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FAQs on the Hydrozoan Identification 8

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 6, Hydrozoan ID 7, & 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

Red algae ID     2/11/18
Hello, I wrote in many months back and you were super helpful identifying some algae for me. I hope you can help again! I have attached a photo of the reddish pink tree-like algae that is spreading like wildfire through my tank. I didn’t see anything like it in your algae ID archives... can you tell me what it is?
<I wish I could... the regular branching... I don't think this is an algae/Thallophyte, but a very pink Hydrozoan of some sort>
Does anything eat it that I could use to help control the spread? Thank you!
<There are some notable Seaslugs that ingest various Hydropolyps, but I don't know anything re this particular one. I would remove it from the system, as it may be producing stinging elements that will bother your other livestock. Do you have a microscope with a USB connection? I'd like to see some 100-200, 400 time magnification shots. Bob Fenner>

Re: Red algae ID      2/12/18
Hi Bob, I don’t have a microscope unfortunately.
<Perhaps a local fish store does, someone from a marine aquarium club>
I have tried some manual removal but ripping it off leaves traces behind that I cannot remove, and it is widespread, including my tank overflow box and powerhead. It also grows very very fast.
<Yeeikes! I wish I could tell definitive what this is. I have never encountered something this shade of pink, nor with the array of branching it shows>
Is bleaching my tank and starting over my only option to eradicate this pest?
<It may well be>
Also, can it sting fish or just corals?
<Can't tell w/o testing or microscopic looking. BobF>
Thanks again.

re: Can't ID hair like growth in reef aquarium(SMALLER SIZED PICS)     9/6/17
Mr. Fenner
Here I bought a stereo microscope and took pictures of the pictures of the hair like growth being told. Hydroid digitate, Bryozoan Bryopsis, algae of unknown... Can someone please help me now??
<Mmm; well the color, strands remind me of algae... are there cell walls in the strings? That is individual cells making parts of the strands? If not, perhaps a blue green "algae". The expanded tips remind me of the ciliate Vorticella... how big are these? Could be a digitate hydroid, but so green?
Sorry, can't make out more here. Bob Fenner>

re: Can't ID hair like growth in reef aquarium (SMALLER SIZED PICS)     9/6/17
Some are 1/4" some maybe 1" but they come back quick...
<Umm; these are digitate hydroids... I'd be removing them>

