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FAQs about Sea Urchins, Sand Dollar Selection

Related Articles: Sea Urchins

Related FAQs: Urchins 1Urchins 2Urchins 3, Urchin Identification, Urchin Behavior, Urchin Compatibility, Urchin System, Urchin Feeding, Urchin Disease, Urchin Reproduction

Black Long Spine Urchin Questions       9/17/19
Hi Bob -
I have two questions for you. I've searched the wet web media knowledge base but haven't found the answers. FYI, I've been working on eradicating cyanobacteria from a 265 gallon and 150 gallon (both FOWLR) with the methods you've outlined. Progress is occurring.
<Sure and steady is the way here. Fast approaches are dangerous; too often lead to anomalous losses to wipe outs>
Questions: Would a black long spine urchin eat cyanobacteria?
<Some, yes... do look (Google?) the genus Diadema re>
I suspect not, but not 100% sure. Lastly, would a green bird wrasse bother a long spine urchin?
<Doubtful; no>
I know they like snails, but thought maybe the long spine urchin would be OK with its venomous spines.
<This genus of urchins, not very venomous... mild; not harmful to humans.>
Thank you, John
<Welcome. Bob Fenner>
Re: Black Long Spine Urchin Questions      9/18/19

Perfect! Thank you Bob!
<Ah, welcome John. BobF>

Urchin compatibility   2/1/18
Hi, I was wonder which, if any, sea urchins are compatible with a common starfish in a 75 gallon tank? Thank you :)
<Most all are; though I hasten to mention that some urchin species choices are better than others. See WWM re the Echinoids. Bob Fenner>

waters on Cape Cod; diving for Mespilia in the wrong sea      3/7/14
Hello everyone!
This post / question will be different, I'm sure, and I hope you can answer it!
I live on Cape Cod Mass and my 75 gallon reef tank is totally smothered with GHA!
And yes, I have tried everything  possible to rid the system , using tons of advice for the past 9 months!
Last resort, Tuxedo Urchins Mespilia globulus.
The problem is, I am totally out of money,..BUSTED!
If I were to dive into the waters here on the Cape, where would I find them, if at all?
<Ah no... are tropical... in the Indo-Pacific. Nothing you could/would find there will really do well in a heated system... possibly w/ the exception of life swept up summer-seasonally from the south>
Hopefully, not too far down, as I can only hold my breath for about one minute!
I'm serious!
<Turn the lights off for now. Save up for a good scavenger. Bob Fenner>
 Re: waters on Cape Cod      3/7/14
So glad I found you at the helm Bob,...lights  are off! Will keep you
posted, ........hold your breath, your lungs are more advanced than mine!
<Well; more aged. B>
Like a good cheese!

Question about urchin  12/7/11
To whom it may concern,
<Hi there>
I was told about an urchin that is from the Pacific Ocean that is known to devour coralline algae.
<There are several, from the M.E. meaning "many">

I was told it is called an impact urchin.
<"What's in a name?" BillyS>
 I believe they are purple in color.  Is that the correct name?
<Common names are always correct Johnny>
 If not what is the correct name and what is the scientific name? Look forward to your response.
Christopher Faiola
<Me too. Let's see... I'll use Google... "impact urchin pacific eating coralline"... Oh! The fourth listing... on WWM, try this. Bob Fenner>
Re: Question about urchin  12/7/11

So where is the answer at? I don't know what you mean by fourth listing on WetWebMedia.com
<Mmm, sorry re the lack of clarity. The fourth listing on Google, given the search string I supplied. I don't know what an "impact urchin" is... BobF>

Synapta maculata/Sea Cucumbers 11/1/10
<Hello Chad>
I have a few questions regarding this species (Synapta maculata) as I can't find much info about it from my typical sources. I have a 225 sps/lps reef w/ live sand (3-5 inches) that has been up for almost 4 years. Doing very well in fact. I have been seeing a few of these (sometimes w/ commensal shrimp) pop up on sites and was wondering if my system was appropriate for their care. I have a few other "tiger tail" cucumbers which seem to be doing well. Anyways do you think they would fare well in a typical reef aquarium w/ live sand?
<If you already have a few Tiger Tails, I wouldn't add any more Synaptids to the system, food supply may dwindle.>
Do they need supplemental feeding beyond standard detritus? If it died would my tank succumb to "wipe out" syndrome? Any other tidbits of info.
<Mmm, look here. http://www.wetwebmedia.com/seacukes.htm>
Thanks for your input.
<You're welcome. James (Salty Dog)>

