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FAQs on the Hydrozoan Identification 5

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

Related FAQs: Hydrozoan ID 1, Hydrozoan ID 2, Hydrozoan ID 3, Hydrozoan ID 4, Hydrozoan ID 6, Hydrozoan ID 7, Hydrozoan ID 8, & Hydrozoans 1, Hydrozoans 2, Hydrozoan Behavior, Hydrozoan Compatibility, Hydrozoan Selection, Hydrozoan Systems, Hydrozoan Feeding, Hydrozoan Disease, Hydrozoan Reproduction, Medusoids/Jellies (Ctenophores, some Hydrozoans, Scyphozoans): Jelly Identification, Jelly Behavior, Jelly Compatibility, Jelly Selection, Jelly Systems, Jelly Feeding, Jelly Disease, Jelly Reproduction, Fire Corals Lace Corals, Stinging-celled Animals

Re: Question about hermit crab growths  10/6/08 Thanks for the reply. I got a somewhat better picture of it, still not GREAT but hopefully helps you out a little more than the last one. Grant <Ahh, thank you for this pic... do look "Polypoid"... am more sure these are indeed Hydroids/Hydropolyps... There are many "kinds" as you will see... as long as these don't spread to your hardscape, I would count your Hermit lucky to have such a built in defense. Cheers, BobF>

Oh yeah

Purple Feather Weed? Could Be Feather Hydroids! 9/13/08 Hi Guys and Gals, <Hi there, Andrew> While snorkeling today (thank God it's warm enough to get in the water again!) I came upon this fascinating (to me anyway) feather-like organism. <it's neat looking, that's for sure.> I couldn't help but lift a small piece off the rock for an experiment in my 20Gal. <Were you wearing gloves at the time?> Tank is currently about 2 months old, cycled with 6Kg semi-cured live rock, and live sand. Ammonia, Nitrite @ 0, and Nitrate is at about 10 at the moment, <Just keep an eye on the nitrates, don't let them get above 20ppm.> temp steady at 26 Deg C, and salinity is 1.022 <Salinity's a little on the low end, but okay.> Stocking is 1 bicolour Dottyback, 2 tiny blue/green chromis, 1 even smaller yellow coral goby, 3 small hermits, and about 8 snails. All very happy in their current home. <Good> Which brings me to my actual question.... What the heck is it!? <I sincerely hope I'm wrong, but those sure look like feather hydroids to me (Family: Plumulariidae). If so, they're not the best addition to a system, to say the least. Also, after going in for a close-up, that red macro-algae on the right side of the rock looks very similar to a variety that can be invasive and very difficult to control.> I found it in full sun at a depth of about 9' (growing on a football sized tunicate) <Wow!> ..in a bed of sand held together with fine hair algae. It came away in a nice clump about 2" across. It now graces the front of a lightly stocked tank. Each "feather" is separate from the next, and grows just like a real bird feather would, <Yep> looking side on, you can see a single "tap" root about the length of the feather itself. <That long 'tap' root along with the unusual color is what's keeping me from being absolutely sure those are hydroids.> I'm pretty sure in between the main subject of the pic is some juvenile Dictyota, <It looks like a Rhodophyta/red algae of some sort, but I can't see it well enough to narrow it down further. Dictyota is a brown algae (Phaeophyte) that's usually green, yellow/brown, or even blue. I've never seen red. It could be something like Scinaia.> ..but cannot find any reference to the feather like growth (which I find most attractive), <I find it very attractive as well. By the way, I couldn't find any similar looking macro-algae in that color either - and I was hoping I would!> ..but am a little cautious of! <Good call! Hydroids can sting the living daylights out of you. Please see the information and species 'Gymnangium' half-way down this link (as well as associated links at the top): http://www.wetwebmedia.com/hydrozoans.htm Here's a good close-up of a feather hydroid. Note the similar, almost bumpy/broken appearance of the 'branches'. Those bumps are actually individual feeding polyps that have little stinging tentacles surrounding them: http://www.poppe-images.com/images/image_info.php?picid=929540 .> If you could help identify it, I would be most appreciative. <Well, I'm pretty sure those are hydroids, but I'm hoping Bob will confirm or deny.> I make an effort to Identify everything I can myself, <Good for you! Not only do you get the satisfaction of solving a mystery, you also learn quite a bit along the way.> ..but find it difficult to locate images on your site unless I know the name of the organism I am looking for. <See below> Is there an image library somewhere grouped in broad categories like fish, algae inverts etc. that I am yet to find on your site?? <Not a specific image library as yet, no, but it's been discussed. In the meantime, Bob has the site organized/sectioned off into topics that include many terrific articles with photos of representative species in the most commonly seen genera. Usually that will give you enough information to help narrow things down a bit. Here's the main page for marine topics: http://www.wetwebmedia.com/marine/index.htm . Just pick a subject, start with the articles for an overview (with photos) and go from there.> I would love to help myself in future where possible. <I'd try the above and/or use our Google search engine: http://www.wetwebmedia.com/WWMAdminSubWebIndex/question_page.htm > Thanks for your time. All the best. Andrew.
<You're very welcome, Andrew. Take care, -Lynn>