Let me mess with the new Gadget it says up to 600x. I just held it with my hand and focused as best as I could I'm going to suction it down to a piece of glass I did add some distilled water to it I pulled it with tweezers from the base I
was hoping you could identify it by the circle tips at the ends of the object it looks like a red blood cell but green this is what they look like at there latest like largest... 1" tall Max. Look white not matter if I use a blue flashlight or if I use a white flashlight they look the same until I pull them out of the water then they are green right away I don't know if it's the oxygenation or if they're just green and look white but they have no feeding response when I feed my Montipora wouldn't a did you take hydrated have a feeding response to Reef Roids or Coral Frenzy or even Cyclops I see no change in anything actually the ones that have peaked in size have ingrown no more but if I were to pull them off or toothbrush them they would come back not as fast like tall wise but they come back on the Fred I brush them off when they were very small and within two days they're still back to their very small stage of maybe one 20th of an inch did you take my droid have a feeding response to reef Roids or coral frenzy or even Cyclops I see no change in anything actually the ones that have peed in size haven't grown no more but if I were to pull them off or toothbrush them they would come back not as fast like tall wise but they come back on the Fred's <?> I brush them off when they're very small and within 2 days there they're still back to their very small stage of maybe 1/20 of an inch. ..
<Pull the affected rocks out... dry>
if I can't figure this out I'm going to trash the library and then quarantine all my coral into a small 22 gallon frag tank because I'm worried that if I toothbrush this stuff off put them into a new tank it will just start the process all over again even though I'm using dry live rock next time or maybe I will just frag pieces of SPS that don't have any
near it but it's the track of philia that I don't know if it has these things on the small base underneath they don't grow on any fleshy Parts only on hard surfaces except glass... I noticed them growing on my overflow wall there is none in my refugium skimmer compartment because which is weird I have a 300 watt Mars light and a macro reactor and a CFL light growing some red color for red kelp tree like red grapes growing on a vine None but in the display...
<Thank goodness>
If I can't figure this out I'm going to most likely have to throw away a lot of corals that I've been nursing back from that product vibrant liquid aquarium cleaner and caused my anemones to basically shrivel up and it did nothing to this stuff after five doses I will try to get a better photo more detailed of the cell walls I mean the box of this microscope stereo microscope shows this thing looking at organisms not just maybe that's the picture I took of this stuff was maybe 40-50 X I mean looking at a hair is not that impressive when it advertises 600x maybe it's the distance I had it at it was too close Maybe I know it wasn't too far away... Just another question I bought some live rock drive from BRS.
<... see others opinions.>
The curing process. Just sit in barrel for few months small WC every week maybe and when no nitrite there ready? But how long do u leave em in there so there actually live and not just the decay wearing off and no po4 leaching.,. Also when I start so I have to seed with i.e. Biospira or an alrdy cured LR (NOT ONE OF MINE) even though some have these things on them while some but taking the risk isn't my biggest thing. I notice they don't sting cut irritate the sps and stunting growth. I have my macroalgae reactor running now and I also reinstall my algae Turf scrubber which the vibrant aquarium cleaner people told me to take off line so I'm hoping after that I've already
noticed a tripling of my Chaeto that I put in there a very small amount that you twist tie onto the plates and I'm also going to reinstall a new UV light I haven't had a UV running for about 8 months now but I think a recent tail rot and a Popeye incident in two separate fish I think UV would not be a bad thing
<Is a good thing>
and maybe when I toothbrush these things off it might stop the spreading of these or regrowth because the spores if any will die once they go inside the UV chamber fingers crossed thanks for your response and if you could please reply about the live rock curing that would be great thanks again you guys are wonderful for taking the time to answer regular folks like me that sometimes the answers might not even be there ever.
With much appreciation
Matt Macri
<Welcome to my input. Bob Fenner>

re: Can't ID hair like growth in reef aquarium (SMALLER SIZED PICS)     9/6/17
What about taking one rock out... Putting in a bucket of tank water with heater and pump... Cover it dark for three days and see if it dies..
<Mmm; not likely to die this way; but go ahead and try it>
How long can you dark out a tank safely without killing Coral?
<Depends, but likely the corals will die at about the same rate/exposure>
Ppl do it for Bryopsis etc.. I can hammer a piece of rock that the top half has the largest strands of this stuff.. it's a large branch rock with s large green Monti growing from a small ledge in the middle of it.. I was thinking of
basically halving it and black it out for 3-4 days and if it kills it.
It's an algae and I should do it to my whole tank....
Your input?
<Physically systematically removing, scrubbing off (and rinsing) outside the tank is my fave, direct approach... There are folks who advocate chemical means of burning, sealing... There are some potential predators including Nudibranchs, Seaslugs, Urchins, possibly fishes (e.g. dwarf angels) that might consume this pest>
I've never had a pest issue in 2 years I always found natural remedies like Emerald crabs or Turbo snails are sea cucumbers to keep mice and overturned or Nassarius snails to do the same thing bristle worms to eat overfed food always having a quarantine tank at Bay in case something happens always not being cheap on equipment even though I'm on disability but I save my money rather than buying cheap stuff I buy the good equipment this way it doesn't break or electrocute me or there's all kinds of stuff that can happen but I also buy a backup that's less expensive just in case... I just don't want to have to somehow take my fish somewhere else to a fish store which I can't monitor mean for all I know they could be breaking out and diseases and dying cleaning my tank out putting my Coral in a small frag tank with an acrylic box filter and basically scrubbing my tank with water and bleach and then scrubbing out my sump as well..
Done cycling my tank curing my live rock which isn't going to be new dry live rock once it's cured I have to re cure it so there's no phosphates linking or put it in my tank fish only for a month or two while the phosphates Leach out and then put my corals back in my tank once the phosphate start reading zero again that's a very very long and tedious process and I would have to find a place for all my snails crabs cucumbers pet shrimp of many sorts but I have a quarantine tank that is medicine free I could just add a few of the bad live rock in there to give them places
to hide and just Neil
throw some food in there once in awhile some algae Wafers some other kinds of food just to keep him alive and sand on the bottom for my Tigertail cucumbers one is almost 2 ft long and the other is about 10 inches and I definitely don't want them to die them are one of my favorite things to look at when they come out
<Bob Fenner>
re: Can't ID hair like growth in reef aquarium (SMALLER SIZED PICS)     9/6/17

