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FAQs on the Ctenophorans, Scyphozoans and Hydrozoans: Jellyfish Identification

Related Articles: Jellyfishes, Scyphozoans, Hydrozoan Jellies, Hydrozoans, Cnidarians,

Related FAQs: Jellies 1, Jellies 2, Jelly Behavior, Jelly Compatibility, Jelly Selection, Jelly Systems, Jelly Feeding, Jelly Disease, Jelly Reproduction,

Salt water critter ID    7/22/19
Aloha, Mr. Fenner and staff, I have a 125 gal saltwater tank. The tank has been up and running for almost a year. I have a very little clean-up crew and have added four corals to the system about 1 month ago. yesterday I noticed little white pinhead dots on the tank glass. They do not feel hard and have tentacles (?) that move with the water flow. I did have a white cloud algal bloom that was taken care of with a few small water changes, but other than that all of my water qualities have been spot on. please see the attached photos. Thank you for all of your help. Michelle Nason
<Looks to be some sort of Medusoid life... Hydrozoan, Scyphozoan Cnidarian or Ctenophore; likely strobilation from part of the hard structure of your new corals or live rock. Not likely problematical; will be sifted out by your mechanical filtration. Bob Fenner>

Re: Salt water critter ID    7/22/19
Thank you very much.
<Welcome Mich. BobF>

Critter I'd? Help!       4/23/15
Hello! Kathy here once again. Thank you for all your awesome advice in the past and I am once again in need of your expertise. So I have noticed these REALLY long white tentacles sweeping all over my frag tank. When I took a
closer look, it looks like these long tentacles are actually coming from these tiny little slimy / jelly blobs all over the glass. These little blobs are stuck pretty flat all over the glass and protrude these really really long tentacles and each of the long tentacles have smaller little tentacles all throughout kind of like teeth on a comb. I have searched everywhere and the closest thing I could find are the comb jellies
<Ctenophores was my guess thus far; perhaps Hydrozoans>
but I'm not sure if that's what it is. They are reproducing really fast and there's at least 100 of them all over the glass and you can see the tentacles all over the tank. Are These guys safe?
<Maybe not>
How do I get rid of them?
<Need to know what they are; but likely scraping, vacuuming and netting out after scraped>
Please help!
PS each little blob looks just like a little wiggly blob. Not at all like the comb jelly in Google images. Thanks again.
<Please send along a well-resolved pic. Bob Fenner>

Re: Critter I'd? Help!        4/24/15
Hi again. I've been trying to get a good picture but can't right now. When I get home later I can take a picture with a better camera. It's basically a clear jelly like body with white inside and it's kind of divided in half.
This is a handwritten picture of what I see. Thanks again.
<Mmm; am changing my best guess to this being some sort of Hydropolyp (Hydrozoan)... most likely undesirable. BobF>
Re: Critter I'd? Help!

Hello again! After lots of research I am leaning more toward ctenophores. I was able to take a few out. They are actually green in color. It's AMAZING how LONG the sweeping tentacles are. Here's a pic. Please tell me what you think. Thanks again.

Re: Critter I'd? Help!        4/24/15
Sorry or the bother, this might be a better pic.

Re: Critter I'd? Help!        4/24/15
Last picture I promise.
<Still too blurry>
Now my question is, do you still believe they are ctenophores? Are they harmful to corals? How do I get rid of them?
<See prev. emails>

Thanks in advance for all your help. I moved all my corals out just to be safe but would really like to be able to place them back in as soon as possible. Thanks
<Might be a Hydropolyp species... Not likely compatible. B>


Jelly-Like Organism Identification Help    6/8/12
Dear WWM Crew,
Today I noticed a sizable number of tiny jellyfish-like organisms in the sump/ outflow chamber of my 32-Gallon Finnex M-Tank. I haven't added anything in over a full calendar year and it was established as a reef tank nearly five years ago.
<Mmm, not uncommon... likely strobilized off the live rock... natural reproductive event>
 Additionally, I just moved the tank to my new place three weeks ago and everybody seems to be doing very well. Some of the organisms were "swimming" around in a manner reminiscent of a jellyfish's while others were adhered to the glass surface, although they also would "swim" upon being disturbed. I sucked a few of them up into a pipette and pipetted a droplet of tank water, the diameter of which was a bit larger than that of a quarter, onto a plastic 1 Gallon Ziplock bag which was laid over a red piece of paper to make these clear organisms more visible (please see the attached image and note the printed logo letters as a size marker). What do you think they are?
<As you state; some sort of Medusoid life... Hydrozoan, Scyphozoan Cnidarian or Ctenophore>
My guess was some sort of Hydrozoan or Scyphozoan, but I though I would ask an expert. Also, do you think I need to be concerned about them?
<Not likely, no... will probably be mechanically filtered out...>
Thanks for your time and help and I look
forward to hearing from you.
<Oh, do read here: http://www.wetwebmedia.com/jellyidfaqs.htm
Bob Fenner>

Re: Jelly-Like Organism Identification Help    6/8/12
Dear Mr. Fenner,
Thank you for taking the time to answer my e-mail, I do appreciate it. Also, I actually read that page prior to e-mailing you, which I then used to make my amateur ID attempt. Many of the photos posted on the link you referenced (http://www.wetwebmedia.com/jellyidfaqs.htm ) had similar qualities but they also looked a bit different, so I figured I would send my own e-mail. Anyways, thanks again for the opinion and your pages on WWM have been very helpful as always.
<Welcome. BobF>

Identify 10/15/11
Saw this on the glass today and all over the overflows. Hope you can help with identification. Thanks
<Mmm, appears to be... soft bodied, radially symmetrical... a "jelly" of some sort... Read here: http://wetwebmedia.com/jellyidfaqs.htm
and the linked files above. Bob Fenner>

Colonial Anemone/Parazoanthus? 12/22/10
Hi Crew,
<Howdy Jim>
So far I have had my tank (29G reef) set up for about a year now. Despite some algae and pH problems which I'm working to get in-line everything seems to be doing well. I have used your site for a reference for the past year and so far it has been a great resource and I haven't had to ask any questions directly up until now (thanks!).
It seems that every week or so I still notice something new in the tank.
Lately I have seen 3 colonies of these "polyps" in my tank. From some research on your site and elsewhere, the only conclusion I can come up is that they are some kind colonial anemone or Parazoanthus.
<Mmm, am pretty sure these are Aiptasiids... the family of Glass Anemones.
Please see here:
They don't seem to respond to changes in light like a tube worm, although when I prod them with an object they seem retract into their rigid tube. They are only a few mm wide and long.
<Oh! Small thus far>
Do you believe these will become a problem if they start spreading throughout the tank?
<Could be if they begin to squeeze out other life, perhaps stinging your livestock>
Should I remove them, or just monitor them for now?
<If not too numerous... I'd just watch/see. Do see the related links above the citation re controls of various sorts>
Please see attached photo.
<Welcome and happy holidays. Bob Fenner>

