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>

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>

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