What if I remove the affected rocks couldn't I significantly lessen my biofilter
<? I wouldn't remove the rock permanently... Just to scrub/clean it. B>

Hydroid ID and control       5/4/16
Hello WWM Crew,
I have noticed a great deal of what looks like some kind of stringy white algae growing in the darker, lower flow section of my large reef tank (under shelves and overhanging rocks, etc.).
<Mmm; no; these are Hydropolyps; not algae>
I didn’t think much of it, but I noticed recently that previously happy Zoanthid colonies are now staying closed most of the day, and longer spreading or fluorescing nearly as much as they should. It appears the two observations may be related, as I can see a few of these same stringy, branching, algae-looking structures extending up through the affected Zoanthid colonies. On closer inspection, I can see that the stringy hairy things have what looks like a feather duster fan or even a tentacled polyp. I’m starting to believe that they’re a type of hydroid, and am wondering if there’s anything I can do to stop them overtaking and killing my beloved Zoas.
<Sure: Read here: http://www.wetwebmedia.com/hyzoancompfaq.htm
Below is a photo of some of the culprits — I believe the span of the tentacles is less than 2mm, on average. I’d be grateful for any help in ID’ing the species,
<Mmm; see WWM re Hydrozoan ID>
as well as any suggestions you might have on how to reduce their proliferation.
<Welcome. Bob Fenner>

Something Odd on my Green Star Polyps       11/23/15
Hello WWM:
<Hey Will>
Thank you for what you do for the hobby.
I have had a green star polyps frag for about 6 weeks. I am new to the hobby, running a 92 gallon corner tank that was a hand me down. I have a 25 gallon sump, UV sterilizer, media reactor running NPX BioBalls, and a sea Urchin skimmer.
My GSP is attached to two small LR branches, along on a LR shelf. The LR is the kind that LFS sells that was made in California and is synthetically impregnated with the LR bacteria - not a lot of likelihood of hitchhikers.
About 10 days ago I noticed one or two small flowery looking things that come out when the lights go out and the GSP recedes. People online have theorized that it is aphasia. Or algae.
<No; looks like Hydrozoans.... perhaps Myrionema genus by name. At any length you can use this to look up re on WWM, elsewhere>
I have taken it out in an effort to tweeze it away, but only got a small piece. I also see many new little white conical sponges on the frag mat. There or some of these on the other side of my tank as well. I have attached one high light and one low light picture of the GSP.
Are the sponges bad? Are they bad in the tank? Do you have an opinion about the "stalk" coming out of the frag?
<Sponges not likely bad>
I cleaned my sump last Wednesday, when I did see one Aiptasia (no doubt about it) and I removed the carbon filter bag that it was attached to. I am thinking of getting rid of the whole frag, unless you think this is a benign thing on the GSP.
<Not benign; unfortunately. Read on!>
Thanks and Happy Thanksgiving!
<And you, Bob Fenner>

Re: Something Odd on my Green Star Polyps       11/23/15
I will remove the frag at once. Is there any chance that it has not spread throughout the tank? Or am I doomed?
<There is a chance; and you're not doomed. Sheesh. BobF>

Look what I found        8/26/14
Found this on the beach this morning. Though at first it was plastic but when I picked it up it felt real. Any ideas
<Ah yes; a remnant of a colonial Hydrozoan: Velella. BobF>