Re: Colonial Anemone/Parazoanthus? 12/22/10
Hi Bob,
<Hello again Jim>
Thanks for the prompt response! I had thought they might be Aiptasia at first, but from my research I thought I remember reading somewhere that these creatures don't retract into a tube, but when they retract, they usually retract their whole body into hiding (making them hard to get at).
<Yes and yes>
The ones in my tank definitely leave a visible tube behind after retracting so it is the only thing that made me doubt they were Aiptasia.
<Me too if so>
I will monitor and take action if necessary.
By the way I have a copy of your Conscientious Marine Aquarist and found it also to be a great resource. I wish I would have just followed your advice from the book regarding the size of the setup. I think a larger tank would have just been easier from the beginning (despite the objections from the wife!).
<Heeee! Woulda coulda shoulda. Perhaps a "trade of sorts" w/ your spouse.
Is she opining re something she'd like...?>
Happy Holidays and thanks again,
<Oh Jim! These may well be Hydrozoans/Hydropolyps based on morphology, size, tube-dwelling habit and withdrawing behavior. And to you and yours. Cheers, BobF>
Re: Colonial Anemone/Parazoanthus? 12/22/10
I hope not!
<Heeee! If fishes were wishes, we'd all have full tanks!>
I even thought about Hydroids; I just wasn't aware that they also could withdraw into a tube. They are definitely colonial in nature and so far I see three colonies in the tank, with this and another appearing most recently. The third has been around for at least two months and has about 12 members.
<Mmm, but not in one patch/batch...>
For what it's worth, I was taking a look at them again and I noticed some worms and even my peppermint shrimp touching the polyps (causing the polyps to retract) and none of the animals involved seemed to recoil in pain.
They also don't seem to be connected like I have noticed in some other hydroid pictures but I'm not sure if this is a prerequisite or not.
<Solitary Zoanthids are rare>
I only came to the conclusion that it might be some kind of Parazoanthus because the tentacles seemed to be long and "stringy" as compared with some of the other pictures I've seen of that genus. Then again many Hydroids seem to share this trait as well.
I will definitely keep an eye on them. Thanks again. You and your crew do an awesome job.
<Glad to share. BobF>

Re: Colonial Anemone/Parazoanthus? 12/30/10
Hello again Bob,
<Hi Jim>
After a little more investigative work, I think I may have found what these creatures are (at least narrowed it down a bit).
I first found something that looks fairly similar (although not exact) on this link here: http://www.masa.asn.au/masawiki/index.php/Nausithoe
The author there describes it is a Nausithoe.
<Ah yes>
I also found a reply from Ron Shimek on another forum:
He states, in reference to one of the images there that: "The four-lobed nature to the mouth is clearly evident, and that means that they are scyphozoan polyps"
<This is so>
I attached the original photo with the mouth circled and you will see the resemblance.
Just thought I would share my findings.
Thanks again and have a happy New Year!
<And to you! BobF>

Trying to identify -- 02/02/10
I have a 120 gal seahorse tank that has been established for over a year. I spotted two of these critters and would like to know what they are. I suspect either hydroids or jellyfish.
<It's hard to ID to any degree of accuracy from photos like this, but they look like jellyfish to me. Neato.>
I have removed them from the tank but I would like to know what I am dealing with.
<I wouldn't worry about them. I don't think they're hydroids. It looks like one of those things that, at worst, might have a population bloom, then disappear.>
Thank you, Sue
Sara M.>

Blue Jellyfish, ID, sys. 1/14/10
Hello I would like to first start off by saying I am a newfound lover of the marine aquarium hobby. I love it and have proceeded rather quickly at it as well...
<Welcome to our wonderful, seemingly all-encompassing avocation>
I have had several fishes die unfortunately due to a very fast start and learned my lesson. I am the owner of 3 tanks and have put in a fourth tank containing blue jellyfish. My jellyfish are using matured water from my another stable system, ammonia and nitrites at 0. They are running right now a cascade filter. 25 gallon tank with a 50 gallon cascade. I want to know several things, right now I cant get my camera to work but would like to send you pictures for ID as to know if they sting/swim or what not.
<And I will in turn send them on to friend Jim Stime of Jelliquarium for his help>
Next I need to know what kind of filtration needs they might have, further than the cascade that is. I can get several items as I have a pretty good supplier, but I do live in Costa Rica,
<Ahh! I have visited there a few times... San Jose, the Guanacaste area, even out to Limon. A great, progressive country in my estimation>
so availability and pricing are not the best. Also my jellyfish which I have had for a day seem to float at the top of the tank, right at the water level. I want to know why they stay at the top, they seem to be able to swim when they want to, they just choose to stay at the top. Not stuck in a corner because they move when they want to, just there. Is it lack of circulation, what can I use to correct this?
<Am going to send this letter on to JimS and have him respond. He knows MUCH more than I re these jellies practical husbandry>
Please let me know as I have several species here that I really like and I have had a hand pick selection including a wartskin angler that I need ID on (black with orange dots and rock colored spotting), I think commerson frogfish or maybe fancy frogfish, clown trigger,
<!? A bruiser.>
Humu Humu and a few others. Please help me with these jellyfish quickly so they can survive, I can get them Artemia to start, I have some actually. Then if you can help me with the rest I would like that as well but the others are doing fine now, its the jellies I'm worried about.
Thanks for your time.
<Jim, please respond directly and back to me. Bob Fenner>
Re: Blue Jellyfish, hlth. 1/14/10

What is a bruiser?
<The Clown Trigger!>
The black frogfish I asked you about? Anyways I'm really worried about the jellies, 2 are now at the bottom of the tank and 2 are at the top of the tank just floating, I dont think I see them moving, I might be wrong. They look slimy. like they are releasing some slime I mean... can you please help me so I can see if I can get them to be ok?
<How? Sans pix or data? Please read here: http://wetwebmedia.com/jellyfishfaqs.htm
and the linked files above>
Also do you have time to just look at the pictures of my fish and help me identify them?
<... perhaps>
I would really appreciate that. Oh, one more thing, how do you feel about yellow frilly scorpion fish?
<See WWM re>
worth $500 (and keep in mind that fish are expensive here, $200 for my clown triggerfish, and that was wholesale, $300 at the aquariums). What else can you tell me so I dont get myself stuck in the predicament I am in right now with the jellyfish. I dont want these animals to die, first and foremost I love sea creatures and dont want to kill them, second of all I spent a hundred bucks a pop for these jellies. help please....
ps.. I appreciate you looking out for assistance so you can help me better. Thank you and your friend.
<? Keep reading. BobF>
Re: Blue Jellyfish 1/16/10

