots inside tentacles and such. Eventually she will release them to settle as crawl away babies.

"One other question: What influence, if any, does color have on the ability of E. quadricolor or S. haddoni anemones to reproduce? In other words, can a green BTA successfully sexually reproduce with a rose BTA?"

That is a good question. If those two color forms are different species, there may be little or no reproduction. If they are the same species you should get normal reproduction. In other words, color shouldn't make any difference. I don't think they are separate species, so the cross should be fine. The first generation may be all of one color - it would be interesting to know which - and then the second generation (crossing the offspring of the first when they mature) should show some interesting color variations.

Good luck!!!

BTA reproduction

Mark — Thu, 01 May 2008 23:14:39 GMT

Hi Ron,

I've finally located a spawning known-male RBTA that I'll be bringing in to hang out with my egg bearing female RBTAs. I assume the three major things I can vary, to encourage gamete developement and spawning are food, temperature and lighting. Do you have any recommendations as to what to vary, by how much, and for how long?

One other question: What influence, if any, does color have on the ability of E. quadricolor or S. haddoni anemones to reproduce? In other words, can a green BTA successfully sexually reproduce with a rose BTA?

Thanks!

Mark