Yellow or Tigertail Sea Cucumber and Tuxedo Urchin, sel.  11/15/08 Hi again! Ok, so I have another question: Which is better for my 24g? A Tigertail or Yellow Cucumber? <Um, neither? 24g is just too small for these animals (imo). I did some looking around on your site, and apparently these are some of the best (attractive/display) cucumbers to have in a tank. Right now, I'm leaning towards a Yellow Cucumber due to its small size, but because of the lack of water volume, I'm worried that it may be too toxic for my aquarium to handle. <That, and, these animals have feeding requirements that make them poor choices for small tanks.> Also, will the Potter's Angel (which I mentioned in an earlier post) pick on it? What about a Tuxedo Urchin? Would it bother one or both of these animals? <Likely not... but again, Urchins are usually better off in larger tanks... with more to feed on. In small tanks they also tend to cause trouble by knocking things over.> And how compatible would they be with my Red and Blue Reef Tip and Blue Banded Hermit Crabs? The only one of my hermits that has ever caused any sort of problem is my Blue Banded Hermit, which ate two rather unhealthy (they had moved under a small rock for some reason and stayed there) Florida Ricordeas and left my healthiest one alone, despite all of them being right next to one another. I've had it (the crab) for a while now and no other problems with it have ever arisen. Does this mean that as long as the cucumber is kept healthy my crab will leave it alone? Or is it best not to risk it? <I would look into animals better suited for "nano tanks"... though 24g would be considered a "large" nano tank (oxymoron, I know), you're still quite limited in what you can keep in such a small tank. http://www.wetwebmedia.com/smmarsysstkgfaqs.htm to start.> Thanks so much for your help! <Best, Sara M.>

Sand Dollars, sel. , Angel Behavior/comp. 9/30/08 Hi, <Hello> Thanks for all your help you have given in the past! Just a few questions...can you use sand dollars for tank decoration?? <As in the dried skeletons? These can be used but may dissolve over time and will likely look more like flat pieces of live rock after a while. Live sand dollars will starve in all but the largest tanks.> How can darkness or a week or two without the lights on be beneficial to your fish?? Just wondering, I am having to turn off the lights for a while until my B/G Algae dies off some. I read that this can be beneficial to your fish. <It can lower stress for fish in a new environment, but overall I think it's effects are negligible as long as there is enough light for them to see with.> Will a Koran Angel (4" Juvi) eat Zoanthids, or crocea clams?? <I would not trust a Koran with either of these.> Thanks for all your knowledge! Your Great! Dawn <Welcome> <Chris>

Echinometra viridis - 8/31/08 new urchin added to tank, sel. Hello: <Halloa!> I bought a new urchin a few days ago, called a short-spined urchin at the LFS, which I, of course, had to identity via your awesome website as a Echinometra viridis. <A veritable bulldozer of an echinoderm> I have a 29-gallon fish only tank with a lovely "fake reef" which you can see here, if you are so inclined: http://www.petsmart.com/product/index.jsp?productId=2752285 . I have that thing in the tank along with 40# of aragonite substrate with lots of shells, etc. in it. The tank is in my fireplace, actually, so I don't have room (or the desire) to go with the lighting needed to do live coral, etc. Live rock is not my gig either. In the tank I have 2 Perculas, 1 Royal Gramma, a cleaner goby, a Pink Spotted Shrimp Goby, and a cleaner shrimp. I also have 1 blue and 2 red-legged hermits. The reef only takes up about 1/2 of the room in the tank, and has lots of nooks and crannies, so everybody is happy and there's lots of free space in the tank as well for swimming, crawling, whatever. <Sounds good> Anyway, now that you have a visual: I was looking for an algae eater to help with cleaning. The Spotted Goby, who we've named Creature, insists on picking up the hermits and dragging them to his little cove to decorate. He drops them and then takes off to go find some ledge to hang his head out of and lay on, so no one's being injured. I've added two Emerald Crabs, and both, within 2 days of adding, I've found upside-down, dead, in Creature's little area. Hm. They obviously aren't supposed to be picked up and dragged and then dropped indiscriminately like a dirty sock. So, the LFS guy suggested I get something a bit harder for him to move, such as the urchin, to help keep the tank clean. <mm...not my first choice> Here's my question: (finally!) Is this particular urchin going to work out OK in my tank and will he do what I want him to do? <There is a chance he will...but I would return him> He has a little hole that he stays in during the day and seems to be quite content so far. I was told when I bought him that he is great for algae and would work perfectly in my tank. Now, I'm sure Mr. Pet Store Fish Guy is very knowledgeable, but I have to wonder, did he give me bum info? I was hunting around on Wet Web looking to see if you guys recommended this particular species for anything in particular to anybody in particular, and found nada. Also, I saw something about if they die, so does everything else in your tank. This is no bueno! <?Verdad! A bigger problem is that this guy is by no means nimble, nor the best choice for an algae remover. He'll also destroy that artificial rock faster that you can say "radula"> Really? I don't have a 500 gallon tank here, so If he croaks, how much time do I have to notice and remove him? Is he worth the hassle, or no? <Not in my opinion> If Creature would stop dragging my cleaning crew around, I'd have more options. I've asked him repeatedly to stop, so please don't suggest that I have a talk with him. <Can't we all just get along?> The best I can get is that if I see him eyeing a crab, I walk up to the tank and he backs up. However, the SECOND I turn around, he's got it and heading for his little cove. I don't want to get rid of him because he is highly entertaining, but I also could do without the algae issues. I'm also going for a very peaceful, "no eating each other" tank here. <I'd recommend getting your hands on some good algae-eating snails- Turbos, Asterina, or Stomatellas if you can find them (for these latter- which are excellent and quite attractive- you'll probably have to find someone to buy/trade for them)> Thanks in advance for your help and enjoy the holiday! <No problem!> Shelly <Benjamin>