Hello Xavierhe and Bob
>> containing blue jellyfish. <<
Most likely Catostylus mosaicus or the Blue Blubber
>> They are running right now a cascade filter. 25 gallon tank with a 50 gallon cascade. <<
What is a cascade filter?
>> if they sting/swim or what not. <<
In my experience I have NOT felt any sting, but I am sure they have some ability. Best to use gloves when handling any jellyfish
>> Next I need to know what kind of filtration needs they might have, further than the cascade that is. <<
Simple standard biological filtration, similar to a regular aquarium. I see a competitor of mine is using a simple bowl/ sphere with an undergravel filter.
>> I can get several items as I have a pretty good supplier, but I do live in Costa Rica, <<
These are OK to start with but I do not know of anyone who has had long term success with these. Generally if you can keep them for six months you will have done well. It is believed that they are photosynthetic and their mouths receive their food via 'radial canals' within each of those 'lobed' tentacles. This I believe means its very small food items, possibly copepods. I have tried several times to keep these jellies myself, all without success.
>> Also my jellyfish which I have had for a day seem to float at the top of the tank, right at the water level. <<
Assuming you just received the jellies its possible they have not acclimated to your salinity, hence they are buoyant.
Personally I am avoiding the tropical species due to their difficulty and working with the temperate Moon and Sea Nettle species.
Jim Stime, jr
Aquarium Design - Installation and Maintenance
MyFishTank.com - Acrylic Aquariums and Quality Aquarium Furniture
Midwater Systems - JELLIQUARIUM Jellyfish Display Systems
LA Fishguys - Aquarium Reality Television
Thanks much Jim. Hey, are you thinking of attending Interzoo this year? Can you maybe even slide in a week ahead of the May event to do a bit of diving in the Red Sea?
Re: Blue Jellyfish
Hi Bob, going to one of those shows would be awesome, especially going to the Red Sea... but I really cant afford to take time off work ( I backed out of that free trip to Kona this month and I am doing out-of-town jobs to fill in for the locals I've lost ) and I don't scuba, yet... but I heard from a service customer who went there and snorkeled and saw lots of stuff.
Jim Stime, jr
<Ah my friend. Remember years ago my urging you to take off at least once a quarter... I do hope we both live long enough to get out MUCH more often. Cheers, BobF>

Hydrozoan medusae: mystery solved? -- 10/31/09
Hello Dear crew,
I just wanted to share a bit of a mystery that kept me going crazy for many months.
<Oh! Please do>
There were two observations that I could not resolve with regard to identity. First, I kept seeing these little jelly fish-like creatures that occasionally appeared in my reef aquarium, and that mysteriously disappeared after a while. Second, there were these other creatures that looked sort of like little worm dusters, but clearly there were not dusters as they did not retract their crown when disturbed. After staring and poking into my aquarium for many months, and searching to no avail, I think I have it! The jelly fish are the
medusa stage of a Hydrozoan, and the "feather dusters" are the mature stage of the Hydrozoan (please see attached pic)!
<Nice work>
Please correct me if I am wrong.
<You are not wrong>
I am delighted that I seem to have finally made an ID, but of course not that happy that I have
hydrozoans all over my rocks. Is there anything that eats them?
<Mmmm, not specifically, no>
I do not want them to sting my corals!
<Best to keep filtering them out... eventually their source will be exhausted>
In any case, I just wanted to share the pictures as I could not easily find the info in the web, and it took quite a bit to reach the above conclusion. I hope this can be of help to others, having mystery jelly fish roaming their reefs.
<Thank you for sharing! Bob Fenner>

Found about 100 of these pulsating mushroom like things in my aquarium 9/2/09
No one locally has any idea what these are. They are about 1/8 inch long and swim exactly like a jelly fish. I collected about 100 in a breeding trap. Saw a Banggai gulp one in and immediately spit it out.
Any ideas?
<Are "jellies" of some sort... Scyphozoans, Hydrozoans, Ctenophores... I'd be netting them out and tossing or putting in their own system. Too likely to sting your other life, possibly toxify the system. Read here:
and the linked files above. Bob Fenner>

re: Found about 100 of these pulsating mushroom like things in my aquarium 9/2/09
Thanks for quick reply.
<Welcome Jack>
Tank has been set up over 2 years so the appearance of jellyfish now is surprising. There was one picture in the link you gave me that was close. I have been told that some coral reproduce with a medusa stage
<?! What the? No. These are strobilized...>
but have not found which species. I will pursue further from the links therein.
<Real good. BobF>

Need help in identifying this organism 8/16/09
WWM Crew,
I am dealing with a newly established (1.5 months) reef aquarium containing 75 lbs of live Fiji rock, two Astraea snails and two blue legged hermits.
While doing a daily scan looking for new aquatic life, I noticed an organism (see photo) attached to the front glass of the display tank. I thought it might be some type of jelly fish
<Yes... a Hydroid... Medusoid... versus a Scyphozoan... Cnidarian>
but was unsuccessful in making that determination. Could you please help me identify this organism and is it/will it be harmful to my aquarium in the future?
<Can be... if too numerous or there is small life you'd like to keep in the same system... e.g. very young/bred fishes>
The water quality is as follows:
pH 8.2
Ammonia 0
Nitrite 0
Nitrate < 5ppm
KH 196ppm
Calcium 360ppm
Phosphate < .5ppm
Specific gravity 1.023
Temperature 80 F
If I can provide any further information please let me know Thank You
<Not likely a worry... can be re-occurring... from strobilization off of material on rock... but not trouble unless too numerous. Bob Fenner>

Looks Like An Octopus: Likely Hydromedusae - Cladonema spp. 6/7/09
<Hello Brad, Lynn here today.>
I have little creatures on my tank walls that look like tiny octopi.
They have eight legs and just sit there for the most part. If they do break away from the wall (on their own, not with my assistance) they don't move in the water column, they just freefall until they collide with something. They then attach to that. Can you help me identify these animals?
<I'd need a photograph to confirm, but your drawings certainly help! I'm guessing that what you have are Hydromedusae, likely a species of Cladonema. For more information, please see WWM, starting at the FAQ titled 'Please Help Me ID a Jellyfish-Like Creature: Hydromedusae - Cladonema spp. 3/11/09' at this link: http://www.wetwebmedia.com/jellyidfaqs.htm >
Thank you for your time, Brad
<You're very welcome. Take care, LynnZ>

Looks Like an Octopus: Likely Hydromedusae - Cladonema spp. 6/7/09
<Hello Brad, Lynn here today.>
I apologize; this is my second e-mail to you.
<No worries>
I realized that I wanted to include a picture. I hope this helps.
<Yes, indeed, thank you!>
I have little creatures on my tank walls that look like tiny octopi. They have eight legs and just sit there for the most part. If they do break away from the wall (on their own, not with my assistance) they don't move in the water column, they just freefall until they collide with something. They then attach to that. Can you help me identify these animals?
<I'd need a photograph to confirm, but your drawings certainly help! I'm guessing that what you have are Hydromedusae, likely a species of Cladonema. For more information, please see WWM, starting at the FAQ titled 'Please Help Me ID a Jellyfish-Like Creature: Hydromedusae - Cladonema spp. 3/11/09' at this link: http://www.wetwebmedia.com/jellyidfaqs.htm >
Thank you for your time, Brad
<You're very welcome. Take care, LynnZ>

Hydromedusae or Staurocladia Maybe 5/14/09
I just want to say you guys are incredible and have given me a lot of value information in the past and was hoping you could help.
<Will try>
A friend recently found a small Jellyfish in his reef aquarium and asked me if I could Identify it. Off the top of my head I could not tell the exact species. It appears to be a type of hydroid but I am not exactly sure.
<There are several species... some quite similar in gross appearance>
I spent a few hours searching and could not get any specifics. It is very similar to the critter described in the first post I found with you guys.
FAQs on the Ctenophorans, Scyphozoans and Hydrozoans: Jellyfish Identification
Except that it is quite a bit larger, the bell measures 5mm wide and 6mm tall, roughly, and when the appendages are extended it exceeds half an inch. Also the structure within the bell when viewed from the top or bottom is in the shape of a star.
<Mmm, indicative more of true jellies (Scyphozoans), but still....>
The structure appears to be composed of many spheres that stack 3 high.
It also is fairly red in color but does change when bothered.
Also in the center on the bottom is a white dot. The appendages are clear with white dots that I assume are the nematocysts. It has 8 appendages fyi.
Also my friend informed me that prior to his discovery of these little jellies he did notice that his arms became itchy whenever he worked in the tank (now he does not play in the tank).
<I'd be wearing gloves>
Is this a slightly different species or am I just crazy?
<Not crazy>
The picture attached does this jelly no justice.
Thanks for all your help!
<Can you send along a better pic? I'll send it along to ask others in the know. Bob Fenner>

