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Medusa Worm, Good or Bad ?

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https://www.advancedaquarist.com/2002/11/inverts  

 

It's a type of legless sea cucumber and feeds on fine-particle detritus. Like many in the sea cucumber family, they produce chemicals (in varying concentration) for defensive purposes. As long as they are living happily and relatively normally, things are fine and they're a great member of your clean up crew. If one gets into a pump or something, it could very well release some of these chemicals which can suffocate other residents in the tank. Running carbon can help to mitigate this threat. 

 

Personally, I like certain types of sea cucumbers as a member of the clean up crew. I have two of the Holthuria species, one of which has been in my tank for over ten to twelve years now. Medusa worms are not Holthuria, but Apodacea. And that, apparently, makes the decision more complicated.

 

The article linked above talks to their needs, including fine particulate detritus, and the importance of properly identifying exactly which species you have or are considering saying,

 

"The primary problem with getting any of these animals, however, is that you cannot identify them by yourself, and will therefore have no idea of which species you are buying. That leaves you with no option but to trust your supplier about its care and requirements.".  

 

It concludes,

 

"All-in-all, however, despite how fascinating these animals are, unless you are confident of the identification of the animal, can provide suitable conditions for the animal to feed, and are willing to live with the potential drawbacks of keeping one of these animals in an aquarium, they are not really recommended for keeping in any aquarium. If you have a well-established reef tank, and you take adequate precautions to protect any pump intakes and/or overflow drains, and can locate one of the generalist detritivores that are suitable for the aquarium, I think that these animals make a fantastic addition to a reef tank, because they are both active and fascinating to watch."

 

It's also important to know what species it is because, apparently, some can grow to be 6-feet long! So I'll keep my tiger-tail and donkey dung cukes, but probably pass on the Apodacea.

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How toxic are anemones (standard BTAs & Rockflower types) in comparison? If one god forbid gets chopped up by a powerhead can you pick out all the major pieces and still be ok? What if one crawls under a rock and dies?

 

Thanks

Edited by realypk

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From what I understand, anemone aren't toxic the way the creatures being discussed here are. Anemones - if they should meet a powerhead - are hard on tanks from a nutrient standpoint. There's a lot of biomass that is now going to be decaying in the tank. Similar if a clam should die, one should take it out quick because it's a large mass of goop which can cause pretty serious nutrient spikes. The creatures discussed here (cucumbers, medusa worms, sea apples) as Tom said can be great for the tank. However, if they should die, they have toxins inside their bodies which can be released which can harm tank inhabitants (this is NOT the same kind of water fouling as a nutrient spike). Some stories of medusa worms even sound like one getting injured/cut, but surviving is enough to have the animal release its toxins and kill fish.

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2 hours ago, realypk said:

How toxic are anemones (standard BTAs & Rockflower types) in comparison? If one god forbid gets chopped up by a powerhead can you pick out all the major pieces and still be ok? What if one crawls under a rock and dies?

 

Thanks

Anemone's are a whole lot of water and a little bit of tissue. However, if one were to get chopped up, you might have some small pieces that you missed and there might be a release of a few stinging cells (nematocysts) in the water, but you're unlikely to get toxins. 

 

As for what would happen if one of these medusa worms died a "normal" death, I'm not sure. I'm guessing that any toxins aren't released but would be broken down slowly as part of the body decaying. The toxins are part of a defense mechanism and, unless triggered, probably stay in the tissues even after death. That is, of course, until the tissues decay. At that point, it's unclear if the toxins (which I assume are a protein) retain their character and are released, or if they start to break down alongside the rest of the cell mass and, by the time it's exposed to the open, it may be nothing but a bit of ammonia trickling out to be handled by the biological filter. 

 

I've had one sea cucumber die a somewhat normal death without any effect on the tank whatsoever. And a second, smaller one died when it got pulled up against a Vortech pump. Again, no effect on the tank. But both of these were Holthuria species (not a Sea Apple nor a Medusa Worm). While the record shows this to be probably the lowest threat of the three mentioned in the Advanced Aquarist article, it is expected to have the ability to produce and store toxin in its tissues. 

 

The things that bother me about the Medusa Worm (just from reading) is 1) You really need to be sure of exactly what species you have in order to understand the threat; and 2) some can get up to 6-feet long. The article seems to say that, unless you know what species you have, then you should pass on trying to keep it.

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Good news on nems, because I love them!!! So I'm considering getting a sea hare or lettuce nudi to eat algea and because i think that they look very cute... how toxic are these, I kinda really want one but like my clowns enough to not want to risk it if it could kill them.

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