# My oddballs - Terrestrial nemerteans and flatworms



## Umbra (Apr 21, 2017)

In light of the fantastic slug and leech threads, I figured I'd dedicate a post to some of my slimy, spineless wonders, the nemerteans (ribbon worms) and flatworms. I feel these are even more obscure in the pet trade than the others - the only flatworms most people know of are the species that are seen in science labs/freshwater shrimp aquariums. Ribbon worms most people have probably never seen outside of a few viral videos featuring marine species. I'd bet out of those who are familiar with them the majority aren't aware of the terrestrial species. 

I'll start with my freshwater ribbon worm, Prostoma cf. canadiensis. These were collected in a local river through the use of a bottom sampling dredge. They are pretty neat little predators of other worms, insect larvae and small crustaceans. The max size seems to be around 35mm. Their distribution is sporadic at best, being very common in some stretches and absent in others. Clear runs with mixture of cobble and sand sediment with an abundance of rooted plants seem to produce the best. They have been breeding for me on and off and seem to have a decently long lifespan. 











Next up is my terrestrial nemertean, Geonemertes pelaensis. These guys are much larger than the aforementioned species, with some of my specimens passing the 120mm mark. They are voracious predators of arthropods - mine have been eating primarily crickets although they'll take whatever else I'll throw in there for variety. The white isopods I put in there as clean up crew look to have been eaten as well. They are exceedingly shy and light sensitive, and only come out and forage in the dimmest of light or pitch blackness. As a result of this behavior I've only ever seen prey capture once. 
G. pelaensis are cyclic hermaphrodites, transitioning back and forth between male and female and some literature suggests that they may be capable of self fertilization during some points of their transitions. I've found a few egg sacs but I haven't seen any produce viable young yet. I keep a constant supply of springtails going in there just in case.
















I also have some unidescribed Caenoplana sp. These are not nemerteans but are terrestrial planarians. They appear to be generalist predators but seem to have a strong penchant for spiders in particular. This species reproduces by fragmentation - I've never seen them breed, never seen an egg case but I've seen them multiply by splitting. This has been confirmed by a professor in Australia who is an authority on terrestrial planaria. They don't appear to be as arboreal as G. pelaensis nor are they anywhere near as active even after lights out - they are more than content to simply sit in the same spot for days on end until it's time to feed. The largest one I have is about 85-90mm fully extended.






I also have a small species of terrestrial planarian, Rhynchodemus sylvaticus. These are tiny, maybe 30mm max but are efficient predators nonetheless. Mine have taken down prey as large as yellow sac spiders and small Trochosa sp. wolf spiders but I feed them primarily on Drosophila and springtails. They reproduce quite quickly and can populate a small vivarium very quickly. Most notable of this genus are the pair of conspicuous eyes on the head, they are IMO one of the neatest looking little worms. I don't have any good photos right now but I will try and get some good ones in the upcoming days. For now here is a photo of the vivarium I'm keeping them in!






I have a few more species that I will post about at a later date - if anyone has any experience keeping any ribbon worms/flatworms I'd love to hear about your experiences!

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## Umbra (Apr 22, 2017)

Here is a short video showing the movement and feeding of Prostoma canadiensis. You can even see the proboscis firing and injecting its cocktail of toxins!

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## LawnShrimp (Apr 22, 2017)

I've always wondered how to keep terrestrial planarians! When I was in Florida last week, I observed two species: _Bipalium kewense _ and dark brown one with clear eyes. I collected a few of them, but they disintegrated in their container, which was kept cool, humid, and with an earthworm to prey on. I found several more, but decided they were better off where they were. I'd love to try again with flatworms, though.


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## MTA (Apr 22, 2017)

Those are really cool, I have a Bipalium kewense but I haven't found anything it will eat.


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## Umbra (Apr 22, 2017)

Bipalium kewense is a more or less obligate predator of earthworms - related species may be slug or snail specialists so you could give those a try as well.

As for the dark brown with eyes, 2 species found in Florida immediately spring to mind - Dolichoplana striata and Platydemus manokwari. The former is long and thin, the latter short and thick and bears a yellow dorsal line running down the length of the animal. D. striata is another predator of earthworms while P. manokwari is a generalist with a preference for gastropods.


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## LawnShrimp (Apr 22, 2017)

Thanks for the ID. It was definitely a _Platydemus_ of some sort.


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## RTTB (Apr 23, 2017)

Very fascinating to me.

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## Umbra (Apr 23, 2017)

So it turns out I spoke too soon about G. pelaensis not giving me viable egg sacs...

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## Hisserdude (Apr 23, 2017)

Very neat little critters, I love terrestrial planarians, and the ribbon worms look cool too! 