Please Help Me ID a Jellyfish-Like Creature: Hydromedusae - Cladonema spp. 3/11/09 Dear Crew, <Hi Mike, Lynn here this evening.> I am a long time freshwater aquarist, who has recently delved into the saltwater world. <Neat!> I have scoured the internet trying to identify the jellyfish-like creatures that I have in my tank of clowns. <Okay> They appear to act like a jellyfish; <For good reason!> ...there are hundreds of them in my tank. They primary sit on the bottom of the tank looking clear and bell shaped with a beige colored column in the center, they have 9 appendages with tiny hair like extension. At other times they attach themselves to the glass. When on the glass you can clearly see the appendages and the hair like extensions. The largest is 1/8 inch in diameter to the end of the appendages, not counting the hair like extensions. If a baby brine shrimp drifts into the extensions it is quickly caught and dragged to the center of the appendages and consumed. They propel themselves by compressing the bottom part of the bell to expel water. They can move quite quickly for a short distance. They then drift to the bottom or side of the tank, like a parachute. <Terrific observations> I am attaching photos and a short video to assist in the ID of these creatures. <Excellent, thank you!> What are they? <They're hydromedusae/jellyfish in the genus Cladonema. Size is usually ~2-3mm. As you mentioned, they spend most of their time either swimming about or clinging to the substrate, etc. According to Dr. Shimek, they likely feed on 'small copepods and particulate material in the water'. For more information, please see the following links: http://jellieszone.com/cladonema.htm http://melevsreef.com/id/jelly.html > They don't appear to have harmed anything in my tank. <Good!> Will they sting like jellyfish <It's possible, yes. They have nematocysts/stinging cells so they are capable.> ...and is there any need to worry about harm coming to me or my fish? <Unfortunately, I couldn't find anything conclusive as to how 'safe' these are in a system with fish, but I haven't heard/read of any horror stories either. Personally, I wouldn't want to see them in a tank of clownfish (or any other) fry, or baby seahorses, but other than that, I wouldn't be too concerned. The general consensus seems to be that they're 'mostly' safe. As to whether you could get stung, I imagine you could, but I just don't know how much effect it would have. It might be negligible unless you picked up a handful of the little creatures, or were allergic/sensitive to them. Again, I just don't know. I would play it safe and avoid contact. If you are at all concerned, or see any signs of livestock stress, I'd remove them/reduce their numbers via a siphon or turkey baster. More than likely, though, these jellies will stick around for a little while then disappear.> Thanks for your help. Mike
<You're very welcome. Take care, Lynn>

Re: Please Help Me ID a Jellyfish-Like Creature: Hydromedusae - Cladonema spp. 3/12/09 Lynn, <Hi Mike> Thanks, I also checked out the website you referenced. Great info. <Excellent> Mike <Take care, Lynn>

Micro-spider 'pods? 2/22/09
I just set up a 90 gal reef system with about 120 pounds of live rock.
I'm seeing the usual suspects as far as 'pods go, but I saw a new one today:
about the same size as other tiny pods, but have 8-10 legs in a starfish type pattern. They are about 1mm across, including legs, less than .5 mm without legs. Baby stars?
A type of 'pod I can learn about?
<Photo/s please. Bob Fenner>

Re: micro-spider 'pods? 2/22/09
Thanks. My camera won't focus in closely enough. Looked through everything I could find on your site (plus others), so I'll probably just have to live
with the mystery. Appreciate the time.
<Welcome Dan... do keep your eyes peeled for someone with a "close up" feature on their small digital camera... A common feature now a week!

Re: micro-spider 'pods? 2/22/09
Best I could do (attached). Thanks for the idea...I'll keep my eyes peeled.
<Ooohhh, this looks a lot like Staurocladia. Please scan here:
Bob Fenner>

Re: micro-spider 'pods? 2/22/09
BINGO! Thanks, and have a good one.
<Ahh! You as well Dan. BobF>

Help ID'ing this critter! 1/19/09 Hi Crew, I have seen about four of these guys in my tank in the last two months. It looks like a very tiny jellyfish 1-2 mm in width, bell shaped and when in the water column it is free swimming with a pulsing kind of motion. <Are medusoids... of some sort> I have attached some pictures of one I scooped from the tank, it is in a clear plastic bowl lying on a towel, (that is the hairy material in the background). I also managed to capture a video clip of it swimming in the water column here http://s464.photobucket.com/albums/rr2/KKamysek/?action=view&current=MVI_0222.flv. <Neat!> While it was free swimming, my Banggai Cardinal chomped on it and quickly spit it out, making me think he got stung (or maybe he just didn't like it). The closest reference I can find is it may be Cassiopeia Andromeda in reproduction mode? <Mmm... doubtful... do you have these in your system as adults?> Is it detrimental to my reef? <Mmm, they could be... as you postulate above re apparent palatability...> Should I be getting rid of these guys when I see them? <If too numerous and/or you see your other livestock suffering from their presence... Likely are strobilizing from some hard surface (e.g. live rock)... could be Scyphozoans, Hydrozoans, even Ctenophores... Please see WWM re. Bob Fenner> Thank you,

Another New Critter - 7/2/08 Crew, <Jared> I found another critter today that I have actually seen before, but have never been able to get a good photo of. I have a few of these in my tank, and they are either swimming or attached to the glass. <Ah, yes! Was out for dinner at a friends last night and they played some of the excellent "Blue Planet" series... part of which featured some great footage of strobilization...> They are about the size of a pea, disc/umbrella shaped, and "pump" their bodies while they swim AND when they are attached to the glass. I thought they were some kind of jelly, but I haven't been able to find a picture. The attached photo isn't the best, but I think you can get a good idea. Thanks again, Jared S. <Is indeed a jelly... There is but a small bit re their appearance, concern posted on WWM. Please do relate further observations you have re. Bob Fenner>

Re: Another New Critter... Jelly! 7/3/08 Bob, <Jared> Thanks for the info. I searched WWM today and found a post from Jim Stime regarding Moon jellies. The photos he posted of the juvenile Ephyra matched nearly perfectly to what I have in my tank. <Ahh!> I actually have some of the polyps on my rock, and I am guessing since I don't have the correct tank for jellies, the ones that I see swimming don't last long. I will try to take better pictures, but I think we may have solved this one. Thanks again Bob... Jared S. <Thank you for sharing. BobF>

