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Keeping Anemones

By Rob Toonen. Posted to Reefkeepers emailing list, Monday 16th to Wednesday 18th August 1999 and

Hello, I just bought a carpet anemone, Im not sure which kind but its kinda greenish and brownish and has a yellow mouth, my LFS said it would be ok in my tank 30 gal. My tank currently has two condylatis anemone, will my carpet be safe or????

You might have a lot more trouble than simply the fact that they are 2 different species. I recently wrote a "Letter to the Editor" about anemones after Phil Henderson's "Choosing your Next Anemone" article appeared in our local aquarium society newsletter. I'll post it here as well.

Although I applaud Phil's effort to provide more information about these awesome animals, I think he falls short on his goals. I think there is a critical piece of information absent from his article that all beginners (and even advanced hobbyists) should be told namely that the vast majority of anemones do not survive in captivity. Despite the fact that I, and many of my friends and colleagues were lured into starting marine aquaria by the fascinating relationship between the clownfish and their host anemones, I generally try to discourage most hobbyists from ever purchasing one for their reef aquarium. Part of the problem is that these anemones are not really "reef" animals in the typical sense of the phrase, and part is that husbandry of anemones is poorly understood. Despite the frequency with which I have overheard an employee in a petshop claim that "anemones are hardy animals that are easy to keep," I feel that many aquarists are mislead into thinking that anemones are appropriate for even a beginners reef tank. This couldn't be further from the truth, and I will try to explain some of the reasons why in this letter.

First, although the anemones that host clownfishes typically harbor photosynthetic algal symbionts (zooxanthellae, zoochlorellae, etc.), and algal production in intense light appears to be the major source of energy for anemones, all anemones require some animal prey for long-term survival. The shape and behavior of tropical host anemones both serve to increase the amount of area available for "harvesting" sunlight, and with few exceptions, intense lighting (typical of coral reef tanks) is required for anemones gain sufficient energy for survival. Some species are found exclusively in very shallow water and only in areas that are directly exposed tp sunlight (e.g., Stichodactyla gigantea), while others can sometimes be found in shaded areas, or even deep water environments (e.g., Entacmaea quadricolor). Depending on the habitat from which the animals were collected, very different levels of lighting may be required to maintain them successfully. Even in tanks with intense metal halide lighting in which stony corals are thriving, anemones are often reported to bleach and wither -- whether this is a result of too much light for a low-light adapted animal or a sign of other stressors is unknown. Furthermore, despite the fact that anemones look to be helpless predators just waiting for something to blunder into their waiting tentacles, most species appear to be prey specialists, and require both specific mechanical and chemical cues for the discharge of their cnidae (specialized stinging cells that anemones use to capture their prey). The cues required and the venom that is associated with these stinging cells both differ by species, and -- just to make things more complicated -- also differ depending on the condition and hunger of the animal tested. To date, there has been no cnidarian (the group to which anemones and corals belong) discovered which is capable of obtaining 100% of their nutritional requirements from light alone. All cnidarians (the group which includes hard and soft corals, anemones, gorgonians, mushrooms, jellyfish, hydroids and the like) require food to survive, and if the animal has specific feeding or prey requirements, it makes the job of maintaining them in an aquarium that much more difficult. Anemones seem to fall into that category, and there are foods that are readily accepted by one species that are basically ignored and dropped by others. To make this problem more difficult, different aquarists report that their anemones eat different foods this could mean that the animals have been misidentified and are not actually the same anemone species, or (more likely) that prey preference and feeding requirements differ depending on the animal in question and the conditions under which it is kept.