Help with Identification Please       8/1/14
I’ve really been struggling with getting a legitimate identification of this particular “thing” in my aquarium. I’ve provided three photos, one you’ll be able to see is growing from a rock, the other is scaling the back wall of my tank.
I’ve heard everything from hydroids, Foraminiferans to bryozoans. Any thoughts? Good or bad?
<These are almost certain stinging Hydroids... undesirable. You can read re their control/removal on WWM. I would siphon while snipping...>
Thank you in advance,
Dustin Betterly
<Welcome. Bob Fenner>

Re: Help with Identification Please       8/1/14
Do they spread?
<Some species more than others... very common group of organisms on the world's reefs>
I pulled them with my fingers and felt nothing, but
maybe I wouldn't, not sure.
<Some more stinging, stickier than others... folks fingers, hands are callused... Don't touch around your eye...>
I've checked out the WWM and I find it a bit confusing. I'd prefer to
not nuke the tank if possible.
<I wouldn't over-react; do this>
Some people have said that since the
tank is so young they might disappear on their own. Just looking for
some answers.
<... Ask better questions. B>

Odd flower like object on live rock, green and very tiny   2/1/14
I found the attached object on my live rock recently and cant figure out what it is, even after hours of Google searching, including your site!
<Mmm, looks Polypoid... My guess is on some sort of Hydrozoan... Does it "sting", stick to a sensitive part of your wrist? Yowch!>
The live rock I bought only stated that it is usually from the South Pacific but could be from anywhere.
The object is ridiculously small, maybe 1/4" high and a few mm wide. It doesn't come off the rock with a baster like algae (I do have diatoms and GHA). I originally thought it was a new strand of algae.
I have asked over at Nano-reef forums but the only idea I got was that it could be some sort of macroalgae. This tank has only been up for about 6 weeks and currently only has live rock in it.
I have only noticed this one in the tank and it's stationary, I haven't noticed if it looks any differently at night than during the day. My apologies that the pictures aren't better.
<Welcome! Thanks for sharing. Bob Fenner>

Re: Odd flower like object on live rock, green and very tiny   2/1/14
Thanks Bob, I've never touched it so not sure if it stings! I'll see if I can trick my boyfriend into finding out...
<Heeee! Good idea... the wrist, not callused hands or fingers. BobF>

Coral identification    4/14/13
My LFS had some corals on sale so I decided to pick some up but they didn't have names or labels attached to them. Could you please help me with the identification?
<Mmm, can guess... the first and last (the two w/ stony skeletons) are Mussids of some sort... maybe Lobophyllia/s... the other (sans hard parts) appears to be some sort of Zoanthid... see WWM re these... can be problematical for other Cnidarians and humans>
 Also what is that arm coming out of the green one?
<Can't quite make this out. If it's still there, send along a bit larger, well-resolved image... otherwise, it looks to be some sort of trailing mucus>
 It would make my life easier if they were better at labeling the stock :(
I also picked up a chunk of live rock and much to my surprise it came with a small Lawnmower Blenny!!! I was doing some reading on this fish and it sounds like they can nip at corals.
<Mmm, not usually though. Are very "in" to types of algae>
 Beside the 3 in the pictures I have a Kenya Tree coral, 1 Green Hairy Mushroom and a small Frog Spawn frag. Are these at risk from the blenny?
<Not likely; no>
One more concern I have is what to stock in this tank. I have been reading over the site (haven't gotten through it all yet) trying to figure out what the most hardy, colorful fish that i could put in there. Most common angel and butterfly fish seem to be out. Could you offer any suggestions of some families of fish I could research or is this on wet web and I just haven't found it yet?
<Mmm, likely a good idea to urge you to read here:  http://www.wetwebmedia.com/RfLvstkgF15.htm
and the linked files above... you'll find plenty in your own searching here>
There is so much information out on your site and the web that is gets confusing when everyone has an opinion on what will work and what wont.
<You can trust what we offer>
Thanks so much for your help!
<Welcome. Bob Fenner>

Re: Coral identification    4/14/13
Here are some more pictures. Best my phone can do since my wife took the fancy camera with her on vacation.
<Ahh, and am wondering... these now appear (more than one... see the ones lower, on the left side?) to be hydrozoans... I would carefully brush these off (outside the tank) w/ an olde/soft toothbrush... You don't want these to proliferate in your system. BobF>

