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FAQs about Flatworm Identification 2

Related Articles: Flatworms (incl. Planaria), Pest Flatworm Control by Anthony Calfo, Worms, Featherduster Worms

Related FAQs: Flatworm Identification, Flatworm ID 3, Flatworms/Planaria 1, Flatworms 2, Flatworms 3, & FAQs on: Flatworm Behavior, Flatworm Compatibility, Flatworm Control, Predator Control, Chemical Control, Flatworm Selection, Flatworm Systems, Flatworm Feeding, Flatworm Disease, Flatworm Reproduction, & Worms, FAQs: Worm Diversity FAQs, FAQs 2, FAQs 3, & Worm IDs 1, Worm IDs 2, Worm IDs 3, Worm IDs 4, Worm IDs 5, Worm IDs 6, Worm IDs 7, Worm IDs 8, & Worm ID FAQs by Group/Phylum: Flatworm Identification ID, Nemertean, Proboscis, Ribbon Worm ID, Nematode, Roundworm ID, Nematomorpha, Horsehair Worm ID, Acanthocephalans, Thorny-headed Worm ID, Polychaete Identification, Polychaete ID 2, Tubeworm ID, Hirudineans, Leech ID, Echiuran Worm ID, Invertebrate Identification

Strange Creature   7/2/06 OK, so I've been meaning to ask you guys (and gals) about this creature, but I've only caught glimpses of it until now. Its about 3-4" in diameter and roughly circular. It has no discernible body and when it moves (which it can do pretty quickly), it flows almost like water, following the contour of the rocks. It is grayish-brown, spotted, and very thin. If touched it gets agitated and the edges become very scalloped. I'm sure someone there must know what this thing is. It's certainly interesting. Its right below the orange sponge in the 2nd picture and roughly in the center (towards 8 o'clock from center in the first. Thanks TJ <Good description and nice photo of a resident flatworm. See similar here: http://www.wetwebmedia.com/flatworms.htm Mmm, though many folks seem to panic re such animals presence, I would leave this one be... not likely harmful. Bob Fenner>

Black Nudibranch appears at night Hi WWM guys- <Malcolm> Another ID question.  Attached is a blurry photo of a pure black Nudibranch (I guess) that appeared first about six months after the live rock was placed in my 125 gal.  We've seen it twice since the first time - only at night.  It moves very slowly on the rock.  Appears to have two tiny antennae.  It is pure velvety black.  About 2 square inches and flat as a piece of paper.  I've searched my books and the net and can't find it. <Looks like a flatworm to me, Pseudoceros sapphrinus. And not a problem. Please see here: http://wetwebmedia.com/flatworms.htm> (Up 9 months, 30g Eco-style sump with Caulerpa, 150#LR, 2"sandbed,2 soft corals, 2 polyp colonies, scattered native corals and polyps, peppermint shrimp, pistol shrimp, 20 snails and 5 hermits, 7 Chromis, tang, 6-line wrasse, goby, Dottyback, pair of perculas with a bubble-tip (now cloned into two), too much red hair algae; 1.024, 80F, 0 ammonia, 0 nitrites, 4 nitrates, 6x65watt compact fluorescents) You guys are invaluable to beginners like me! Malcolm Young, Brevard, NC
<Glad to share. Bob Fenner>

Mexican Skirt Dancer (Pseudoceros mexicanus), not Spanish Dancer (Hexabranchus sanguineus) or Mexican Dancer (Elysia diomedea)?   3/7/07 Hey <Yo!> I'm pretty sure I know the Scientific name to this but I'm looking for pictures of it but can't seem to find any. Its common name is swimming flatworm (Mexican skirt dancer). <I have not found any images of (Pseudoceros mexicanus).  I'm presuming you don't mean a Spanish Dancer (Hexabranchus sanguineus), which isn't a flatworm, but a Nudibranch, or a Mexican Dancer (Elysia diomedea) which is a sea slug.  But we do have pics of these two! > I think the Genus and species are Genus: Pseudoceros  Species: Mexicanus. However, I'm not fully sure. If you could confirm this that would be great. <There is a flatworm with this name, Pseudoceros mexicanus Hyman, 1953.> Also this If you could send me a pic of it that would be awesome I've searched all over. <Nothing that I've found on WWM. RMF any in your personal collection? <<Mmmm, no unfortunately. RMF>> All right; thank you for your time <You're welcome, sorry I couldn't be more helpful.> -A person who loves marine biology <Ditto!  -Mich>

