# Some interesting info on "nemerteans"



## Umbra

I've been doing some research and looking through a lot of the photos and videos that people are posting of nemertean worms and it occured to me that the majority of the animals I'm seeing are not really nemerteans, but likely the flatworm _Rhyncodemus sylvaticus_. This species is widespread in the continental USA and has been found in Canada as well. It also predates on small insects so it more/less fills the same niche as the nemertean that shows up most often in the hobby, _Argonemertes dendyi_. 

How to distinguish between the 2:

_R. sylvaticus_ and _A. dendyi_ are both variable in colour ranging from a pale yellowish to a brownish grey. They also reach approximately the same size - ~2 inches tops when stretched, generally around an inch when resting. Their appearance and movements, however, are quite different. The animal that has the pointed end and the "finger waving" movement is in fact _R. sylvaticus_. These worms lack the trademark nemertean proboscis and instead hunt their arthropod prey by simply "pouncing" on them, capturing them with an expanded cephalic hood and then immobilizing them with mucous, draining the fluids out and leaving a perfectly dry exoskeleton. Here is a photograph and a video of _Rhynchodemus sylvaticus_:

_Rhynchodemus sylvaticus_














Several members have/had the nemertean _Argonemertes dendyi_ which has also been introduced to various tropical/subtropical areas including Hawaii and possibly Florida. These worms have a blunt rounded head and are generally more stocky looking than the flatworm. They move in a smooth gliding motion and hunt by firing the proboscis at the prey item and envenomating it. Feeding methods of the nemertean also leaves a dry exoskeleton. An easy way to identify _A. dendyi_ (or rather to confirm that your mystery worm is in fact a nemertean) is to lightly prod the posterior end of the worm and see if it fires its proboscis to try and escape as shown in the video below.

_Argonemertes dendyi_














While I'm not sure if this information is too relevant (I'm not sure if there are any significant differences that could aid in eradication of one or the other for those who want them gone), I figured at the very least it could potentially help others identify their little monsters.


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## frogparty

Very cool!! Thanks for sharing.


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## rigel10

Thanks for sharing. But how can we do to eliminate them from our vivs? I find them unaesthetic as well as lethal to the microfauna.


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## epiphytes etc.

They are both equally icky.


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## Viridovipera

Cool pictures. Do you know if it is possible to keep / breed Argonemertes dendyi?


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## epiphytes etc.

I'm sure it's not only possible, but easy. The question is, why would you want to?


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## Umbra

I don't have any dendros (yet) and I'm still learning about the plants and creating a relatively stable microfauna environment before jumping into the frogs themselves. I won't lie though, I do find both species of worms very interesting and I'm hoping I end up getting some of both species preferably now before I actually start with frogs. I'm setting up some tiny microfauna terrariums for each species and am actively searching for them at the moment. No froggers in my area seem to have any in their tanks unfortunately (for me anyways) so the hunt is still on! If none come in with any plants I buy I might have to hunt some of the _Rhyncodemus_ outside during the spring. I think that they're very interesting in their own right, just not ideal inhabitants of dendro vivs where they compete for them with food. 

The biggest problem I see with finding suitable controls for these species is the fact that anything that can deal with a 2 inch predatory worm can likely harm spawn/froglets as well. I feel that _Argonemertes dendyi_ could potentially be easier to control as they are protandrous hermaphrodites - they start off as males and upon reaching a certain size (I'll verify in some journal papers I've found later tonight) they become females. Therefore, I feel if you could find something that can eat them at a smaller size (asellus?) you could potentially wipe out the males and only have the larger females remaining, which would no longer be able to reproduce. I believe I also read that _R. sylvaticus_ prefers to burrow deeper in the substrate than does _A. dendyi_ so it may be more able to avoid predation at smaller sizes. 

I know that certain species of flatworm do predate exclusively on other worms/slugs/snails (think _Bipalium kewense_ but smaller size) but I'd have to do more research to see what species in particular predate on nothing more than other soft bodied organisms. Care has to be taken here as the species which can deal with these are probably more in the 2-3" range and certain species can and will overpower and consume isopods. One such example would be another species I've seen on here in some members' tanks, _Microplana terrestris_. These get a bit bigger, (2" resting) and are more generalist predators than the other 2 species I've mentioned which tend to specialize on arthropods. _M. terrestris_ prefers worms and slugs, so it'll likely eliminate the other 2 from a viv but has also been recorded eating our local _Oniscus asellus_ and several species of millipede, so I'm pretty sure that once the nemertean/flatworm populations are depleted, it'll likely start attacking dwarf isos as well. I think this species might be the cause of the conflicting reports of whether or not hobbyists' worms do indeed damage iso colonies. Here is a photo of _M. terrestris_ for reference:









If I can get a hold of some specimens of _R. sylvaticus, A. dendyi_ and _M. terrestris_ I'll get a few populations going and hopefully be able to experiment with different potential predators. I don't have frog spawn to experiment with (and I doubt I would even if I had, too valuable!) but I can at least experiment with woodlice of varying sizes so i can get an idea of prey consumption size or if they'll even eat the isos.

