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FAQs on the Hydrozoan Identification 6

Related Articles: Hydrozoans, Cnidarians, Fire Corals, Stylasterines, Hydrozoan Jellies,

Related FAQs: Hydrozoan ID 1, Hydrozoan ID 2, Hydrozoan ID 3, Hydrozoan ID 4, Hydrozoan ID 5, Hydrozoan ID 7, Hydrozoan ID 8,& Hydrozoans 1, Hydrozoans 2, Hydrozoan Behavior, Hydrozoan Compatibility, Hydrozoan Selection, Hydrozoan Systems, Hydrozoan Feeding, Hydrozoan Disease, Hydrozoan Reproduction, Medusoids/Jellies (Ctenophores, some Hydrozoans, Scyphozoans): Jelly Identification, Jelly Behavior, Jelly Compatibility, Jelly Selection, Jelly Systems, Jelly Feeding, Jelly Disease, Jelly Reproduction, Fire Corals Lace Corals, Stinging-celled Animals

Hydroids? 10/2/2009
Howdy folks!
What are the critters in the attached pictures? Evil stinging hydroids that will destroy my tank and try to eat my kittens?
<Nice looking cats>
(Ok, I'm being a bit extreme) Or am I lucky and they are something more benign that will leave the kittens alone, and not wipe out my tank. I hope the kittens don't wipe out my tank :)
One of the pictures has my cleaner shrimp in the back to give some perspective. There is a cluster of tubes with brown heads, the tubes are only a few mm long. Would I be so lucky that these are cluster dusters?
<Could be...>
You can find the full size pictures at
<Might be Hydropolyps... but are small, interesting even... I'd leave them on the one pc. of isolated rock. Bob Fenner>


Distinguish Between Hydroids And Bispira Cluster Dusters 9/12/09
<Hi Vivian>
First of all I would like to thank you for this wonderful resource. I have and continue to learn SO MUCH in this great (but addictive hobby).
<You are welcome my dear, glad you enjoy.>
In any case, I have been searching through all your pages, but I cannot resolve this issue. I have little beasts in my LR which, according to pictures from some web sites are described as beneficial Bispira fun worms . On the other hand, in some of your pages you do show pictures of hydroids that look awfully similar to photo 1 (see photo).
<What photo?>
Do you have any pointers on how to distinguish between hydroids and Bispira?
<Hydroids are any of numerous, usually colonial marine coelenterates having a polyp rather than a Medusoid form as the dominant stage of the life cycle. Hydroids have a simple cylindrical body with a mouth like opening surrounded by tentacles. Most species form colonies with individual hydroids branching off from a common hollow tube that is probably used for sharing ingested food.
Bispira are basically a tubeworm and/or feather duster where the "duster" is the crown of a worm that lives in a tube, and it is both a feeding apparatus and a breathing gill.
Hydroids do not have or retract into a tube. I nice pic of a smaller colony of Bispira for comparison can be seen here.
Thank you SO MUCH
<You're welcome. James (Salty Dog)>

Re Distinguish Between Hydroids And Bispira Cluster Dusters 9/13/09
Thank you SO much James.
<You're welcome.>
That is a beautiful picture! From the practical point of view, given that my Bispira or hydroids are so very tiny (I have to get a magnifier glass) that I can not really go through the description with the necessary detail, Do you think that then, an easy way to tell would be to touch the prospective crow/ tentacles to see if they retract?
<Do try, if they are dusters, the crown will retract instantly, revealing the tube..>
As an aside, I HAVE seen these tiny jellyfish kind of thingies beating around the tank ( I do not have a camera good enough to show, but they look like brown transparent umbrella shaped creatures of about
5mm.....I guess that would be consistent with hydroid medusas (no?).
<Can be, dusters/fanworms do not roam.>
all the best,
<And to you. James (Salty Dog)>