Scyphozoa Question 6/16/08 Hi, <Greg> I have discovered that I have what appears to be several jellyfish (Scyphozoans) in an aquarium I use for experiments. <I saw a bunch of settled Ctenophores in shops this last wknd. in Phoenix. Okay, your turn> The system (less than 1 gallon) is unfiltered with no outside inputs except for a very small amount of air from an air stone. I had ordered some rotifers about a year ago and placed them in the system. <Ahh!> They did not last very long. I cleaned off some algae from the side of the system recently and noticed jellyfish that are about 2 mm maximum in size. I am assuming jellyfish eggs or planula came in the rotifers batch I received last year. <Likely so> Their locomotion is identical to larger jellies. They have a clear/translucent bell, some reddish/maroon color inside the bell and translucent tentacles or oral arms. <Neato> Have you ever heard of captive jellyfish outside of a large institutional (city/corporate) aquarium? <Oh yes... in fact, a friend, Jim Stime, makes/sells Jelliquariums... and I saw some very nice, much cheaper models a couple weeks back at the Interzoo show in Germany... it's a biz> Do you know of sources I could use to identify these guys? <Mmm... am referring you to Jim Stime here... you can also reach him via Jelliquarium (.com)> I cannot provide a picture easily. They are too small for my camera equipment. <Macro settings, large file size... cropping...> -- Thank you, Greg S. Hurley <Ahh! Had a fine H.S. Geometry instructor with your family name here in San Diego... years back! Cheers! Bob Fenner> Re: Scyphozoa Question 6/16/08 Hello Gregg and Bob, The jellyfish portion of the hobby is just now becoming possible. As such there is very little information available... but its increasing. I have kept, for only a short time, Ctenophores, but have not been involved with their reproductive cycle. Moon jellyfish are the most common and have the greatest amount of research and information available. These are the pale white discs with short fringe tentacles around the rim and the familiar four-leaf clover pattern within the bell. Most jellies have a polyp stage where the medusa strobilates or a-sexually buds off from the oral disc portion of the polyp. Once the juvenile has freed himself he is now called an Ephyra. It takes another 60+ days to raise these jellies to 2 or 3 inches. Here is a short video of my jellyfish production system >> http://www.lafishguys.com/midwater/JellyNursery001.htm << Based on your comment about " some reddish/maroon color inside the bell " I suspect what you are either seeing the food stuff brought up into the stomach of a Moon jelly species or you may possibly have a species of Sea Nettle, Chryasora species. These tend to have much longer tentacles... and ones that sting too. Aside from the Upside-down Jellyfish all other species typically require a tank that keeps the jellies suspended once they have bud-off from the polyp. Here is an article I wrote on the process >> http://www.jelliquarium.com/DocumentPage.aspx?id=1034 << There are only a few good books available on jellies. Most are written for 4th graders. Let me know if I can help you further. Jim Stime, Jr. 805-241-7140 Aquarium Design www.aquarium-design.com MyFishTank.com www.myfishtank.com Midwater Systems www.jelliquarium.com LA Fishguys www.lafishguys.com <Ahh! Thank you Jim. BobF>

Re: Scyphozoa Question 6/16/08 Hi Bob, >> I saw some very nice, much cheaper models a couple weeks back at the Interzoo show in Germany... << Can you tell me anything about these systems ? <I picked/saved up some lit to give you I picked up... just got to find it again!!! BobF> Jim Stime, Jr. Most impt.... they were very nice... and cheap... like about a fourth of yours in cost... Trouble if they're offered in your mkt. for shore. B.

Re: Scyphozoa Question 6/16/08 Bob and Jim, <Mr. H.> Thanks for the info. I think I might have to get into jellyfish. Sounds like a fun new challenge. <Are indeed> Thank you, Greg S. Hurley <Welcome Greg. BobF>

Need Help With An ID No One Knows In My Reef Forum 2/24/08 <Hi Jim, Mich here.> I bought snails from the LFS and on 1 of the shells was this aiptasia looking thing, that's what I assumed until it released itself and started swimming. It swims like a octopus flailing its tentacles I've posted on a reef forum and looked all over the Internet researching this thing but have come up with nothing. Any help would be appreciated. <Looks like a hydroid jellyfish to me. More here: http://www.ronshimek.com/Animal%20Groups%203%20Cnidarians.htm http://www.wetwebmedia.com/jellyidfaqs.htm > I do have it in a catch bucket but was wondering if it's safe to put it in my reef. <Likely wouldn't hurt. Populations tend to wax and wane. Is interesting to observer for sure.> Thank you for any help you can give me. <Hope this helps. Mich>

Id: Staurocladia oahuensis - 10/16/07 Hi, <Hi there, Ben> This tiny little fellow, about 50 thousandths of an inch across, is presently adhered to the front of my tank: http://www.flickr.com/photos/fyngyrz/1573547118/ <Nice photo!> He looks like a baby anemone of some kind to me. Any of you recognize the lil' fellow specifically? <Heeeeee, well, not that one specific individual, but I do recognize the specie: Staurocladia oahuensis. These are tiny crawling hydromedusae, also known as hydroid jellyfish, and are generally not a problem. They typically wax and wane in aquariums, sometimes appearing in great numbers, only to disappear a short time later. Please see these links for more information re: http://www.wetwebmedia.com/jellyidfaqs.htm http://www.ronshimek.com/Animal%20Groups%203%20Cnidarians.htm > --Ben
<You're very welcome! --Lynn>

Baby Mini Brittle Star? Nope, Hydroid Jellyfish! 8/19/07 I was wondering if this was a mini brittle star. <Nope, it's a teeny tiny crawling hydromedusae (Staurocladia oahuensis) and generally nothing to worry about. Please see these links for photos and more information: http://www.wetwebmedia.com/jellyidfaqs.htm http://www.ronshimek.com/Animal%20Groups%203%20Cnidarians.htm <Take care -Lynn>

ID question: ovoid pulsating 3 mm animal in fuge 5/30/07 Hello to all the crew! I would be very curious to know what this is. Very intriguing. It's about 3mm in diameter and moves in a pulsating way in the water column. It never settles on the substrate. It's a very slow flow fuge. The way I see it, it wouldn't last long in the display. For what I know it's been there for the last three days and never noticed something like that before. I didn't add anything in the last few months. <Are strobilizing from some hard media...> I am not worried, just very curious. Here are 4 pictures. There are SPS and LPS in my thank as well as sponges (hitchhikers). Could it be the larval stage of a coral. I guess not given the size (3mm is somewhat big). Thanks in advance!!! Dominique <Looks to be a Ctenophore to me... A Comb Jelly... Bob Fenner>

Re: ID question: ovoid pulsating 3 mm animal in fuge -- 5/30/07 Thanks a lot Mr. Fenner! Puts me on the right track, will be doing searches with this... Dominique <Really neat animals... and always reminds me of one of fave H.S. teaching jokes re the Radiata (group including the Cnidarians and Ctenophores)... "Hold old are most Comb Jellies?"... "Most are in their "teens"" (as in "Teen Oh Phore"). No groaning now. BobF>

