FAQs on the Hydrozoan Identification
Related Articles: Hydrozoans, Cnidarians, Fire Corals, Stylasterines, Hydrozoan Jellies,
Related FAQs: Hydrozoan ID 1, Hydrozoan ID 2, Hydrozoan ID 3, Hydrozoan ID 4, Hydrozoan ID 5, Hydrozoan ID 6, Hydrozoan ID 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,
strange new creature on glass 12/6/10
Dear WWM crew,
Firstly, thank you for your informative web site, love it!
Secondly - the reason for the email... Hopefully the pictures got
The first is when I found it, the second is two days later.
Seeing the PVC in the background, you can tell that it
doesn't move much, whatever it is.
We had a rough couple of weeks and I wasn't "able"
to change the water at all. Once I did a test for ammonia,
nitrite, and nitrate levels and saw bad news, I began to change
the water. One gallon at a time. I took the 55gallon tank down to
about half, moving the hammerhead coral to keep it submerged (by
the way, are these bad? I heard of stinging tentacles that come
out at night that kill neighboring fish and coral).
<Euphyllias can be tough on Cnidarian neighbors, physically
Read here: http://wetwebmedia.com/carycompfaqs.htm>
And slowly added water back in... again, one gallon at a time.
This little critter is still hanging out and moves a little bit
daily. I can't for the life of me figure out what it is,
where it might have come from. We have not added anything new in
at least 4 months, and that was a blue starfish. Our live rock is
all at least 1 year old in this tank.
Currently our water parameters are "okay" with nitrates
being at around 40 (ppms?)
<Mmm, too high. I'd keep, allow at half this
Another half water change in a couple days should hopefully fix
this. Salinity is between 1.021 and 1.022.
<... too low. See WWM re>
Temp runs about 76 degrees. We have about 30 pounds of live rock,
an inch or less of live sand. 1 brittle star, 1 cleaner shrimp
(red w/ white stripe down his body), 1 green mandarin (sp?), 1
<These spellings are correct>
4 green blue chromis', 3 mollies (looking for a new home),
and 2 false clownfish (that live very near the creature of the
glass). 2 snails, at least 4 tiny baby snails, a few mini brittle
stars, 4small hermit crabs. Only current filtration is a hang on
the tank filter (sump tank and protein skimmer are not in use at
Hope you can identify our little creature!
<Considering the size, growth (thank you for the two images),
the swellings at the growing ends and their extensions, lack of
motility... I do think this is a Hydropolyp/Hydrozoan species of
some sort. I would carefully scrape and vacuum it out during a
water change. Please read here:
and here: http://wetwebmedia.com/hyzoanidfaq.htm
Duncan Coral with Red "Thing" coming out of
its mouth 11/12/10
Thank you for all of the great information! Until now, I have
always been able to find the solution to any problems I have come
I have a Duncan coral which seems to have a red "worm-like
thing" coming out of its mouth (please see attached photo).
The "thing" is a couple of inches long and flaps with
the water current, but I just do not know what it could be. I
have had the Duncan for about 6 months and it has been rather
unhappy for the last couple of months. However, the baby head
(seen under the main head) is ok. I worry that the red thing
could be a worm.
I used to see a long thin red worm in my tank, with lots of whips
spreading everywhere. I called it a spaghetti worm, although I do
not know if that is what it was. I cannot say that I have seen it
for quite a
while. Is it possible that it could be INSIDE my Duncan wrecking
<Mmm, not likely a worm, but unfortunately, too likely a
Hydrozoan. Need a better resolved pic to be surer>
Any help and possible solution you can give me would be sooo
appreciated as I really think the Duncan is a beautiful
<Please read here: http://wetwebmedia.com/hyzoancompfaq.htm
and the linked ID files above. Bob Fenner>
DIGITATE HYDROIDS 7/6/10
Dear WWM crew,
<Hi there Bill>
Lately I've been seeing these little things in my tank,
mostly on my refugium (in the sponge) see pic below
They look almost transparent and if you magnify the pic 200%,
you'll see that they are kind of spiny (3rd pic).
I was told that they are DIGITATE HYDROIDS, is that correct?
<Might well be>:
Are these things harmful to fish?
<Mmm, well, they can be... in large numbers...>
I have no corals in my tank, just a FOWLR tank.
If so, how can I get rid of them? My tank is in it's 4th week
of going fallow.
<Most often such organisms are "transitional" in new
set-ups... in other words, they most often "go" of
their own accord. I would not do anything overt at this juncture.
Please read here for more:
and the linked files above. Bob Fenner>
Re: Aiptasia? ID, pix? 4/27/10
I now no longer believe them to be Aiptasia. In spite of the fact
that they are very closely spaced together and see through, the
actual tentacles themselves are very spindly, and they are not
many. They resemble see through fibers, like a fishing line but
far skinnier. On each anemone there are probably only eight or so
of these long but thin tentacles. Does this still sound like
Aiptasia to you, and if not any suspicions?