Worm ID and pics.   7/27/09
Hello crew!
I've been keeping fish (fresh and salt) for about a year and a half now. I discovered your site fairly quickly after getting into the hobby, and it has been an invaluable resource--thanks for all you do. I also have Bob's CMA book, Bob and Anthony's Reef Invertebrates book, Borneman's Aquarium Corals. I have several other texts, but these are my key references.
Between these and the FAQ's on WWM I've never had a need to send an email to the crew before.
<Welcome to the camp!>
I'm wondering about the identification of a type of worm
I have in my chain of little reef tanks. I'll spare you (many of) the tedious details except to say that the system is comprised of a 20 gallon long that is partitioned into a small settling chamber/skimmer pump compartment, overflowing into a slightly larger refugium with DSB and Chaetomorpha that goes to the surface, overflowing into a ~13 gallon display portion with LR, multiple filter feeding organisms, soft and LPS corals, a purple Firefish, and one fat, happy spotted mandarin. This overflows into a 12 gallon Nano Cube with more rock, soft corals, gorgonians, Corallimorphs, a Wheeler's shrimp goby with tiger pistol shrimp, and a Banggai Cardinalfish. A powerhead in the sump of the cube sends water back to the skimmer compartment to flow back down again. The skimmer is rated for a 75 gallon system and runs about 17 hours a day. I feed fairly heavily including a wide variety of frozen and dry foods, live BBS, and Phyto-feast Live. The system has been established for about 16 months now and has a very healthy and diverse microfauna population including spaghetti worms, (friendly) bristleworms, pods galore, etc.. Even the portion with the mandarin has pods crawling all over the glass at all hours.
There is one worm in particular that has had a strong presence in the tank for some time now that I find very interesting and have not seen in any of my books. I've been through all of the Worm ID FAQ's here now and have found a couple possible matching descriptions and blurry photos, but not enough for anyone to make an ID. I recently managed to get a couple decent photos of one and they are attached.
<See them>
This worm is white with small appendages all over it's body; it has an appearance kind of like a feather boa. Single specimens are maybe .5 cm in length when fully retracted, but can stretch out to maybe 10 times that length. They tend to attach at one end to rock or to macro algae--I first noticed these among the strands of Chaeto in the 'fuge. They stretch out into the water at the mercy of the currents, apparently feeding on suspended organics, and contract every now and then in quick, jerky motions. Then they slowly stretch back out to feed some more . The photos show the worm extending from some c Caulerpa on my blue tuxedo urchin. It's at about center frame, extending to the right of the urchin. It's shown at near full length in one shot, and not quite as near its shortest length in the other. I'm not worried about these guys' presence, I'm sure they're good for water quality and all that , but I am hoping these pictures are good enough to give an ID more specific than "some kind of worm". I was thinking maybe they're nemerteans of some sort, but I'm not even sure of that. Any ideas?
Thanks again for the great site,
Duane Harvey (near Detroit)
<I am strongly leaning to the side of this being a Hydrozoan... Please see here: http://wetwebmedia.com/hyzoanidfaq.htm
and the linked files above... I would try to "tweezer" it out. Bob Fenner>

Re: Worm ID and pics. 7/27/2009
Thank you for the quick reply (original exchange copied below) . I never would have guessed these to be hydrozoans, I'm glad I asked! I have had transient populations of Hydrozoan jellies in the past, and there is a small spot on one of my rocks that intermittently sprouts a half-dozen or so tube-dwelling hydroids, but they have never spread beyond that spot or been a problem so I've left them alone.
<I think this is wise>
The white guys I sent the photos of are solitary, not colonial, and their appendages are randomly placed rather than pinnate or bilateral; those two things threw me, I guess.
<Perhaps I as well>
I said they have a "strong presence" in my system, but that was overstating things a bit. A small but persistent presence is more like it.
I've never seen them close enough to any of my corals to touch them, and individuals seem to come and go fairly quickly. It may be that the Lysmata wurdemanni I keep in the display areas to control Aiptasia are also munching on the hydroids. In any case, I'm not really inclined to go plucking them out just yet, but I'll keep an eye on their numbers for sure--I have been warned. These have been one of my favorite micro-critters in the system since I first spotted them for their otherworldly appearance and behavior.
My nitrates have been unmeasurable (API test kit) for some ten months now, a plague of hydroids seem unlikely to me if I stay on top of things. Of course, I could be wrong...........
Thanks again, and I was happy to see one of the photos made it into the FAQ.
Take care,
<You as well Duane. BobF>