Secondly, and perhaps most discouraging is that these animals are essentially immortal in nature. They certainly appear capable of living several hundred years (yes, you read that right -- hundreds!), and do not seem to age in the way with which we are accustomed, but rather live on until disease, a predator or some natural disaster kills them. Despite their natural longevity, the life span of the vast majority of captive anemones is less than a two years. A recent survey of reefkeepers conducted by Joyce Wilkerson found that among a couple hundred respondents only 5% of hobbyists with *2-5 years* of reefkeeping experience had managed to keep their anemone alive for 2 years or more (this survey was specific to the clownfish/anemone host species Entacmaea, Heteractis, Stiochodactyla, Macrodactyla & Cryptodendrum). That's not very encouraging is it? To make it worse, among hobbyists with less than 2 years of experience, nearly half of the anemones purchased were dead within 3 months -- overall only 1 in 13 anemones survived for 3 years or more and only 1 in 32 anemones survived for 5 or more years in captivity (which by most accounts is considered success in this hobby). Even if we consider 5 years to be a ripe old age for these animals in an aquarium (this is roughly the equivalent of considering rearing a human to 1 year as being a "success"), only 3% of anemones purchased ever make it to this age (and if you read Shane's article entitled Dawn of the Dead, you should begin to realize that only a small percentage of "difficult animals" even survive long enough to make it home into an aquarium). This survey included many highly experienced and profession reef keepers. If I remember correctly, Alf Nielson topped this list of experienced aquarists with 32 years of reef tank experience, and the other respondents included many of the people who write the aquarium texts that we all refer to when faced with some difficulty in our own aquarium. Let me reiterate this despite the general expertise of the people who participated in the survey, only 5% of people can keep an anemone alive for more that 2 years! That is pretty abysmal for an animal with a natural life span of hundreds of years; *especially* given that, according to Daphne Fautin (co-author of the popular book Anemone Fishes and their Host Sea Anemones), removal of these anemones and their clownfishes is causing serious changes in the natural communities that she studies (and I heard rumors that she has recently become an active advocate of trying to outlaw the collection and importation of anemones). In their book, Fautin and Allen mention that some populations they once studied in the Philippines have become extinct as a result of collection and the habitat destruction associated with dynamite/cyanide fishing.

Third, many of the host anemone species (in particular several of the Heteractis, Macrodactyla and Stichodactyla species) are not generally found on the "reef" itself. Even with those species that do commonly occur living in close association with stony corals (e.g., H. magnifica, Stichodactyla mertensii and Entacmaea quadricolor), tank conditions that support excellent coral growth do not seem to support long-term survival of the anemones. Given that many reef-living anemones do not seem to flourish in reef tanks, it is not at all surprising that species living predominantly in soft sediments adjacent to reefs (e.g., Heteractis aurora, H. malu, H. crispa, Stichodactyla haddoni, S. gigantea, and Macrodactyla doreensis) do not seem to flourish in reef tanks. Aside from habitat differences, conditions of flow, lighting and food apparently required by anemones may differ from those required by corals, because anemones often bleach and wither in tanks within which corals are thriving and even reproducing. There have been a number of theories as to why the survival of anemones in captive aquaria is so low, including lighting, feeding, flow, typical nutrient loads and the list goes on, but the truth of the matter is that no one really knows. If anything constructive came out of the anemone survey, it is that every aquarist who had accomplished the feat of keeping an anemone for 3 years or more had a different explanation for their success. Lighting type and intensity, food type and feeding frequency, tank size, conditions and everything else questioned seemed to differ among the successful respondents, and there were no clear patterns that Joyce could pull from the responses she got to her survey. There do not seem to be any easy answers to specifically what people are "doing right" although there were many things that unsuccessful people are likely doing "wrong" with these animals (such as not feeding them or keeping soft-sediment species in a Berlin-style reef tank).

Fourth, the relationship between clownfish and their anemone hosts are not as simple as the average petshop would lead you to believe, either. Recent research has found that the ability of clownfishes to contact anemones results from an odd mixture of innate defenses (which vary by species), behavioral adaptation and developmental stage. Researchers from the University of Puget Sound examined the vulnerability of various developmental stages (eggs, 0-5 day old larvae, and 7-14 day old juveniles) of 10 species of anemonefishes (Amphiprion & Premnas) to being stung by 9 species of host anemones (in the genera listed above). Among other things, these researchers found that anemones failed to sting the eggs of any species of anemonefishes tested, but the larvae of all species were captured and killed by the anemones, regardless of species. If the researchers raised the larvae in a tank, and then allowed recently metamorphosed juvenile anemone fishes to contact a variety of anemones for the first time, they found that some species of clownfishes were protected from some species of anemone (but which larvae were stung by which anemones varied by species). Only A. percula (true percula clown) was immune to the stings of all potential host anemones as a juvenile, with most other species being stung by at least one species of anemone (most frequently Stichodactyla gigantea). Unlike Amphiprion, which was generally protected from several, if not most species of host anemone, Premnas biaculeatus (the Maroon or Spine-cheeked clown) was protected from only it's natural host species, Entacmaea quadricolor (the Bubble-tip anemone). As it turns out, all the species tested were capable of contacting the tentacles of the Bubble-tip anemone without being stung as soon as they metamorphosed into juveniles. Relatively few species were able to contact Stichodactyla gigantea (the carpet anemone) without being stung. Even in cases in which the juvenile clownfishes were stung when contacting anemones, most reacted by swimming violently and many were successful in breaking contact with the tentacle. That was not the case for the carpet anemones (Stichodactyla spp.) which generally captured and consumed any juvenile clownfishes which contacted their tentacles.