ID this worm(?) please, and Medusoid     1/17/06 Dear Sir/Madam, <Will you read my book? Oh, sorry, not one of the Beatles here> I have my marine tank 29 gallon BioCube in the 5'th week of cycling. I also have about 28 lb of live rock and about 2 lb of live sand. This past weekend I've added an 11 snails and 6 red-legged hermits. Snails took a very good care of the algae on the rock... Everything seems to be looking perfect, until I found some kind of worm(?) on the inside glass eating the pods. <Mmm, yes... some sort of Platyhelminth...> I have an extremely high pods population: when I clean the glass inside, they will reappear within the same amounts in about 2-3 days. I'm attaching a picture with 2 critters one on the top is an unidentified one (length of about 3-4 cm) and the bottom the pod that is about to be eaten. This thing on the top moves really fast! I also noticed, that there are one that is splitting on the glass, that looks like there will be another two instead of one soon. It took that thing to split up about 5-6h. Thank you very much for your time and effort in maintaining such an excellent site. <Welcome... these are flatworms... I would just wait, let them pass on their own here (likely will in short order... no need to try and selectively poison...)> There are also something else that I noticed today...I turned off my powerhead, and noticed those little tiny thing (about 2-3cm), that move by pulsating. Looks like jellyfish. Are these ones good or bad ? <Mmm, could be bad... but likely will also go of their own accord... Are likely some sort of tissue-grade life (Cnidarian, Ctenophoran)... that are arising from a hard substrate...> Unfortunately I were not able to make a good picture of it, but it is on the 2'nd picture... <I see this... a Medusoid of some sort... you can read about such with a search of WWM, the Net... and the terms above.> Thank you very much for all your help...Regards, Andy Stavickis
<Welcome. Bob Fenner>

Flatworm? Hi WWM crew, <Hi Manus> My reef tank has been running for more than a year and everything seems fine until recently I notice something like flatworm are rapidly populating.  But I'm not sure what it is actually.  I've attached a photo and hope you can help me to identify.  BTW, should I worry about this. Regards, Manus <Is a flatworm of some sort. Please read through the postings on www.WetWebMedia.com re these animals. Can likely be ignored at this point. Bob Fenner>

Copepod eating flatworms... harmless 8/28/04 Hi guys, Just a quick question.  my tank has been set up for a little over a year now and has had its ups and downs.  I was watching the tank when this odd creature passed my line of sight.  I watched until it settled on a piece of LR and marked the spot with my flashlight.  I got a syringe I use for testing the water and was able to suck it up.  The pic attached here is of that syringe so you have a little bit of a size reference.  I have no idea what this is or where I could start to look for information on it.  Any help is greatly appreciated.  Another size reference would be that it is about the size of a lower cased "I" at 10 font.  Thanks again, Todd <this creature is a harmless copepod eating flatworm. They wax and wane as copepod populations do. Most every aquarium has these critters. No worries :) Anthony>

ID Flatworms 2/10/05 Thanks a lot for your time and for supplying an invaluable source for us reefers. <Always welcome> Now the groveling is out of the way I wonder if I could pick that wonderful marine brain of yours? My 50g reef has been set up 6wks and I have just started to add a few inverts, over the last week I have added 6 blue legged hermits, 1 red legged and 6 turbo snails, all seem very happy and active and are eating well, but as soon as I introduced the blues, while waiting for the first inhabitants of my reef to disperse. I noticed one of the blue legged isn't blue! <Arghhh... some rogue species do enter this way. Do be very careful> It is completely chalk white! After much searching over the net and through books- to no avail.  <do look in Paul Humann's "Reef Creatures"> I came to the conclusion that this must be an albino!  <Ahhh... well, hmmm. Just because you could not find a book that ID'ed the creature? Your pulling my leg, right? :)> But I have observed further and the white hermit has slightly different features, the right claw is about twice the size of the left one, and as the other crabs stroll around the white one sits in the sand with his shell buried at the front of the tank! he rarely walks far! he has shed once so I am assuming he is good and healthy- any ideas? <Many Diodenidae species> And is he reef safe? <Hard to say, but the large claw is a concern. Form Follows Function. That claw has a use/need> I do hope he will be ok, as I have gotten rather attached to the little guy! Also I have a few small, what appear to be sea slugs in the tank, they are about half the length of your little finger nail.. <Please do read, learn, and apply quarantine habits my friend. These risks and dangers will be eliminated> ...and just have that Nudibranch shape with the rounded head, and a kind of a lyre tail rear!  <Chelidonura?> But after a bit of reading thought they might be flatworms! <Hmmm... similar general description, and preying on copepods if so, perhaps. A Small white variety that fits that descriptions is rather common in tanks> but cannot find reference to any flatworms (or anything similar) this colour- they are a kind of translucent white, sort of opaque- any ideas their? <Ah, yes... copepod eaters> And if they are a pest, any methods of removal or reef safe predators I can introduce? <They are harmless> Thanks a lot for your time, and the service you provide.  Mark <Best of luck and life, Anthony> 