Distributors and species names: Regional variation. Urchin sel.  6/13/08 Hello, WWM crew. <David> I am hoping that with some of your people having experience with the distributors in the Pacific that perhaps they will know something about this. I have been trying to get an Astropyga radiata via my LFS, but the two times he has ordered one (or three), what have arrived were Tripneustes gratilla. The second time he even sent a picture of what we wanted. The two species don't look that similar, so I'm left with wondering if there is some common name that those in the eastern Indian Ocean / western Pacific Ocean call this urchin, because the scientific name isn't doing it. Any thoughts? <Mmm, yes... for one, the trade is composed of "disparate players"... the actual collectors/divers are not often in the employ of the folks who gather, sell, ship livestock... So there is likely a disconnect here. Astropyga are rarely "used" in the trade, owing mostly to their long spininess... and difficulty in shipping therefrom... costing more to put in larger bags, screened, with more water (shipping is more money than livestock per se in most cases). Whereas Tripneustes are more compact, easier, cheaper to ship... Both animals are not that rare in the wild, easily collected. At any length, what I suspect is that these two influences, the fact that you're not communicating with the actual collector/s, and the social inertia of folks dealing with the Tripneustes is working against you. I would keep sending the images, asking whomever you're dealing with, to show same to their source/collectors. Bob Fenner> Thanks in advance. David

Hair Algae Vs. Our Urchin 10/14/07 Hello! <Hi there!> We have a 125 G. reef tank, 1 hippo tang, 1 blue damsel fish, 2 clarkii clowns, 1 clam, lots of corals: Zoas, Monti caps, frogspawn, hammer, SPS, etc. Oh and 5 pyjama cardinals. Anyways, several months ago, we brought home some LR we bought off of a guy that was downsizing. Big mistake. We no longer have bubble algae (different story), but we have hair algae, which came on the LR we bought. We figured that it would be no problem to get rid of what was left, after most of it was scrubbed off. So now there is a hair algae problem in the tank, along with Cyanobacteria. It seems that the hair algae is slowly receding, but the Cyano is becoming more prevalent. We have a pencil-urchin, maybe 3". We also have lots of snails, emerald crabs & hermit crabs. Suggestions on eradicating the rest of the hair algae & the Cyanobacteria? <This is more than the rock introduction. Yes the rock can introduce spores of nasties like hair algae and other unwanted guests, but nutrients need to be present for them to flourish. The use of Activated Carbon and an iron based phosphate resin will help dramatically over time. The resin should be changed out every 30 days. An increase in water change schedules will help also.> Every few days, we use a turkey baster to blow off the LR from the Cyano & push it into the sump & thus filter it out. Yeah, this hasn't helped. We use RO water for changes. We've also recently added a larger sump, about 75 G, for a total (approximate) water volume of 200 G. The pH is maintained at 8.2. Alkalinity is normal. Dose phytoplankton. once a month. Haven't supplemented the tank with Kalkwasser for a while (used to have it in a separate dosing tank). <The use of a dual DI canister after the RO unit will bring the TDS (total dissolved solids) to zero. This will help in reducing any nuisance algae. Returning Kalkwasser to the system will aid in the precipitation of phosphates and increase Calcium levels. I would return to dosing Kalkwasser.> Do we need another urchin? If so, what type? We've tried lawnmower blennies, but they seem to love to commit suicide by jumping out & attracting our cats, who, in turn, love to chomp on them. After much searching, it doesn't seem that this precise case has been covered on WWM, and so have decided to post this question (actually these questions.) to you! <The use of the Black Long Spined Sea Urchins of the Diadema family work very well. Orange Scribbled Rabbitfish are also very good herbivores but are hit or miss on small coral polyps. It's worth a shot.> (Yes, just for you, as we know you have nothing better to do) :-) Thanks all! <Bob and the Crew appreciate your confidence! Thanks Rich-aka-Mr. Firemouth> Anna & Eric Z