Those fishes that managed to escape initial contact could often acclimate to the anemone if given time, and become protected, but the results discussed above are for naive fishes and must therefore be an "innate" protection from the nematocysts of the host anemone species. In their book on clownfish and anemones, Fautin & Allen say "We believe that for fish that live with many types of hosts (such as Amphipron clarkii, which is the least host-specific), behaviour is likely to be more important to adaptation, whereas for host-specific fish (such a Premnas biaculeatus), biochemistry is probably the more significant factor." What they mean is that for generalist clownfish either accumulating anemone mucus through repeated contact and complexing compounds in the water in close proximity to the anemone or adapt their mucus to match that of the host anemone (the actual mechanism of behavioral adaptation is still unknown), while specialists ought to be protected by an innate genetic or chemical mechanism of some sort. This study shows that the generalist clownfish A. clarkii have an innate protection that appears similar to (and surprisingly effective) that of the extreme host specialist P. biaculeatus. The fact that both innate and behavioral protection is possible, and that the level of protection differs at different stages of the life of the fishes only adds to the existing confusion about exactly how and why the association between clownfishes and anemones has developed. At present all that can be said from the data is that there is no clear generalizations that can be made about the mechanism of protection from anemones -- the protection of anemonefishes varies by the species of host as well as the developmental stage of the fish, and in tanks the "rules" of host preferences and associations often seem to break down. It is not uncommon for a pair of clowns to spend all their time in a long-tentacled plate coral or some such "inappropriate host" despite an available anemone of the "correct" species nearby.

That brings me to my last point. The majority of clownfish sold in the pet trade today are captively raised and even wild caught ones do not NEED an anemone. Juvenile survivorship is significantly higher when associated with an anemone in nature (in order to survive heavy predation on newly settled fish), and the anemones do much better with the clowns to protect them from attacks of butterfly fishes, but at the size that clowns are sold for the pet trade (and especially in the absence of the typical suite of predators), clowns have absolutely no requirement for anemones in a tank. I believe that Phil Henderson is correct in his classification of species, because the animals he lists as the "easier to keep" species are the ones most commonly among the few percent that survive in aquaria (although in the anemone survey by Wilkerson it appeared that S. mertensii was the more easily kept carpet anemone, and Fautin & Allen report low success rates with the soft-sediment dwelling S. haddoni in aquaria -- this may be a simple misidentification or an example of the problem of different people using the same common names to refer to different animals). I also agree with much of the information that he reports on the care and problems with anemones (and you can get the book by Fautin & Allen for much more detailed information on all these species). The reason that I felt obliged to write this letter, however, is that Phil fails to mention anywhere in the article the extremely low rate of success with these animals in aquaria. Most of the people of whom I know who have long-term (again this means 5 years or so) success with anemones maintain them in a tank specifically designed to meet the needs of the animal, and in which the introduction of corals and other invertebrates is of secondary or little concern. If you intend to set up an aquarium with the specific goal of keeping anemones (with or without clownfishes), and gear the tank to that goal, I think that is great. I still encourage you to research the needs and natural habitats of the animals extensively, and to search out those rare pet shops that will be honest and informative (by which I mean somewhat discouraging) on the success rate of the average aquarist in keeping these animals. If you walk into a petshop and say "I want to add a Sebae anemone to my tank for my clownfish," and they show you to a tank of partially inflated white anemones and reply anything like "No problem, they are hardy and easy to keep," I would recommend that you find a shop that provides you with much better guidance.

Considering the confusing nature of the relationship between clownfishes and their anemone hosts, the apparent specificity and diversity of natural anemone diets and lighting requirements, and the fact that a pitiful 5% of even experienced reef keepers have managed to keep one of these anemones alive for more than 2 years (less than 1/100 of their potential lifespan), I hope that rather than reading this letter and considering what to look for when choosing your "Next anemone" that you will seriously consider whether your aquarium and ability are right for these animals. If you decide that you are up to the challenge, I hope that you consider what is the best way to go about "Choosing Your Last Anemone" rather than replacing yet another victim in your quest If properly cared for and allowed to live out its natural life span, these animals should become a family heirloom that should out-live not only you but likely your children and possibly your grandchildren. Until we reach the point where these amazing animals are routinely surviving for more than a couple of years in captivity, perhaps we, as responsible aquarists, should resist the temptation to buy them -- no matter how beautiful and fascinating they are.

I didnt read that article, so I dont know the list of anemones listed. In your reply, you mention some are easier, but most are a "stay away" for sure. In your knowledge, which are the ones that we should keep in our tanks when the tank isnt set up as a species tank? Is the e. quad a good candidate?