Re: Coral identification      4/15/13
Yes I was talking about the Hydropolyps. Sorry should of been more clear.
I was reading over the Hydrozoan FAQ but I didn't see any pictures that match what I but at least I have a better understanding of what I am going against in case I didn't pull the frag out in time. Your team as amassed such a wealth of knowledge on this site I wish I had time to read it all!!!
I read through the thread that you sent me in your first reply and I think I have a suitable list of livestock just need to do more research as to who gets along with who!!
<An adventure for sure!>
Thanks so much for your help!
<Ah, welcome. BobF>

Identification help 2/5/12
Hi Team
I recently noticed these critters on the walls of my refugium. I haven't noticed them in the display tank. The tank is now 5 years old, a mixed reef, and doing well. I have enclosed a couple photos:
<Nice... Jellies galore!>
There are several small hydroid type creatures attached to the wall and can be seen in photo 1.
<Yes... are Medusoid stages of Hydrozoans...>
Along with them I noticed this tiny umbrella shaped creature which is free-swimming. It quickly pulsates and almost looks like a tiny jelly-fish. It can be seen in both pictures. Any thoughts?
Thanks a bunch
Carlos D.
<Mmm, I'd be doing what you can to limit their reproduction, presence.
Please read here: http://www.wetwebmedia.com/jellycompfaqs.htm
Bob Fenner>

Re: Identification help 2/5/12
Thanks Bob! Appreciate the help. Presently only in the refugium so I will keep an eye on things and if need be I guess i can take the refugium off-line and clean it out and start over.
<I see>
thanks again
<Welcome Dr. C. BobF>

Identification 10/25/11
Hope you can help ID this! It has long white tentacles that have a fan looking attached. The tentacles look spider web thin and retract when the lights come on. They grow out of a sac looking thing that looks like it can attach to anything. The first picture is of the sac and the second is of the tentacle.
<Appears to be a hydroid/Hydropolyp of some sort. See WWM re. Bob Fenner>

re: Identification 10/25/11
Are they good bad harmful.
<? What is it w/ people? READ: http://wetwebmedia.com/hyzoancompfaq.htm
DON'T write. B>
It almost looks to have a jelly sack and a long string like thing coming out tank is full of them at night when lights are out, when your yurn lights on you can watch them retract there arms.

Filter/Suspension Feeder I.D. 10/4/11
Good Morning,
<Threeish in the PM here in Fiji presently. Bula!>
I have a curious animal that has recently taken up residence (become prolific) in my little reef.
I have attached an image:
<Mmm, nothing attached>
Demonstrating it's unique (to me) means of increasing its colony(?).
Regarding its behavior: As far as I have observed over the weeks since discovery, the animal(s) are benign, and appear to be very simple suspension feeder (worm?) that spreads via filamentous thread that produces a fan type filter evenly along it's length. They (it) is easily removed with light scraping of the glass. It is most evident on the glass wall, however, it is present on most surfaces via the filter. It appears to double it's size every few days.
As for the environment that I provide: I have made great effort to mimic natural reef/lagoon I saturate the water column with fine particulate food in hopes to foster growth primarily in my stony coral colonies, secondly in my burgeoning sponge population. I assume that has benefited all suspension feeders .
I hope you could help me with identifying this bizarre (to me) animal, and at the least point me to a resource.
Best Regards
Ronald E. Tibbetts
<Please do send along a well-resolved image. Bob Fenner>
Re: Filter/Suspension Feeder I.D. 10/5/11

Even after all these years you can't just drag and drop an image into an email.
<Ah yes (no). I take it you're seeking the ID not of the cucumber above right, but the net-like mass attached to the wall... This looks to be some sort of Hydrozoan... I would be wiping this off and vacuuming out as much as I could. Too likely stinging to be comfortable. Please read here:
and the linked files above if you'd like more related input. Bob Fenner>