Re: Worm ID and pics. -- 07/28/09
Hello again Mr Herr Sen or Fenner!
<Heeee! Just Bob will do Big D>
I think I have identified the genus of the mystery hydroid--this is getting REALLY fun! It appears to belong to the genus Candelabrum, formerly known as Myriothela. See Julian Sprung's article at:
<Ah yes>
Dr. Ron Shimek covers the genus in his Marine Invertebrates book on page 33, but the photo shows a fully contracted specimen, which is not the state in which one normally spots these things in the tank. After a closer look at those in my tank when fully contracted, the photo is actually pretty darn close. I find his descriptor of "finger-like" projections when extended to be somewhat misleading as well; I think the phrase "worm-like" is a bit more like it. My annoying nitpicking aside , some digging around shows that there is not a whole lot of knowledge on this (mostly temperate) genus, though descriptions of Myriothela in the literature can be found well back into the 19th Century. Some hobbyists have reported plague populations with corals suffering and the hands (or nematocysts) of these animals, while others report only small populations that come and go without incident. Most seem find them as interesting to watch as I do.
If you have any use for it, I can try to remove one from my tank intact and get some pictures of it under a microscope we have here at work.
<Mmm, no thank you>
Thanks, Danke, Gracias,
<D'oh tashi mashiite my friend. BobF>

What is it question 01/22/09 I have posted this on a couple of forums and have gotten various responses. My tank is about 6 months old. I have added rock, sand and frags from several different tanks and locations. They showed up one time and thinking they were aiptasia I used pickling lime on them. <Not aiptasia> They have shown up again and in two different locations so I thought I should ask what they are. <I believe they are hydroids.> They are pretty small, about 1/16 in diameter to give you a scale. Two pics: one is under 20k MH with 460n actinic (darker one) the other is with same lighting with flash bounced in from the top. What is it? <I'm 95% sure they are some type of hydroid (the brown proteinaceous tubes give them away).> Thanks, Steven
<De nada,
Sara M.>

Well done. RMF
<I agree with Sara, these are likely colonial Hydroids, probably family Tubulariidae, possibly even of genus Tubularia or related. Should not touch sensitive corals, may become a pest or simply vanish someday within a short time. Nice pictures with great detail. Thanks for sending. Marco.>

Hydroids? Maybe Not -- Possible Spirorbids? 1/21/09 <Hello there> I have these strange white spots that started on one side of my 125g reef tank and have started to spread across the whole tank, including the LR. I read on another forum that it very well may be hydroids. <Unfortunately, I can't see any individual well enough to determine exactly what you have. They could be the extremely common and harmless Spirorbids (filter feeders) or Hydrozoans. Take a close look at one with a magnifying glass. If it looks like a very small (no larger than a couple of mm) hard white spiral, then it's a Spirorbid. If it looks like a soft white blob with tentacles, then it's likely a Hydrozoan. Please see the following links for more information/photos: Spirorbid (see photo on the right at FAQ titled 'Oh Mich.... ID Spirorbis spp. and possibly Collonista spp. -- 09/29/07"): http://www.wetwebmedia.com/snailid12.htm Hydrozoan (see FAQ titled 'Help identifying 2 pics? 06/21/08'): http://www.wetwebmedia.com/hyzoidf5.htm I have had coral, Zoas and mushrooms, for about 6 months. I have attached links to the photos. If it is hydroids, I have read that tear down and sterilization is the only way to eradicate them. Am I, and my coral, doomed? <Not necessarily! Let's first confirm exactly what you have and go from there!> http://s488.photobucket.com/albums/rr249/mantisman51/?action=view&current=hydroids003.jpg http://s488.photobucket.com/albums/rr249/mantisman51/?action=view&current=hydroids001.jpg <I'm hoping that you do indeed have Spirorbids instead of Hydrozoans, but if not, let me/us know. Take care, -Lynn>


Brown Plant Growth 11/27/08 I have a 300 Gal reef, established over one year, lightly stocked. (3) 400 Watt 10K MH, all parameters look good. This brown plant growth on the rock comes and goes in cycles every two weeks or so. About 1/2 inch growth, with fine thin leafy tops. I brought a sample to the LFS, they could not find any critter who would eat it. Thanks, Steve <Hmm... I could be wrong, but these look like hydroids to me. http://www.wetwebmedia.com/hyzoanidfaq.htm Best,
Sara M.>