Staurocladia oahuensis (hydroid jellyfish) 03/25/07 Hello Crew, <Hi.> I browse your site extensively and read just about everything on it. <Awesome.> I have tried searching through your site and have not found what I'm looking for to this particular creature. see attached). <Appear to be Staurocladia oahuensis (hydroid jellyfish). Generally speaking they are readily consumed by most life forms in marine aquaria....similar to the plight of other microcrustaceans/copepods. There populations seem to go and come with little consistency. I would not worry.> The pic was taken through a magnifying glass with the camera on the close up setting so unfortunately, it doesn't get better than this. <No worries, was able to I.D.> 125 gallon 6ft long 3" DSB Sump that is in process of becoming refugium <Good.> Porcupine puffer (2") <A baby! Will grow quickly...> Dogface puffer (5")Diamond goby Fire Shrimp assorted snails and hermits~50 <Careful with the goby and hermits both could wind up being puffer lunch.> lbs LR Mail ordered shaving brush plants LFS bought Chaeto in sump I have tried looking through pics of a copepods life cycle and it doesn't resemble this. Some of these creatures have 5 "arms" others appear to have 8. If anyone has an idea I'd love to hear it. Also I keep reading that there are web sites devoted to determining kinds of animals, after an exhaustive search through Google, I cannot find one that offers crisp pics of organisms through there life cycles. Any ideas on this also? <There are a multitude of sights dedicated to helping hobbyists with these types of issues, they are difficult to find though if yo don't know where to look. I would suggest asking the folks on our free chat forum: www.wetwebfotos.com/talk....there is much posted re: this issue.> <Adam J.>

What The?!...A Tiny Hydromedusae - 01/17/07 Tara here, <<Hello Tara...Eric here>> Ok I've searched and searched. <<ME TOO!...ummm...what are we looking for?>> Here on your site there have been two different answers to this question. <<Ah, a 50-50 chance of being right...better odds than most...>> But what are these? <<Staurocladia oahuensis (hydroid jellyfish)>> The disk itself is about the size of two male copepods. Look a little like tiny brittle stars. <<Indeed they do...but they aren't...at least not in my opinion>> They're all over the glass in my zooplankton 'fuge. <<Nothing to worry about/won't cause any problems...and will likely disappear as quickly as they appeared. Study/enjoy them while they are around. Eric Russell>> Tara

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>

Medusae ID - 07/28/06 Thank you for getting back to me about the use of these light strips. By the way my name is Michelle. I forgot to add my name in my last email due to the stressful situation I got into. <<Quite welcome Michelle, but I'm not sure who your thanks should go to since you didn't include the prior exchange>> I recently purchased about 4-pounds of live rock from LFS on Sunday. I have it in my main tank curing with my protein skimmer running 24/7 and it's going well for the curing. <<Okay>> I have been up late every night looking at the amazing life that's on it and have been using your website to help identify a lot the creatures. <<Hee! What an amazing hobby, eh!>> I'm currently having an issue with trying to identify a new creature I found floating around my tank. It's shaped like a bell, a dark creamy, clear color and it pulsates. It has a small whitish spot on the top and has about four smaller whitish spots on the very bottom. It's about the size of a pin head. <<Wow, you've been doing some "close" observation indeed!>> I'm using my daughter's magnifying glass from her sea-monkey kit. <<Excellent!>> It's really too small to photograph with my camera. I was wondering is there a link for photo id's on jelly fish so I can compare it to the pictures. It really is a cool critter. <<Mmm...is likely the medusae stage of a coelenterate, the "whitish spots" you see are probably ocelli...a light-sensing organ. This may or may not be a jellyfish (though your initial description does sound as though) and I think a positive ID is going to be tough, but you might just try a Google search on the keywords 'Jellyfish Medusae' or even just 'Medusae' to see what you can find. It is not unheard of for Cassiopeia jellyfish to make it in to aquarist's tanks via live rock/coral additions, but I don't know that it will be possible to identify as such at this small stage. You might also try a search on the 'Moon Jellyfish'>> After finding this thing now my husband is really interested saltwater tanks. <<Cool!>> I was wondering is there a link that I can use to photo ID this critter. <<Not that I know of just off-hand...do try the keyword search>> Thank you again for your help. Michelle <<Happy to assist...good luck with your search. Eric Russell>>

Jellyfish Surprise! - 5/11/06 Hello, <<Howdy!>> I noticed something today in my aquarium, it's a VERY small jellyfish looking thing. <<Neat!>> It's smaller than a pencil eraser and swims in the current of my aquarium. None of the fish bother it either. Is this normal? <<Mmm, not "normal" in the sense that it happens all the time...but not unheard of>> Will it bother anything? <<Likely not, nor will it probably survive for long...enjoy it while it is around>> Brian
<<Regards, EricR>>

Hydroid Jellyfish - 05/02/06 Dear Mr. Fenner, <<Eric Russell here today!>> I have an infestation of what appear to be tiny hydroids lining the walls of both my QT and my main tank. <<Mmm yes, some of these just popped up in a member's tank in my local club...is a tiny crawling hydromedusae...Staurocladia oahuensis...nothing to be concerned with>> I recently imported a rock of Ricordea, and some Banggai cardinals. <<May have come with the rock>> The fish I quarantined, the rock I didn't. I assume the rock had the Hydroids on it, but I have many more hydroids in my QT. <<Easily transferred in water/on equipment>> However, I do use main tank water as replacement for my QT... so who knows where these little buggers came from? <<Indeed...and under optimal conditions they will multiply rapidly through asexual budding or fission...just one can become hundreds...only to disappear just as quickly>> Question: I hear these little guys eventually "just go away"... is that your experience? <<Yes>> Question: Do I need to tear down my QT? <<I wouldn't for this, no>> I'm getting it set up for a pair of clowns. Can hydroids injure fish? <<I don't believe these to be a danger>> Russell in KY
<<Quite welcome, EricR in SC>>

Comb Jellyfish 12/13/05 Hi Bob, <Jimbo> Quick note. See attached picture <Nice> The jellyfish product line keeps growing. I just received a shipment of Comb Jellies out of Key West last week. <How old are most comb jellies? Most are in their teens (Ctenophora)> Under the MH their fine rows of hairs reflect the light in a UFO landing strip type light show. Awesome ! Jim Stime, jr. Resplendent Group Aquarium Design www.aquarium-design.com MyFishTank.com www.myfishtank.com Midwater Systems www.jelliquarium.com Centropyge.Net www.centropyge.net MACNA X www.masla.com/macnax.html
<Beauty. Bob Fenner sans list>

Baby jellies... or some other creature? 1/4/06 Hi crew, <Chris> Sheesh. I had to get creative to photograph these critters. I snagged one with an eyedropper, placed it in a water drop on a slide, and popped it into my $20 National Geographic 'scope. After removing the eyepiece shield, I was able to snap a few photos of reasonable enough quality for ID purposes... I hope. <Neat> These pics are slightly out of focus, but the best I could get and still get the whole thing. ('scope/lens/user? limitations) I've seen some dozens of these, over the past few days, in my 55G saltwater tank. I'm seeing fewer lately, due to losses in my power heads and/or filtration, I suppose. (Or predation?) <A combo. no doubt> I didn't notice them today, until swishing around my LR with a turkey baster... blowing off some food that had 'settled'. (Perhaps these had 'settled' too... and I stirred them up?) <Likely so> Anyhow, they look for all the world like mini-jellyfish of some sort, though I couldn't imagine from whence they came. My only recent addition is a 6" ball of Caulerpa Racemosa from my QT. (Note that this QT also contains assorted amphipods, worms, and other tiny marine life that has accumulated over time) The Caulerpa had been in the QT for three weeks. <Mmm, are some sort of medusoid life> Most are about the size of this period. (Some are a bit larger) The photos show the rest of my observation. At "rest", they're full of water, their "valve" is closed, and you can see a few small protrusions between the two dark spots at the valve end. To move, they appear to expel water through the 'valve', and they contract axially, while extending longitudinally. (Moving away from the 'valve' end, of course) <Yes> Enough of my rambling, I suppose. Please edit and ditch any irrelevant babbling as you see fit. I won't mind. Do these look like anything you've seen before? <Mmm, yes... juvenile "jellies" of some sort (Scyphozoans, Hydrozoans) or ctenophorans...> Feel free to whack me in the head with a book of your choice, if these are something very common that I should've found on a simple web search. (I looked, but perhaps not hard enough) Tell me if you need more info, tank specs/inhabitants, etc... Thanks in advance, Chris <I wouldn't be overly concerned re these being in your system... likely "strobilized" from the new algae... or some other substrate. Will pass with time. Bob Fenner>