  Hydroid. RMF
Is this Ich? - 07/13/08 Hi crew - <Hello Joel.> Along with all of your other truly valuable services, I am very fond of your ability to educate me by identifying various biological life forms. <I'll give it a try.> I have a silver-tipped pulsing xenia that has been in QT for 21 days as of tomorrow <Very good quarantine practice.> , is pulsing quite happily, and I plan to move to the main display tomorrow as well. However, I don't know if these guys are tomonts or just some white filter feeder. <The latter.> These images are all at 10x magnification, and image 2553.JPG shows what they look like under normal viewing conditions. Any idea what they are? <Hydromedusae, also called hydroid jellyfish. See http://www.wetwebmedia.com/jellyidfaqs.htm.> I hope not tomonts. <Nope. Tomonts are even smaller. They are 300-500 micrometers and look totally different.> Thanks, Joel.
<Cheers, Marco.>

Sponge ID... uhh, worse  7/6/08 Hi Bob and Crew, Can you help us identify this thing (we think it's a form of a sponge) growing from under our Goniopora. All of our parameters have been good, we just noticed this one night when the Goniopora had gone in. Picture is at: http://photo.evasionoftruth.com/g1/aquarium/IMG_0849cropped Its directly in the center growing from under the frag disc. We are wondering if we should remove it, it appears to be a filter feeder as it does not retract when we touch it. <... is a Hydrozoan... and is stinging the bejeesus out of the Poritid... needs to be removed, scrubbed clean (with vacuuming if done underwater) entirely. Please read here: http://wetwebmedia.com/hyzoancompfaq.htm> Keep up the great work on the site, we use it daily to find out things about having a reef tank. Thanks, Buster
<Thank you for sharing Buster. Bob Fenner>

Help identifying 2 pics? 06/21/08 Dear wet web media, I have searched way too many hours on these things growing in our saltwater aquarium (120 gal). It's been established for a couple years now, but I am noticing these things multiplying recently. I've attached a pic of some of them. They seem to be mostly at the bottom of the tank on the glass. Their tentacles seem to move. <The pics are really too blurry to make much out... but from your description below, I'd say they're likely harmless Spirorbis worms.> In the second pic I have many tubes of different shapes. They seem to be growing larger. Some are long & skinny, where this one is kind of boot shaped with an obvious hole in it. <They look like sponges to me.> One thing I notice is white specs all over the glass at times. If you look really close they look kind of spiral shaped. I sort of think it looks like a snail (and I have hundreds of different sized baby snails that just keep showing up). Cold they be reproducing? <Could be... are these things stationary or mobile?> Thank you for your help.
<De nada,
Sara M.>

Re: help identifying 2 pics?   6/22/08 Just to clarify, I have two things I am trying to identify. One is the specks that show up on the tank glass, that develop into spirals. I'm just curious about these. Was wondering if they were snails reproducing. <possibly...> The one I am most concerned with is the tentacle like things that are multiplying on the glass near the bottom of the tank. Please let me attach one more pic that is a little more close up. Maybe you can identify it better. These don't seem to move at all, although the tentacles or arms (like hairs) seem to be alive & moving (not just with a current). They worry me that I should be getting rid of them. I probably have 20-30 of them that have developed in the last month or two. <Ah, now I can see them... looks like Hydroids. http://www.wetwebmedia.com/hydrozoanfaqs.htm> Thank you for your Kristie
Sara M.>

Ohh, Hydrozoans. B

Identification -- likely Hydroids -- 05/27/08 First off, thank you all for being so kind as to help identify a coral I have asked about before, and now have a larger image of so you can get a better look at the rooting/matting system of it. <Please send earlier correspondence along when mailing follow-up questions.> I have been told that this is anything from Hydroids to Clove Polyps, none of which I believe it is. <Add me to the ones saying Hydroids.> It grows really well. <Hydroids do so, especially nasty ones.> I took the first clump out in November, and here it is again creeping onto the rocks. <People have left the hobby because of these things.> It does not sting, and it doesn't suffocate anything that I can tell... <Can possibly hurt and eventually kill corals.> I really like it, but I don't want to harm anything, so if someone could please help to properly ID this, I'd greatly appreciate it. <Likely hydroids of the family Tubulariidae, possibly even genus Tubularia (compare to internet and literature pictures) or related. Should not touch sensitive corals, may become a pest or simply vanish someday within a short time. Cheers, Marco.>

Gorgeous pic. RMF

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