E. quad is *definitely* the best choice -- it is relatively hardy, one of the most common species of host anemone in the wild, they live on the reef itself and prefer hard substrate environments, and not only does well in tanks but have been reported to reproduce in many systems (e.g., Lawrence LeClair has some great pictures of the fission event in action -- "My anemone is a 2 generation tank raised specimen and is splitting. In fact, I documented it undergoing fission about a week ago . Go the anemone splitting pictures. I also have contacts with a guy in Pensicola whose E. quadricolor has produced 8 clones in 8 months." and we're all familiar with Michelle's success with these guys as well). E. quads are doing quite well in reef tanks, and are the only one that I'm recommending, and I still qualify that with "they're considered sort of difficult to keep."

It looks like we're dealing with info from 1996 by Joyce Wilkerson. That's 3 years ago. Is this still the current thinking? Again I'm not saying any one is right or wrong but has any one more current info?

Yes, that's the survey to which I refer in the post, and that is pretty much the current thinking. E. quad does well in tanks, variable to little success with any of the others. Do you think that has changed in the past 3 years? I still see the majority of petshops around here selling partially inflated white Sebae anemones that lack any nematocyst response when touched, and that turn to goo over a period of a month in the petshop unless some poor sucker buys them to watch them turn to goo at home... Are things different out your way, David? I'm not saying that there are no reports of success -- there certainly are, but the stats that Joyce compiled are pretty convincing when most of the reef "gurus" participated. If the guys who are writing all the books we buy to tell us how to keep the animals are failing with them, how good do you think the chances of the average aquarist is?

This was basically why I asked about the e. quad, as it seems due to the recent increase in feeding our tanks, there have been a lot of reports on e. quad spitting. However, I do not recall any other anemone reported reproducing on this list.

Ron Shimek's haddoni carpet releasing eggs once a year. Short of that, no, not that I recall.

Are you sure it was eggs Charlie? I'm not doubting you or Ron, I just want to clarify it because anemones generally have separate sexes. Having said that, it is actually difficult to say for sure because the gonads are often quite diffuse and gametic cells can be spread throughout the endoderm or in tiny packets surrounded by follicle cells and scattered throughout the mesoglea -- this makes it pretty easy to miss some. "Anomalous" hermaphrodites are often found in species in which sexes are "confirmed" to be separate, and simultaneous or sequential hermaphroditism appears to be the norm in a few species. In any case, individuals generally have a single sex, which they generally do not change (but I grant that may be as much our ignorance as the biology of the animals).

The developmental mode of most tropical anemones is completely unknown, but there are detailed descriptions of many temperate species. Among the species described, there is almost an even split between species that spawn pelagic larvae and those that brood internally. Becuase I had only ever heard of the release of sperm by spawning Entacmaea and Stichodactyla previously, I was starting to suspect that these species may be brooders, which makes it a lot easier to breed in aquaria. Of course, our sample size for spawnings is so low that I don't have much confidence in that guess, and if Ron's is releasing eggs rather than sperm, that guess is shot down ;-). Of those species that spawn pelagic or demersal larvae, there is again about an even spilt among those larvae that do and do not feed in the plankton. If we're lucky, the larvae will be non-feeding and have a very short time in the plankton, but if they release feeding pelagic larvae, or even if the larvae spend a reasonably long time in the plankton (some non-feeding species spend more than a year as a larvae before settling!) it may be difficult to impossible for us to raise the young in aquaria, even if we were to be successful in obtaining a spawning pair....

In talking to Ron back in February, we talked rather extensively about what would be required to actually breed these Ron's biggest problem, he said, would be finding a MALE anemone that he could fatten up and get into breeding condition. He did not seem to think that the spawning and ensuing fertilization/growout would be all that difficult. Merely engineering problems to solve were his words, if I remember properly.

From what I recall, Ron said its a she, and she has been release eggs for the past 3 years now, usually around March/April I think. Ron also mentioned that whenever this happens, its a massive water change time for him.

OK, so if he has a female, then the idea that they may brood is shot. Oh, well. It really depends on the species how much of a simple "engineering" problem the larval stage is. In some anemones, the larvae are non feeding, short-lived and easy to deal with. In others, they are non-feeding, spend a long time in the plankton and could be a lot harder to deal with, still others produce feeding larvae that (although certainly possible according to the Home Breeders FAQ someone wrote a while back ) would be much more of a challenge. I'm curious because I've been talking with the guy at FSU who posted the anemone fission pics and has been accumulating E. quads because his "males" have been spawning but not the "females" -- the two most obvious possibilities were that the females do not spawn (the anemones brood) or that he only has one sex (although as I explained in the original post, this is difficult to judge for sure, even if you kill the animal and dissect it).

Guess I'll have to suggest he get some more until one produces eggs and see what happens....

Created by liquid
Last modified 2006-11-24 22:38