***EDIT*** I'm actually looking for specimens to obtain, keeping/breeding any of the above 3 species should be easy, they already do so in well set up vivs. Just recreate a similar environment on a smaller scale and feed with fruit flies and springtails, small spiders, etc. and I'm sure you'll find them do the rest of the work for you.


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## frogparty

So I did a little digging and there are several species of Rhyncodemus specifically evolved to live in phytotelmata! 
So strange that, as a planarian, they appear to look more like a roundworm 

I'd be extremely interested in breeding the "hammerhead worms" with the amazing coloration and leaf litter lifestyle. They look like some of the amazing reef flatworms I saw in Borneo


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## scoy

I have what looks to be sylvaticus. There yours if you pay shipping and supplies. Shoot me a pm if interested.


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## Umbra

scoy said:


> I have what looks to be sylvaticus. There yours if you pay shipping and supplies. Shoot me a pm if interested.


Thanks! I'm speaking with someone local who said he's seen them a few weeks ago but hasn't seen any since, if any pop up in his viv he said I can have them. If that falls through, I'll send you a PM!

As to those living within Phytotelmata, it wouldn't surprise me if a few of those are also making the rounds in vivs all around the world through the bromeliad trade. The specialization that exists at this level of life is truly amazing - I honestly think that these little worms are every bit as worthy of observation as the more traditional terrarium microfauna. Think about it, an animal as slow and ponderous as a worm is able to capture significantly more advanced lifeforms like flies and spiders. That in itself is amazing to me without even going into the unique adaptations they have to capture their much faster moving quarry.


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## scoy

Sounds good. Theres no waiting to pop up in mine tho, I have hundereds. The viv theyve taken over is a 10g terrestrial thats over grown with a glass top and no ventilation. So if you want to culture them I'd recommend a very wet/ humid enviorment.Also I'll be tossing everything within the month. I do not hold the same admiration for them as you.


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## Umbra

Hmm, I'm in Canada though so I'll have to shoot an e-mail to the ministry and ask them about import requirements (if any). They're native here so I don't think I need any import permit as any native earthworms don't require one and none of the predatory arthropods that aren't CITES require either. I'll get back to you soon!


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## frogface

I've found that the easiest way to collect nemerteans is to spend a lot of time and money on a new tank, getting it just right. Seed it well with microfauna and then add your favorite frogs.


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## DrNick

Umbra said:


> Care has to be taken here as the species which can deal with these are probably more in the 2-3" range and certain species can and will overpower and consume isopods. One such example would be another species I've seen on here in some members' tanks, _Microplana terrestris_. These get a bit bigger, (2" resting) and are more generalist predators than the other 2 species I've mentioned which tend to specialize on arthropods.


About 10 years ago I hauled a 32m (105') long _Lineus longissimus_ out of the Menai Strait. If I had that in my viv, THEN I'd be complaining  

Like you, I do like a good nemertean.... But quietly pleased that they haven't ever made it into my vivs, so far....

Nick


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## bradlyb

Umbra said:


> I honestly think that these little worms are every bit as worthy of observation as the more traditional terrarium microfauna.


When I first spotted these in my vivarium I was fascinated by them. However, they QUICKLY colonize a vivarium and become very unslighly. I would see hundreds of them come out about an hour before my lights would turn off. They crawl over the glass and leaves.

Just be careful to not cross contaminate any future vivs you plan to put frogs in. All of the plants from my infested viv won't be transferred to any other tank, I wouldn't even trust a bleach wash.


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## rigel10

Forgive me, but I do not have admiration you have for these pests! A little while ago I squashed two against the glass!
If I saw a 32m Lineus longissimus, I do not sleep at night nor I would go to the sea again!