Deep Water Coral Identification 11/16/08 Hi There. I was wondering if you guys would have any insight to what kind of coral this might be? I was fishing off of the Florida Keys where I live. We were fishing a large hump that comes up from 1300 ft. to about 600 ft.. On top of this hump we snagged this big coral on our line, which we thought was a fish at one point. when we got if to the surface It was something I have never seen before. I work for a company down here which supplies Caribbean life to zoo's and aquariums all over the world, and it has stumped everyone. <I do think it must be a hydrocoral of some kind. A close-up pic of the polyps would make it easier to ID with more certainty. I would also be careful not to be breaking the law here. If it's a protected species, it might get you into trouble taking it home... but I'm sure, with your job, you know about all that. :-)> Any suggestions on whit it is and maybe the best way to try and keep it alive? <If it is indeed a Hydrocoral from 600ft then it likely doesn't need much, if any, light. It will need quality feeding... they are not too difficult to care for if they were healthy when you get them (which this one appears to be). Best,
Sara M.>

Hydroid, ID, control...   11/14/08 Hello all! <Mariusz> I was hoping you could give me an ID (ie. scientific/common name) on this Hydroid. It was taken from: http://www.wetwebmedia.com/hyzoanidfaq.htm (i have also attached the same pic). I have a bunch of these in 120 tank with about 140lbs of live rock. <Mmmm... can't tell the species from this small pic> I recently took all fish out of the tank to let run fallow after a parasitic infest. Most corals have been removed (for other reasons). All that is left are a few mushrooms and leathers, peppermint shrimp, hermits. The tank has been running fallow for 6 weeks now and I'm in no rush to put my livestock back in. Also for 6 weeks I haven't put any food in the tank either, it's just been running with Deltec skimmer (which hasn't produced much as I have almost no livestock and no feeding). So questions: 1) are these hydroids a danger to fish? not sure how potent the sting is. <Could be... if they're unaware, get too much exposure> 2) How can I rid these with out manual removal as I've been trying for almost a year. Not sure if these guys are worms of some sort and if de-wormer will work, possibly Prazi or other. Is there any biological alternative? Without proper ID its been difficult moving forward towards a solution. Thanks <Can be very difficult... frustrating up to the point, extreme, of making it reasonable to bleach/kill all LR, start over with some new LR material placed over, amongst, using the killed rock as base... Otherwise, you might be lucky to discover a predator (perhaps an Opistobranch...), but even here, they wouldn't eliminate all... "So many chickens, so many foxes"... Bob Fenner, who would bleach, nuke>

Re: hydroid 11/15/08 I've attached 2 pics of these hydroids (pulled out of the aquarium and place them on paper). Is it possible to identify them now? Are they some type of worm? <Mmm, much more likely tube snails... though could be Sedentariate Polychaete worms... You can tell if/when they're "open" underwater> Will Prazi or some type of anthelminthic work? Any suggestions besides nuking my system? Thanks once more <Mmm, I'd ignore them... not deleterious... you could likely get a crustacean that would predate these... I would not use chemical controls. http://www.reefs.org/library/aquarium_net/0897/0897_8.html Bob Fenner>

re: hydroid... snails  11/15/08 Thanks for the link. However, the link describes a mucus string/web produced by these worms but there is no mention of sting. I've had mushrooms die and retract if they are touched by these strands. <Surprising...> Would these strands have some type of sting? <Not as far as I've ever run into> The link describes animals larger than the pics I sent. Animals in my system have diameters of 1mm or less. So I take it they are not hydroids? <Not hydrozoans, Cnidarians... are Mollusks, Gastropods. B>

re: hydroid 11/15/08 I'm in complete agreement with you after further surfing...just have to figure out why the mushroom died and why any softy kinda retracts when the mucus strands are out. Perhaps its something else I haven't noticed. I'll be keeping a close eye. Thanks for all the help! <Certainly welcome! BobF>

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