Tiny Jellyfish 2/23/06 Hi Guys! <Lesley> Hope you are keeping well - it's been a while since I last contacted you so I hope you are all ok. <I am, thanks> Two days ago, in the smaller of our two marine tanks, I noticed three, tiny white jellyfish-type critters - literally, the mushroom shape, but no tentacles - quite "stiff" in structure and jerky in movement as opposed to the more fluid, typical jellyfish. They were about 2mm - 3mm in diameter and were "swimming" around the tank being ignored by the fishy occupants. I think they're cute! Anyway, today, I counted 7 of these tiny critters, varying in size from about 1mm to 3mm across the top of the "mushroom". I still think they're cute but have no idea what they actually are or where they came from as we haven't added anything new to the tank for several months. I wondered if you could help. Sorry the description is so vague. Also, they are too small to photograph clearly. Any light you can shed on this would be most appreciated! Many thanks! Lesley Saxton <There are quite a few Scyphozoan and Hydrozoan medusoid animals that can strobilize from hard surfaces introduced in our marine systems... Use these terms in your search tools... and you'll see. Bob Fenner> Tiny Little Jellyfish Things ??? Bob, I have recently discovered these tiny creatures in my marine tank, evidently they arrived on the new piece live rock I inserted a week ago, I have not been able to find out on the web what they are or identify them in any of the books I own. I am hoping that you have a clue as to what these new species are. The creatures have a round flat translucent top then a cylinder and tentacles and are about 1 to 2 millimeters in size. They look like and swim like little jellyfish constantly trying to reach the waters surface. The fish in the tank seem to take no interest in them but do swim around them with a wider berth then other things in the tank. Thanks, Jason <almost certainly harmless or even beneficial. Many pelagic marine planulae and medusae (as with jellies) look very similar at young stages. If you have any Atlantic live rock or recently put in snails or hermits from the Atlantic, then you may have the young medusae of the non-stinging "Upside-down" jellyfish (Cassiopeia). A photosynthetic and hardy creature if kept from pumps or strong current (great fun and somewhat easy to keep in a fishless seagrass refugium). At any rate... enjoy until it gets larger when it can be better identified. With kind regards, Anthony Calfo>

Oh No! Yep I said jellyfish I have come across these jellyfish in aquarium stores many times. They are small and colorful, usually a light blue to a white color. They aren't very expensive either. I wanted to ask you a simple question about them: Should I even try to keep one? Or are they just a "gooey" form of the Moorish idol. I tried to do some research on the internet and didn't come up with much on husbandry. I did hit a lot of aquarium sites and learned vaguely about the animal. Anyway I don't know the common or scientific name of these jellyfish. I have included some pictures, could you please identify them and tell me more about them. I fully understand how the tank should be set up...I need to learn about their eating habits though..... Thanks for all the help, Dinesh <Looks like a mixed (dyed) group of Cassiopeia andromeda jellies. Please see here re: http://animaldiversity.ummz.umich.edu/accounts/cassiopeia/c._andromeda$narrative.html#food_habits and http://www.liveaquaria.com/product/prod_Display.cfm?siteid=23&pCatId=543 Not easily kept. Bob Fenner>

Question about jellyfish Hello, <Hi Bill and Donna!> I'm a customer of Marine Warehouse in Tampa, Florida. During a visit for a few items this evening we took along a sample of water with items that look like tiny jellyfish that have begun growing in out 10 gallon salt. The folks there took a look and said "Those are jellyfish and we've NEVER heard of them reproducing in a 10 gallon. You should email Anthony Calfo or Bob Fenner at WetWebMedia and let them know what's going on". These animals start out growing on the rocks, then sort of "detach" themselves and, well, swim around the tank like jellyfish--the size of a bb or so. <Wow! This is one of my favorite things about this hobby! There are several possibilities here. Some hydroids have a "medusa" stage that is planktonic and resemble tiny jellyfish. Some of these could have reproduced in the tank or been accidentally imported. Also, some hydroid or jellyfish medusae could have been incidentally bagged in the water with another animal. Is this worth our sending you an image? <Probably not. It is unlikely that any of us have the references to make a positive ID, even if you could get a good enough pic. It is interesting that you got sent to just the right place... Anthony had this same experience in his greenhouse, and traced the introduction back to a shipment of Astrea snails from Florida. He grew the medusae out into full adult Cassiopeia (upside down) Jellyfish! The pump free, well lit, fine sand bottom environment of the green house, combined with the fact that Cassiopeia are photosynthetic bottom dwellers and probably the only jellyfish that is even remotely suitable for the home aquarium all contributed to this enigmatic success.> All the best, Bill and Donna Tampa <Thanks for sharing this great experience. I'm sorry to say that most jelly fish will not survive under any circumstances, and even if they are Cassiopeia, duplicating Anthony's greenhouse conditions would be difficult. If they are hydroids, you will see them start to settle out onto tank surfaces. Best regards! Adam>

Re: Question about jellyfish 1/21/04 Hello, Adam; Thanks so much for your kindness in walking me through this. First of all, let me clarify my mandarin status: We have a male and female; however, they have not, to my knowledge, spawned. I doubt we would be able to raise them if they did. Our success is keeping two in a 10 gallon aquarium. Not too common, I think. <Indeed it is quite a feat to keep a pair of mandarins in a 10 gallon, I thought that was a typo!> The jellyfish thing is perplexing. I know some folks would kill to have jellyfish reproduce as they are in our tank, but they're taking over! It seems as if they are not just hatching and milling about but are in a life-cycle. They would be cute if we had one or two tiny ones puffing about but they're hatching every day. I don't know if they'll live, die out or what. I'm afraid they're not going to just "go away". I've talked to a couple of professors who specialize in jellyfish and they don't have a clue as to why it's happened and what to do about it. Could sure use your help! Bill <It sounds like these may be hydroid medusae. Some hydroids have medusae as part of their life cycle, some can go back and forth between sessile and medusae. My only suggestion is to mechanically filter them from the water. Regardless of where they are coming from, this should quickly eliminate them. HTH! Adam>