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## Umbra

rigel10 said:


> Forgive me, but I do not have admiration you have for these pests! A little while ago I squashed two against the glass!
> If I saw a 32m Lineus longissimus, I do not sleep at night nor I would go to the sea again!


You monster!

I bought some Zoo Med Eco Earth and am currently keeping it at 100% humidity with some "forest moss". Many European hobbyists swear by them as vectors for nemertean/flatworm introduction so here's to hoping I get "lucky"!


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## Umbra

Just a small update: I got a few specimens of unidentified flatworms, either _M. terrestris_ or _R. sylvaticus_, possibly both. There is some variance in colour between the specimens so when I get the terrariums set up I'll put them in a petri dish and give them a good look over under a magnifying glass before they go into their respective terrariums. 

If anyone's interested I'll post up some pics/build journal of the terrariums I'm setting up for them. They're going to be pico sized but they will definitely be more than a bowl of dirt with some moss. I'm going to build a miniature viv complete with a false bottom and everything.


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## frogface

Yes please! I'm sure lots of us would love updates on this project


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## Umbra

Ok, I started a build thread over in the Members' Frogs and Vivariums subforum for anyone who's interested 

Here's the link: http://www.dendroboard.com/forum/members-frogs-vivariums/155362-microfauna-micro-vivarium-1-a.html


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## Umbra

Just found some more information on _Microplana terrestris_: they can reproduce asexually  If _Rhynchodemus sp._ can do the same then all it takes it a single specimen to start a culture of clones. As far as I know, the much rarer nemerteans don't reproduce asexually but are protandrous hermaphrodites.


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## papa_mcknight

This thread is just what I needed. I recently have found two mystery slithers in my viv which I immediately removed with tweezers. They were around 1cm in length and broke apart when picked up. I did not see a Proboscis while this was happening and didn't seem to be very rounded so im guessing they will be R. sylvaticus. It's only now that I notice a lot of the larger springtails that used to hang around in my coconut feeding dish have disappeared, leaving only the smaller generations. Hopefully there isn't a large population in here. My viv is frog free and im planning on a little replant soon so while doing so I will have a good rummage and see if I can remove and identify the culprits. 

I will be following this thread with interest 

P.s. I have found both of mine on the damper side of my driftwood, just incase anyone has difficulty finding any in leaf litter and soil.


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## Umbra

I'm glad this thread was able to help you!

I know some people have spoken of using other species of flatworms to control these but I'd advise against doing it unless you're 100% certain of the species you're putting in and even more certain of the diet. Many flatworms are opportunistic predators that aren't too particular about what they consume - if they can catch it it's fair game. Someone on another forum posted a couple pictures of _Caenoplana coerulea_, a smallish (3-5" average) colourful blue and yellow species consuming a young gecko it managed to capture. This species has been introduced to the states and has spread across the southern reaches of the continent from California to Florida, Texas, Georgia, NC and even Iowa. I'm sure something around that size wouldn't have any qualms munching on a thumbnail frog. 

I'm sure everyone has noticed that their flatworms leave small mucus trails on the glass they've crept over. Apparently at least some species of flatworms secrete mucus that is extremely foul tasting which explains the relative lack of suitable predators. Some have theorized that they might have certain secretions that may be toxic in nature as it's been noted that prey is often subdued extremely quickly after contact with the mucus. Also, some aquarium enthusiasts have observed their aquatic shrimp being almost paralyzed after having an aquatic planarian attack them for an instant. From all the literature I've read, flatworms are their own worst enemy as many species are cannibalistic or at the very least will consume other species of flatworm. If the smaller _Bipalium_ species will eat other flatworms then they are probably our best bet at controlling the common flatworms in our vivs as I haven't heard of _Bipalium sp._ consuming anything other than worms, slugs or gastropods. Of course, more research should be done in the form of food experiments before any conclusions are reached.


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## rigel10

I know that nemertean also can reproduce themselves by cutting them in two parts. They are pests! It would be interesting to find a method frog safe to delete them - apart from your interest, which is laudable in my opinion.