Apologies in advance for the many questions.
All the Best, Sam
Please send along well-resolved image/s. Bob Fenner
I forgot to mention that the tank is only about 2 months old, and
still has trace amounts of ammonia even after cycling. Are
<They are, unfortunately, very hardy>
Or will they simply die off soon?
<More likely they will spread>
P.S. Thanks for the quick response, it's very much
<No problem. Simon>
Re: Aiptasia? 2 megs pic?!... 4/27/10
<... let's see... You haven't searched before writing
us three times... or else you'd have known:
and the files above...
These are Hydropolyps... READ: http://wetwebmedia.com/hyzoidf3.htm
and the files above... Don't write before searching.
|Thanks for the ID
Thanks for the ID! I did browse through the archives and did see
the hydro FAQs, however I did not find that certain page. I found
the exact same species as are in my tank in one of those pictures.
Sorry for any
inconvenience. Cheers, Sam
<Thank you Sam. BobF>
little white dots 4/2/10
I have these little white dots that are on the glass of my tank. They
have a round center with aprox 6 little lines radiating from the body.
They look like microscopic snow flakes. I can not seem to get a good
photo of them
because they are so small. Do you know what they might be?
<Perhaps Hydropolyps: http://wetwebmedia.com/hyzoidf3.htm>
Once a Marine always a Marine.
<Aquarist? Maybe. Bob Fenner>
Aiptasia or Colonial Hydroids!?! 2/26/10
Hello Dear WWM Crew!
I found something in my Nano and to tell you the truth, I am
There is 4 little brown anemones looking things with tubes!
at first I thought of them being an Aiptasia, then colonial
<I think Hydroids/Hydropolyps, though not necessarily
I took a long toothpick and when I touched them the tube was hard
like a feather duster.
But polyp/anemone looking like Aiptasia (I did nuke a few from
<You might have both! You lucky pug!>
I am very sorry for the pictures they are so small that even with
my nose stuck to the glass I can barely see them.
I would love to know what they are before I pull out the needle
and start shooting!
You guys are the Greatest Crew ever!
Love the site
<Thanks, Bob Fenner>
Hydroid? (Nope'¦Syconoid) --
Greetings again WWM crew,
You have always been so kind and helpful.
<<Is our pleasure to serve>>
I just noticed a few of these in my pico tonight, and tried the
hitchhiker ID sites without luck. They are about 1/2 cm and they
are only under rocks in shaded areas. The small Zoanthids on the
left are for size comparison. If you tell me what these are, I
will search the web on how to best get rid of them.
<<Well Nick, if you are referring to the small white
spherical object attached to the underside of the rock toward the
upper right of the photo (I don't espy anything
else)'¦it's a Syconoid sponge. These 'can
grow' to a few centimeters in diameter'¦and are
harmless if not beneficial. No need to worry here>>
Thank you in advance,
<<Happy to share'¦ EricR>>
Confirmation of Hydromedusae
Please see the attached image I took of my 3 weeks old tank.
It's saltwater with 36 lbs of live rock and 20 lbs of live
sand, a cleaning crew and 2 fish. All water parameters are dead
on perfect from the advice I've got at the LFS. At first
there were just a few of these little guys on the glass of my
tank and they seem to multiply quickly but don't take over
too bad in between the 3-4 days between Mag-Float cleanings. They
don't seem to be hurting anything but my view :-)
So are these, in fact, Hydromedusae?
<I do think so>
<Please read here: http://wetwebmedia.com/hyzoidf3.htm
and the linked files above. I would be patient here... Likely
these will cycle out of their own accord. Bob Fenner>
Unknown ID, No Pic -- 12/16/2009
<Hey Sara, JustinN here!>
I was just wondering if you could help me with some new critters that
have appeared on my glass.
<Mmm, not likely without a picture to assist, but will try.>
They're circular in shape, a little bigger than the tip of a ball
point pen, and opaque. Tentacles that move like an anemone. Could they
be Aiptasia spores?
<Not likely, in my opinion>
I do have one Aiptasia in my tank, and I've seen babies before, but
they've had more of a "stalk" shape.
<My thoughts exactly -- Aiptasia has a distinctive appearance -- the
stalk is a big part of the morphology.>
These critters are flat (well they seem flat maybe because they are so
<Without a picture, its very much a shot in the dark, but if I had
to guess, I would assume hydroids. Have a read here:
http://www.wetwebmedia.com/hydrozoanfaqs.htm and related
<Do send along a quality picture, if possible -- this will aide in
identification. Good luck! -JustinN>
Re: Unknown ID, No Pic -- 12/16/2009
I found out what they were, through the use of your website (which is
amazing by the way)
They are Staurocladia/hydromedusae.
<Excellent! My theory was on par... I tend to not be the best on the
identification front, so that makes me happy :)>
Also found that I have Munnid isopods and Corallimorphs...again, why
your website is so amazing.
<Glad we could help! -JustinN>