I've kept a couple _Bipalium kewense_ before, (or at least a similar species), actually caught them here in Idaho, really surprised me to see them here, used to see them in FL all the time. Fed them earthworms, which they loved, got a couple large eggs from mine, they never hatched though.

Would really like to keep some again one day, I like the planarian species with the "hammerhead" look the most. 

Anyway, great thread, keep us posted on these unique little beasts!

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## klawfran3 (Apr 26, 2017)

I've kept a land planarian or two in the past, I never got them to feed. I heard they like earthworms?


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## plantecarnivore (Apr 26, 2017)

They are nice! I didn't know planarians were kept in terrarium!
I guess they are fast? Harmless to humans?


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## Umbra (Apr 27, 2017)

Land planarian diet varies from species to species, some are generalists that consume almost anything they can overpower (eg. _Platydemus manokwari, Caenoplana coerulea_), some are a bit more specialized and feed on arthropods/crustaceans (_Rhynchodemus sp., Artioposthia japonica, Dolichoplana mertoni_) and others are obligate feeders on a very specific prey item (_Bipalium sp_. will often only eat earthworms, slugs or snails depending on species, _Arthurdendyus triangulatus _feeds exclusively on earthworms). While research is always a good thing, these creatures are rather poorly studied with many undescribed species so there's a good chance that you might not be able to find any information about what a certain species eats. I'd advise searching the immediate surroundings and seeing what other creatures inhabit the area and collecting a few of each and doing feeding trials. They can go for long periods of time without feeding and can take a while to get settled into captivity. Most important is to try and keep humidity high and disturb them as little as possible - their natural microcosms tend to have little variance in temperature/humidity. I've found some species sensitive to air flow to the point that they won't feed for a good while after I open the enclosure. This is likely because air flow lowers humidity and I've noticed that many will try and retreat to a more moist and sheltered area. The best solution I've found is to have a small plug in the lid of the enclosure that you can remove and insert prey through there, thus causing minimal disturbance.

They are harmless overall as in they can't bite or physically damage you although because of the complex toxins in their mucus/their sensitivity I would advise against touching them unless necessary and obviously avoiding contact with eyes, mouth, open wounds, etc. after doing anything in the enclosure. At least one species (_Platydemus manokwari)_ is a paratenic host for the rat lungworm so exercise caution while handling this species.


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## Ratmosphere (Apr 27, 2017)

Super rad! Love the setup.


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## Umbra (Apr 28, 2017)

This morning I was greeted by a gathering of juveniles on the piece of driftwood, plus I found another egg sac!






I'll try to get photos of the egg sac once I clear my mirrorless camera's memory card, can't maneuver my phone to get a proper shot (I've been using my phone for every photograph I've posted, I apologize for any quality issues!). I did, however, manage to get a couple shots of one of the juveniles!











And finally, an updated FTS:

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## Umbra (Apr 30, 2017)

Not a great picture but here are 2 Rhynchodemus sylvaticus consuming a yellow sac spider

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## Umbra (May 10, 2017)

Got a couple shots of G. pelaensis consuming crickets, I will try to get some action shots soon!

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## Ghost56 (May 10, 2017)

Amazing enclosures and pics! What camera and lens are you using?

These sound pretty difficult to keep, but definitely are fascinating.


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## VolkswagenBug (May 10, 2017)

I'm not generally a big fan of worms, but these are really cool. Eventually, I want a pet bobbit worm, strangely enough.

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## Umbra (May 10, 2017)

Ghost56 said:


> Amazing enclosures and pics! What camera and lens are you using?
> 
> These sound pretty difficult to keep, but definitely are fascinating.


I'm using my smartphone (LG G5) and a cheap LED flashlight from Home Hardware. I also made a little macro filter out of a lens from a broken point and shoot digital camera for more magnified photos. I have a Sony NEX-5T and a macro lens but my girlfriend has been a bit slow with clearing our travel pictures and videos off the SD cards so no dice on that yet. Hopefully within a week or two I'll be able to use a proper camera!

@VolkswagenBug I have kept "bobbit" worms but not the infamous species - the actual bobbit worm (Eunice aphroditois) is nowhere to be seen in the pet trade. A variety of other eunicid worms come in with live rock and coral all the time and they vary in temperament depending on species. Some are very predaceous and will consume tankmates but they are not the well known bobbit worm that hides in the sand and has the trapdoor style jaws. These tend to bore into your live rock and come out at night, consuming anything they stumble upon.