Feather-like Filaments on Trachyphyllia 10/2/11
Hi WWM Crew! I have an Australian Trachyphyllia at the LFS I currently work at which has some type of feather filaments attached to the outer part of its tissue, toward the skeleton.
<I see these... Hydrozoans/Hydropolyps>
I have never seen this before and would like some assistance in identifying it. I believe it is some sort of worm or other hitchhiker that extends feather-like tentacles for capturing microfauna (similar to Feather Dusters and Porcelain Crabs).
<Similar, but more deadly... not just physical, but stinging, agglutinant>
The long feathers stretch out then will quickly retract to its point of origin and will then slowly extend again. I have attached some pictures and a link to a short video to help explain in better detail.
http://s351.photobucket.com/albums/q449/MarineScene/trachy%20video/?action=view&current=MVI_9342.mp4, sorry for having to turn your head to properly view the video, I forgot that I can not rotate video from my PowerShot camera. Any help is appreciated and thank you for a great and informative website that I use quite frequently!
Thank you,
<Let's have you start reading here:
Perhaps the linked files above. Then write me/us back if you have further concerns, questions. Bob Fenner>

Micro-invert ID 6/28/2011
Good afternoon, crew,
I have just recently seen several of these little dudes in my 'fuge. I have searched to the darkest end of the web (may have missed a spot or two), and am clueless. Although I have NO idea what they are, they are fascinating little creatures. The "tail" appendage telescopes from about 5mm to 50mm and retracts again, leading me to believe it is a feeder arm of some sort. The main body is about 2-3 MM in length.
Can you give me a vector, Victor?
<I do think you have a Hydrozoan/Hydropolyp species here... I'd vacuum these out. Stinging if they get into your main system and eating you refugium production where presently encamped. Bob Fenner>

Re: Micro-invert ID 6/28/2011
Thank you. Since my email, I've counted at least 10 so far in my fuge.
Going to be fun getting them all out of my Chaetomorpha!
<Might I suggest a bit of rigid airline tubing attached to the airline as a siphon? BobF>
Re: Micro-invert ID 6/28/2011
Exactly the set-up I used to siphon off the red-brown Planaria that went nuts in my tank earlier. Works very well. I'm a bit more concerned about actually finding all the little freaks hidden in the Chaeto. Maybe remove and rinse it all?
<Worth trying. B>

What is this, and how do I get rid of it?
This came as a hitchhiker on a frag from a LFS and it has now spread to plague like proportions. What is it, and more importantly, how do I get rid of it?
<Mmm, Hydropolyps, Hydrozoans... read here: http://wetwebmedia.com/jellycompfaqs.htm
Thanks for the info. I love this website. You guys are doing such a great service donating your time and knowledge. Thanks.
<Welcome. Bob Fenner>

Critters on Glass, 1/12/11
Hi Crew!
I was wondering if these are tomont cysts attached on my aquarium glass.
<Are not, the cysts are not visible to the naked eye.>
These were the best pictures I could take. My tank is fallow right now but wanted to know if I should knock these off to be sucked up through my filter.
Thanks for the info.
<Looks like they might be hydroids,
http://www.wetwebmedia.com/hydrozoans.htm .>
Hydroid Jellies 1/12/11
Hi Crew! I was wondering if these are tomont cysts attached on my aquarium glass.
<Mmm, no. These are very likely Jellies, Hydroids. See here:
These were the best pictures I could take. My tank is fallow right now but wanted to know if I should knock these off to be sucked up through my filter.
Thanks for the info.
<Mmm, they'll likely "disappear" of their own accord in time (days to weeks). If there are only a few I would not be concerned... If numerous, they might sting your purposeful livestock. Bob Fenner>

Re: Critters on Glass, 1/12/11
Thanks for the info but these are about the size of the head of a straight pin or the dot of a pen.
<I would still bet on them being hydroids.>
This is a very close close-up of the "thing" in question. Never had them in my tank before until I had an Ich epidemic...
<Unrelated except that the tank being fallow probably allowed these to propagate a bit better than before.>
hence the fallow tank. I'm thinking it's something I should continue to get swept out but I didn't want to try if they were say copepod eggs, amphipod eggs, good things.... would love to know what they are.
<Not something I would be overly concerned with, can be removed if they bother you, but you will not most likely get them all.>
Re: Re:

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