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. <Neat!> 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.
<Neat!>
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.
<Mmmm>
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!
Robb
<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?
<Maybe>
A type of 'pod I can learn about?
<Certainly>
Thanks,
Dan
<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! BobF> 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: http://wetwebmedia.com/jellyidfaqs.htm 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, Karl

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>>

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>

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>>