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## VolkswagenBug (May 11, 2017)

Umbra said:


> I'm using my smartphone (LG G5) and a cheap LED flashlight from Home Hardware. I also made a little macro filter out of a lens from a broken point and shoot digital camera for more magnified photos. I have a Sony NEX-5T and a macro lens but my girlfriend has been a bit slow with clearing our travel pictures and videos off the SD cards so no dice on that yet. Hopefully within a week or two I'll be able to use a proper camera!
> 
> @VolkswagenBug I have kept "bobbit" worms but not the infamous species - the actual bobbit worm (Eunice aphroditois) is nowhere to be seen in the pet trade. A variety of other eunicid worms come in with live rock and coral all the time and they vary in temperament depending on species. Some are very predaceous and will consume tankmates but they are not the well known bobbit worm that hides in the sand and has the trapdoor style jaws. These tend to bore into your live rock and come out at night, consuming anything they stumble upon.


Yeah, I've seen videos and images of hitchiking _Eunice _in people's aquariums, so I hope to someday buy a few specimens from people who do get them and attempt to breed them for the hobby.


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## Umbra (May 12, 2017)

Just spotted 2 more egg sacs, they seem to like to lay them inside the driftwood so getting a picture of them is quite difficult. This is the best I could get without removing the entire lid which I don't like to do because of humidity fluctuations.

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## Tleilaxu (May 12, 2017)

Please make videos of your land "worms" hunting down and eating the spiders.

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## Umbra (May 13, 2017)

I only feed yellow sac spiders to the Rhynchodemus sylvaticus and only if I find them in the house during winter. Yellow sac spiders are introduced here and are considered by many (including other members of my household) to be a pest so I have no qualms using them as feeders, but I wouldn't take one from outside and use it as a feeder if I have regular feeders on hand. My R. sylvaticus generally get Drosophila and small crickets and I keep the tank stocked with springtails for the juveniles. I do have a few videos of the worms already on the prey but I'll try to get some of the capture as well.

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## Scythemantis (May 13, 2017)

I love these, as you probably know. I have the same large Florida species, which actually arrived as a hitch-hiker in one of my tanks, and have a population that comes and goes seasonally in my whip spider's tank. They never seem to attack her, so she's just too large for them, but they clean up her spare crickets and especially love isopods as prey.

I also recently found the largest one I've ever seen growing fat and happy in my back-up isopod colony!

I have however never seen juveniles like you're showing, despite my colony going for years!

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## Xafron (May 13, 2017)

So _you're _the one that posted photos of a worm eating a cricket.  I briefly saw it a few days ago and went back to try and find it later so I could learn more.  No luck.  

I'm strange.  I'd pick up a tarantula or scorpion before I touched something as mundane as an earthworm.  Something about worms really unsettles me on a level few other living things do.  That being said, this fascinates me.

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## Xafron (May 13, 2017)

When I was a kid I remember finding a flatworm under a rock in my front yard.  Just now googled it.  Based on what I remember, it would have been a "hammerhead" flatworm.  It was orange and/or yellow with at least one dark brown or black stripe down it's back, maybe a couple stripes.  Again, was long enough ago that the details are fuzzy.

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## Umbra (May 13, 2017)

@Scythemantis the species you have isn't the Geonemertes that I've been posting pics of, it's actually not a nemertean at all - you have the land planarian Caenoplana sp. Those reproduce via fragmentation which is why you never see juveniles! 

@Xafron maggots en masse have the same effect on me, a few and it's just fine but if I see a corpse of some sort full of them....yikes.
Your orange flatworm sounds like Bipalium adventitium, a pretty neat little predator of earthworms.

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## Umbra (May 13, 2017)

I managed to capture footage of Geonemertes pelaensis feeding! I apologize for the quality and the vertical orientation, G. pelaensis is negatively phototactic and I didn't want to scare it with direct light. Given the location of the worm in the tank at the time it was easier to capture with a vertical orientation than a horizontal. If I had a second set of hands I could have gotten a better video - hopefully next time I can get a better video.






You can see the proboscis fire out, which ensnares and then injects the cricket with a toxic cocktail via a small stylet. The proboscis is extremely sticky and the venom is fast acting, once captured prey is almost immediately subdued.

I will try to get video footage of Rhynchodemus sylvaticus next!

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## Tleilaxu (May 13, 2017)

So what's left when they eat? Amazing video. Hopefully you will be able to record the whole process of hunting to feeding close up.

Now excuse me while I watch it again.... And again....

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## Umbra (Jun 26, 2017)

It's been a while since I've updated this thread, but I have since let the Geonemertes viv grow wild. I have a ton of hatchlings and juveniles of different sizes and I want to disturb them as little as possible. I will be setting up a larger enclosure for another culture of these ribbon worms as the juveniles get a bit larger - they seem very delicate at small sizes.

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## arachnoherp (Sep 30, 2017)

Hey! Im not the only person that keeps predatory land ( and soon aquatic) planaria!

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## LawnShrimp (Oct 1, 2017)

It's like a jungle in there! Nice setup for the little squirmies!