Flatworm ID - 04/19/2006 Hello and greetings from sunny Woodland Hills CA, <Hello.>    Please accept my apologies for not sending this directly through your website link - somehow I managed to type-in the outgoing server information wrong and now I can't seem to correct the format in my computer. <We've gotten it just fine.>    I want to thank you for your website; it is an excellent resource for novices like myself trying to create the most natural environment possible for my marine pets. <Thank you, we're happy to help.>    By way of background, I have been keeping a 40 gallon hex tank the "old school" way (undergravel filter and dead coral skeletons) for years with some success. I recently woke up to the new techniques available and upgraded my tank to live rock (plus protein skimming, vigorous water movement and addition of a 96 W power compact light and UV sterilizer). Unfortunately, I had some trouble along the way keeping water temperature stable and had to remove all my fish to quarantine for Ich treatment. <Ouch!> Right now, I am in week 4 of a (minimum 12 week) fallow period. The tank still contains a small Diadema urchin, two cleaner shrimp, one Peppermint shrimp and a small colony of Zoanthids (live rock stowaways) which are all doing very well. Ultimately, I would like to add back a few fish in this tank, plus a small green star polyp colony currently in quarantine (also a live rock stowaway) and maybe some mushroom polyps later. <Ok.>    Due to the stress of having to remove everything to catch and quarantine my fish, the tank had to recycle through its algae cycle. It is through the diatom period and nearing the end of the Cyanobacteria phase. The tank now is going through a hair algae bloom, which is subsiding. Water chemistry is excellent. Now for my question - over the past week or so I have been noticing ever increasing levels of what appear to be small slugs or snails grazing on algae. They are about 5-10 mm long and a translucent white-blue color. They seem to be soft bodied with an internal "shell". Photos are attached. Would you kindly advise if you can help identify and provide any pertinent information. <This is a flatworm. Perhaps Amphiscolops sp.> If this is a reason for concern or fish food later? <Harmless. Here's some more info. http://www.wetwebmedia.com/flatworms.htm > They are definitely multiplying pretty fast. <Can reproduce by splitting. They can't really exist in high flow areas though, are they growing quickly in dead flow areas? Likely won't last too long.>    Thanks in advance for your reply. <Hope it helps some.>    Scott (AKA SharkBait)

What the H, E, Double Hockey Sticks is This?   1/8/07 Hi! I was wondering what this is. it is slightly green in color, very flat, no shell, <That you can make out> around 2 inches long and almost as wide. Movement is similar to a snail, almost looks like some sort of Nudibranch. Cannot see eyes, mouth, etc. It's kinda trippy, little freaky!  I have been having problems with margarita and Astrea snails dying, don't know why. I found this creature simply draped over 2 margarita snails in the sand at night, trying to get at them. I think it was feeding on them but not sure. Do you guys know what it is? <Mmm, is it very flat, wavy at the edges? If so, might be a flatworm of some sort... If not, possibly a sea slug of many possibilities...> It is certainly out of my tank! It took some effort to capture, but I was successful. It is currently in a cup with pinhole size holes in it, in a net, in the sump! LOL! I had it in a sealed cup with bigger holes (approx.1/4 inch in diameter). Damn thing escaped within 3 minutes! captured it again. I am gonna bring it to my LFS for identification tomorrow, but not sure if they can help. Attached to this e-mail is the best photo of it. Thank you! <Oh! Does appear to be a Platyhelminth to me. Bob Fenner>

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