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## Umbra

Small update:

It's been a while and I've started culturing the _Rhynchodemidae_ flatworms. I've tried several different species of isopod and in a small container (think FF culture size) most of the medium to larger isopods seem to eat their eggs - I'll have adults but never see any babies. I removed the isopods and worms of different sizes started to appear. I reintroduced the isos and the population of nemerteans stopped growing but the small and large specimens still remained. From what I've observed the isos will eat the eggs but won't touch the live worms. I believe this has to do with the mucous that they secrete. They kill by subduing their prey with a mixture of mucous and digestive enzymes. Finding predators that can and will actually eat them but can't harm frogs is actually proving to be quite difficult. They can kill and consume disproportionately large creatures - here is a picture of a yellow sac spider (_Cheiracanthium sp._) that I caught in my house and threw in as a test and it's killer(s) beside it. The spider was healthy and active when I threw it in the container it built a web near the top, returned 3 hours later and found it like that with the worms on it. They crawled off once I placed a light on the carcass to take a picture.


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## rigel10

Also I have noticed that nemerteans have almost disappeared in my two vivs contaminated after I introduced isos, especially the brown woodlice. But it took a little time, four or five months at least.
Even the drastic reduction of springtails, eaten by nemerteans and frogs, has contributed in reducing them, in my opinion.
Now I put the springtails in front of the frogs, so they can eat them easily.
Further on, I will try to restore in these vivs the microfauna.
I am comforted by the idea that I am no longer forced to redo the vivs contaminated. I still wonder how the nemerteans can be finished in them after I sanitized with bleach and water the plants.
Umbra, thanks for your experiments and if you find a more effective method to eliminate these pests, please, share it with us.


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## Umbra

For smaller enclosures isopods *might* be a possible vector to keep them relatively under control as well as controlled feedings like you mentioned. However, in larger enclosures with an abundance of both vertical and horizontal space I feel that you'd require an unreasonable amount of isopods to realistically cover enough ground to find all of the potential crevices that the worms can deposit eggs. That also doesn't take into account all the vertical space the worms can use as well. Furthermore, I'm not sure how eager they are to eat the eggs as I didn't really provide them with much of anything else. These are things I'll need to test in the future once my present population increases in size or if I can get a hold of more worms.


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## papa_mcknight

My nemertean number decreased with lack of springtails, but also what looked like a slight common centipede and slug problem may have helped. A British frogger here has had success with placing a slice of apple in his viv overnight and pulled it out covered in nemerteans like you do when removing unwanted snails from vivariums and aquariums. I bought some Gala Apples but they didn't seem to go for that flavour.


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## rigel10

I was very skeptical about isos (the usefulness of which I read long ago). I've tried and I've noticed a reduction of them (from 10-20 per day on the front glass of the vivs to 1-2 or less every 5-6 days). 
But the population of springtails has almost disappeared. 
Less food = less nemerteans. And isos help! 
However, I follow and I will follow your experiments with interest.


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## edaxflamma

I am hesitant to resurrect an old thread but there is so much good information here I felt think it should all be in one place. 

I'm not sure if the OP is still doing their experiments but as I was flipping through some old books of mine I had an idea. 

If it is true and at least one of the "nemerteans" in everyone's vivarium is actually a terrestrial planarian (Rhynchodemus sylvaticus), given that planaria are one of the most heavily studied organisms I wondered if that might be of any use to us.

The reason I bring this up is...

Thinking back to high school bio, we subjected California blackworms to various molar concentrations of caffeine and nicotine, tried to find the LD50, observed vascular changes, etc. etc. 

Surely the same principles could apply here? Could one of these (I hesitate to say) relatively innocuous chemicals be used as a possible treatment? 

The big questions I have still yet to search, and perhaps someone knows and can chime in, are:
1. Does caffeine/nicotine regularly degrade under various vivarium conditions?
2. If so how long would that take and would it be worth while in the grand scheme of things.
3. Could the combination of time and misting/spraying with distilled water help dilute it down to acceptable levels.
4. If these chemicals do not degrade, would you be able to dilute them or wash them away with X amount of misting/spraying washes.

Knowing that amphibians are generally very sensitive to this kind of thing made me very hesitant to bring it up in the first place but I figured those with more knowledge on the subject could chime in.

Is this too far-fetched of an idea?
Remove frogs, mist the viv to draw out the little buggers, brew some extra strong black tea, hose them down, wait, repeat to draw out next generation, wait, repeat, (optional dry ice bomb immediately post tea spray hoping that they have increased O2 demands), observe for stragglers, if all clear begin "detox rise", mist as often as botanically possible and/or wait for chemical breakdown, add in 30% extra wait/detox time to be safe and keep on frogging?

Thoughts?