What sort of care is needed for the South American Geoplanidae? I was thinking of obtaining a few of the vibrantly colored species. Do they need a fresh supply of earthworms and snails (I can easily breed leatherleaf slugs and_ Cepaea_) and are they illegal?

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## Salmonsaladsandwich (Oct 1, 2017)

Sometimes at night I see small, very thin black or brown worms up to around 1 inch with tapered heads sticking to the sides of buildings. They're probably flatworms of some sort but I suppose they could be nemerteans. Do they sound familiar? I might be able to take pics of them the next time I see them.

I also see _Bipalium adventitium _pretty often. A little while back I found a wild one out and about and put an earthworm in front of it, which it promptly wrapped itself around and devoured.

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## Umbra (Oct 6, 2017)

LawnShrimp said:


> It's like a jungle in there! Nice setup for the little squirmies!
> 
> What sort of care is needed for the South American Geoplanidae? I was thinking of obtaining a few of the vibrantly colored species. Do they need a fresh supply of earthworms and snails (I can easily breed leatherleaf slugs and_ Cepaea_) and are they illegal?


Depends on the species. Many Geoplanidae are consumers of gastropods or small arthropods (millipedes and isopods especially) so make sure you figure out what they consume. They can take a few days to weeks to get adjusted enough to accept prey so be patient and offer a wide variety of prey items until you figure out what they like to eat!



Salmonsaladsandwich said:


> Sometimes at night I see small, very thin black or brown worms up to around 1 inch with tapered heads sticking to the sides of buildings. They're probably flatworms of some sort but I suppose they could be nemerteans. Do they sound familiar? I might be able to take pics of them the next time I see them.
> 
> I also see _Bipalium adventitium _pretty often. A little while back I found a wild one out and about and put an earthworm in front of it, which it promptly wrapped itself around and devoured.


The small worms you're seeing with the pointy heads are almost definitely flatworms, to go any further with identification I'd need to know where you're located.

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## schmiggle (Oct 6, 2017)

Since when does MA have wild terrestrial flatworms!? I thought all the species were limited to tropics and subtropics.


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## LawnShrimp (Oct 7, 2017)

I find the species _Bipalium pennsylvanicum_ often around where I live, and recently found a bright orange one under a log. _B. penn._ can get as big as _kewense. _Flatworms are just more common, active, and colorful in the tropics.

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## Umbra (Mar 22, 2019)

I'm finally going to revive this thread as I do have some updates. I'm now attempting to culture them in 32 oz deli containers and so far so good - I have a couple egg sacs in one of them. I have several others set up with springtails and dwarf white isopods established in each one. I plan on introducing a few adults to each container and removing them once they lay eggs. At that point, hopefully the young will develop, hatch and have a ready supply of food for the first few weeks of their lives until they get large enough to take crickets. I have observed some scavenging behavior from the adults where one worm will kill a cricket and other worms will slowly congregate and feed.

I have also managed to capture a slightly better video of them feeding - I hope to get a really good video when I set up my next 2 vivariums, one of which I'll showcase in a build thread.

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## MoranDisciple (Mar 26, 2019)

Wow! Never even heard of owning these before but now I really want some. I live in PA so the only ones I have access to are the hammerhead obligate earthworm predators.


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## mantisfan101 (Mar 26, 2019)

Awesome specimens, if only I weren’t so afraid of them...


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## Umbra (Mar 27, 2019)

MoranDisciple said:


> Wow! Never even heard of owning these before but now I really want some. I live in PA so the only ones I have access to are the hammerhead obligate earthworm predators.


Bipalium sp. are interesting captives as well, give them a shot! I've kept one for a bit while I was in Japan, was awesome to watch it eat earthworms. Just make sure to change the substrate after each feeding - paper towel and moss substrate make this a lot easier as they produce a LOT of mucus.

You might also have Rhynchodemus sylvaticus, a small arthropod specialist that I posted earlier in the thread and Microplana terrestris, a generalist predator/scavenger of isopods, millipedes, snails, etc.

Go explore local forests after a period of rain, I find lots on the lower parts of tree trunks - they seem to like to hide under the bark of the conifers here.

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## MoranDisciple (Mar 27, 2019)

Thanks, I didn't know we had more than one species.


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## Umbra (Apr 29, 2019)

Just a couple quick photos, one of a baby worm and the parent and another of their new enclosure! The new enclosure is an orchidarium compete with a fogging sustem and ventilation fans, tons of springtails, isopods and (unfortunately) some fungus gnats established in there as well.

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## schmiggle (Apr 29, 2019)

Umbra said:


> Just a couple quick photos, one of a baby worm and the parent and another of their new enclosure! The new enclosure is an orchidarium compete with a fogging sustem and ventilation fans, tons of springtails, isopods and (unfortunately) some fungus gnats established in there as well.


That's beautiful! Very impressive. Would love to see it when it's in bloom


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