- Cassiopeia spp? - Hello you helpful people there! This link www.internationalbirds.com/mysquishy.wmv goes to footage of a tiny (<5mm dia) hitchhiker that my husband retrieved from one of our established tanks today. <Neat!> It looks like Cassiopeia to me. I know the pix are not wonderful but the thing is so tiny and we don't have a macro lens. Anyway, it swims like Cassiopeia. <Many jellyfish swim this way.> And it lies upside down on the bottom and wafts BBs into its central organs (I assume tentacles). <Could be an artifact of prevailing circulation or lack of it.> Can you confirm or deny this ID? <Not really... the organism is so very small so it's hard to tell. Quite possible you are correct.> BTW, any idea on how it might have arrived? <Possibly on live rock.> We haven't added anything recently except 2 new seahorses a couple of weeks ago. <Well... this seems small enough that it could have been planktonic when it first arrived.> Sure appreciate your help, Deborah <Cheers, J -- >

Jumpin' Jellies? 2/6/04 Hi Crew, <hiya> I just found something unexpected in my aquarium! This little thing is slightly smaller than a pea, transparent, dome-shaped with what appears to be very tiny tentacle hanging down from its outer edges and moves by pulsing the dome. Basically this thing looks just like a very tiny jellyfish. Is it possible that I could have a jellyfish in my tank??? <yes... easily. I have had this occur in my aquariums and heard it from others. They are always medusa from Cassiopeia upside down jellies. They come in with water (or on shells) with turbo snails, blue leg hermits or Atlantic live rock for example> The only thing I can imagine this coming in on is live rock but I haven't added any rock for at least four months. <still possible... long slow growth. Also the snail/crab factor if you added any> I though jellyfish needed very cold water also (my tank is at 77 degrees F). <many tropical species mate> If this is a jellyfish, should I be concerned at all; I mean is there a change it will grow-up and sting my fish? <nope... if so, these are non-stinging and photosynthetic. In fact, you need to remove them to a safe refugium or separate tank else they will die in the pumps or overflows in time> I assume my fish would eat it first (several decent-sized tangs) but I thought I should check. Hopefully you can shed some light on this mystery animal! <please do look up the genus I mentioned on the net. Bob and I will be covering these fascinating cnidarians by the way in our 3rd volume to the NMA series (due 2005 likely... vol. 2 this year). Anthony>

Jellyfish - 2/9/04 Hello there, I first want to commend you on your wonderful and informative site, I've learned more here in the past week, I've discovered, than I have all month searching on the web. <Happy you have found us and thanks for the kind words> Realizing that marine aquariums is a form of art for the modern man, I've decided to take my artwork into the 21st century and do something a little different. <very cool> At my LFS I came across a little tank with about 5 white jelly fish, they didn't look like the upside down ones that I have seen, <Cassiopeia, the "Upside-down Jellyfish". Sometimes sold as an aquarium species. These are shallow water lagoon and mangrove swamp animals that use both photosynthesis (via symbiotic algae) and many small mouths scattered on their "tentacles" (eight oral-arms) to suck-in zooplankton for food. Favored foods of Ocean Sunfishes and marine turtles.> they looked like traditional jellyfish with medusas "I think is the correct term" about the size of a racquet ball. <medusae refer to the polyp stage of larval jellyfish> My friends said that there are stores in Orange County where I can obtain different colored jellyfish. <Not sure what you mean here? You mean multi-colored jellyfish or jellyfish of different types and colors?> So I want to do a tank with red and blue jellyfish i.e.. the bloods and crips. <Ummmmm.....OK> They looked so magical just floating around in their tank that I think it would be a great vibrant color show to watch. <Are these natural colors or dyed? Can you get some pictures of said jellyfish and send them along to me for identification?> I can not find any specifics on how to set up such a tank or what species those jelly fish were, unfortunately I can only understand every five words from the store owner because of his thick accent. <Where do I begin. Holy smokes. Well.....maybe start here: http://www.masla.com/invert/jellyfishpets.html and here: http://www.wetwebmedia.com/jellyfishfaqs.htm and yet another article from a friend of mine: http://www.reefs.org/library/talklog/r_toonen_051798.html. Hope this helps ~Paul> Any help or knowledge would be greatly appreciated.

Unknown creature Hi. I have three pics of something that I cannot identify. Firstly, I am sorry about the quality of the pics. Here are links to them. Caught one in a test kit tube and brought it into my computer room. They do swim, but are mostly stationary on the sides of the glass. Not copepods or amphipods. They also "pulse" every so often. The pics don't show it well, but around the small white part of it, there is what looks like a bubble around it. Think of a jellyfish. Thanks, Todd <Mmm, some sort of polypoid cnidarian... a scyphozoan or Hydrozoan of some species, which doesn't narrow the search down much... I would definitely go with the common name "Jellyfish". These likely will keep reappearing in small numbers, and perish by starvation or be sucked up into your skimmer, other filtration. Bob Fenner>

Finicky feeding fish and unidentified polyps Hi, We are working with a 20G tank, lots of live rock & live sand. Filtration: Fluval 2+, protein skimmer, & sponge filter. Inhabitants: 2 seahorses (about 8 months), 1 mandarin (about 6 months), 1 sand sifting star (about a month), 2 hermit crabs (forever =), & 3 feather dusters (long time). Good water quality. 1 50/50 or daylight fluorescent tube (can't remember) running about 12 hours/day. There are lots of nice things growing on the live rock: some coral, some macro-algae, some teeny feather dusters. There also seems to be some bristle worms, bad news I think. << Bristle worms are great. But I would definitely remove the sand sifting star. They can deplete and devour micro fauna, and you happen to have chosen fish that need that fauna. >> Lately some little clear things have grown all over the live rock & even on the hermit crabs :-O they are about 1/4", basically clear. They have short stems & waving arms. We thought they might be feather dusters but they have no tube & stay out. << Hmmm, not sure. Probably still a worm. >> We then thought anemone, but think the stem seems too long. We brought a small piece of coral to the LFS with some sticking on it. They brought out a microscope & looked very carefully at one of them that had detached & was at the bottom of the bag. It was pulsing, they came up with the verdict of Cassiopeidae (upside down jellyfish) polyps (baby jellies they think). We looked over your *fab* site to see how to get rid of them, but they look very much like hydroids in some pictures. << Not sure I would get rid of them. But if you do want to, I'd be willing to bet many other common fish would eat them. >> Will you please advise on whether these may be harmful to our occupants and how to get rid of them if so? << I'll say not harmful, so don't worry. The main concern is really feeding those finicky fish. >> Thanks for all the help and for a great site!!! Michael & Patty << Blundell >>

Jellyfish I was looking into my tank at my new Blue Linckia Starfish (thank you for the advice by the way, he's doing great!) and I saw a tiny (about 1mm) jellyfish swimming around my clownfish, it must have come in with my live rock. I could tell that it is a jellyfish because of the way it was moving; it's really quite unmistakable. What should I do with it? Will it harm my fish? Do you have any idea how large it will get? If I decide to get rid of it what can I do with it, I don't want to kill it. Thanks, Elizabeth <Liz, jellyfish are not reef safe and most are toxic to people. Take it back to the store and see if they want it. I don't believe you would want to set up a small tank for it and furnish it the necessary plankton it needs to survive at this stage. James (Salty Dog)><<Uhh, one millimeter... just ignore it... they too shall pass. RMF>>

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