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## Umbra

So I've been doing some more research and it would appear that finding a creature that will reliably eat these flatworms might be a problem. A study was recently done on 2 species of hammerhead flatworm (_Bipalium kewense_ and _Bipalium adventitium_) which found that they produce tetrodotoxin in their mucus, likely as a defensive as well as predatory mechanism. Apparently the egg cases are even more toxic than the worms themselves: PLOS ONE: Confirmation and Distribution of Tetrodotoxin for the First Time in Terrestrial Invertebrates: Two Terrestrial Flatworm Species (Bipalium adventitium and Bipalium kewense)

The little buggers that show up in vivs are actually capable of taking down insects far larger than springtails and fruit flies - here is a video of one of mine attacking a largish (~8mm body) yellow sac spider. I apologize for the quality, it was a quick vid snapped on my phone.

https://www.youtube.com/watch?v=IavswJ0l6zs

You'll notice that when the worm tags the spider the first time the spider struggles quite a bit then seems to suddenly stop, then the second attack results in only a slight struggle and complete paralysis of the spider. It appears that these flatworms also use some form of toxin, if not tetrodotoxin then probably a similar neurotoxin that is obviously quite potent. That would go a long way in explaining why most creatures that would happily munch on earthworms seem to ignore flatworms almost entirely. 

I've so far had limited success with the larger isopods and a few random snail species but those were in small, controlled environments. In a large vivarium that has multiple food sources, I'm not sure how well they would work. In large numbers both of those can become pests themselves and, in larger containers, I find that once the egg predators are removed the worms seem to start appearing more frequently again. In larger containers they seem to persist unless I let the terrarium dry out or stop feeding them entirely, neither of which are practical solutions for enclosures with frogs and humidity loving plants.


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## edaxflamma

Seeing as you have the set up, would you be interested in some nematophagous fungi to test their effectiveness? I could likely send cultures your way if you were interested.


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## Umbra

I feel the chance of success would be quite low. Nematodes are significantly smaller than even newly hatched flatworms and far more delicate. Even tiny flatworms can anchor themselves and hold struggling flies, I doubt the trapping variety of fungus would have any effect. These fungi also seem to rely on detecting ascarosides which are molecules unique to nematodes so it's quite likely that they wouldn't even recognize flatworms as food - flatworms aren't even closely related to nematodes. I would imagine that the endoparasitic species would have similar problems in recognizing planaria as hosts - I feel it'd be just as likely to infect an earthworm as a planarian given that they seem to rely on chemical markers for prey detection and spore germination.

Furthermore, I'm located in Canada so I have no idea how importing specific species of fungi cross border would work, especially one that has potential as a biological pest control agent.


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## edaxflamma

Yeah I can understand that. I was thinking more along the lines of the endoparasitic varieties relying on spore ingestion etc. but you are probably correct. I know we have to jump through some hoops at work shipping fungal material to Canada so I think that's the end all there. Keep up the good work though!


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## JPccusa

Why not revive this thread with this short video?


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## topher

JPccusa said:


> Why not revive this thread with this short video?


Saw this on Facebook yesterday... Completely nuts !


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## epiphytes etc.

Of course, right when I'm eating rice noodles D:


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## rvsur

JPccusa said:


> Why not revive this thread with this short video?


Can someone tell me what just happened so I can be slightly less weirded out.


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## K3viin128

Old thread; but none the less gave me a large amount of information to the worms that are inside my viv.... Sometime a little digging in old threads helps out big time...


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## Dartfish

Here is an image of my hammerhead flatworm bipalium kewense, ive had it for a few months and this individual was grown from a tail piece of a larger one i found


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## Deltagraphic

Hmm, I have had what I thought to be nemerteans in my various insect and snail vivs for at least a year and, unsurprisingly considering I keep bugs/snails, I was pleasantly surprised when I found them. Mine look mostly similar in body-plan to the ever present soil nematodes but are larger, brown and have an active hunting/striking posture that I haven't ever seen in a nematode. All of my vivs have been seeded both with soil/wood from old-growth redwood stands and soil from previous vivs so the microfauna should be about the same across all of my tanks. I am preparing to introduce mantellas into my 18x18x24 exo terra and am wondering if these nemerteans will eventually overpopulate. So far, I've never seen more that one at a time and my soil-arthropod biomass remains massive. Could it be that these are either not nemerteans, are a less invasive species, or are being kept in check by one of my other arthropods? Alternatively, is the explosive population and decimation of micro-fauna an exponential function that doesn't become apparent until a year or more down the line? If this is the case I might opt to put the mantellas on hold and build a new viv for them that I will seed species by species after some deli cup quarantine.


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