Purple Spined Sea Urchin... Arbacia punctulata   7/30/07 Hi Crew. <Hi Rick, Mich here.> I was walking the beach in Florida the other day on the Gulf of Mexico side and found a purple spined sea urchin. <Lucky you... the walking on the beach part... I seem to be good at finding urchins with my feet! Ouch!> I did a web search on them and they are, according to them Arbacia punctulata- purple spined sea urchin. <Is endemic to Florida, and generally live on rocky bottoms as opposed to sandy bottoms.> I was thinking about putting him in my FOWLR tank. Is he safe? <Mmm, I doubt that you will be able to provide suitable nutrition for him. These animals typically eat sessile invertebrates which he will likely consume your current tank population quite quickly. Gut content analyses have show bryozoans, hydroids, barnacles and tunicates and limited algae. The algae are typically only those growing on the rubble. but the diet is usually more heavily weighted with animal matter> I have a coral shrimp and a tang. goby and clown. Right now I have him in my QT tank. Would he benefit my tank? <I don't think the tank would benefit nor do I think it the urchin would benefit. I think it would be best to return him to where he was found.> I also found some large hermit crabs, about 2 1/2 inches and was wondering if these would be good substrate cleaners? <A big no go there! Usually any large hermit crabs are highly predatory, capable of killing fish and even well protected animals such as urchins.> Those I didn't bring home <Wise.> but the urchin was too pretty to pass up and they do sell them locally. <I do not have personal experience with this species, but from what I have read, I obviously have concerns, perhaps those in your local market may be able to guide you better, but with the information I found describing the typical diets of these urchins, I would be concerned about starvation. More here: http://www.int-res.com/articles/meps2005/295/m295p171.pdf > Thanks for all info past and present you guys are great and make my hobby so much easier. Rick <You're welcome and thank you for the kind words. Mich>

Algae Control, Urchin selection 6/22/07 Chris, <Hello> Thanks for your quick response. <Sure> I had a follow-up question. <Ok> While my 110g display is running fallow, the algae is starting to grow and grow and grow . . . This was all being kept in check by my lawnmower blenny and yellow tang before I removed them to the HT (neither survived). I have lots of hermits and snails, but they aren't really doing much. <Can be picky eaters at times.> Someone has suggested an urchin to control the algae, but I'm wary of that because I intend to introduce a few easy-to-keep soft corals once I get everything running and back into shape. <Some can be troublesome with corals.> Are there urchins that are reef safe, or do you suggest some other organism to help control algae during the fallow period? <As always I suggest the main organism for algae removal is you, manual removal will help lots here, both removing the unsightly algae and in the same step remove fuel for future algae to metabolize. But there are some urchins that can be utilized here, although bringing problems of their own. Some may sample corals while just about all are known to be bulldozers, knocking loose corals are rocks about, not particularly agile creatures for sure. Several suitable species are available, specific species are found in the FAQs.> Btw, in searching the urchin FAQs I came across the picture of the yellow goby with an urchin spike through its head. That is one of the coolest pictures ever. <Quite, although not a great day for that goby.> Although my tests show 0 phosphates, I imagine that there are some phosphates present--just being used up by algae before they register on test. <Yes, most likely.> I'm saving for a RO/DI unit, which should help in the long run, but until then I have ordered some PhosBan to run in the sump. <The RO/DI will probably help more than any livestock you add to the tank. I would probably not spend the 20 or 30 dollars on the urchin and apply it to the RO/DI unit, more long term benefit here.> <Chris>

Urchin for algae control   6/16/07Hello, crew. Here for a post-research sanity check prior to purchase. <Okay> I have a 20 gallon tank containing a very happy and vigorous peacock mantis shrimp (4"). Despite frequent (usually weekly) five gallon water changes, I am struggling to fight off amazingly vast quantities of hair algae and Cyanobacteria. Presumably this predator's messy feeding habits are more than this tank's nutrient exports can handle. The tank has a productive Remora skimmer and a small hang-on-tank refugium with a mud/sand substrate, live rock rubble, and Chaetomorpha (harvested biweekly). I also employ mechanical filtration with PolyFilter and PhosGuard. The total water turnover in the tank is > 20x/hr. Lighting is about 80W PC (50/50 10K and actinic). I have yet to try black-out periods with the lights due to the presence of soft corals (xenia, mushrooms, zoanthids) that I understand are significantly photosynthetic. <Mmm, yes... Does sound/read like a very nice small unit... and I concur, with much more nutrient than the gear can outcompete pest algae for...> I added a serpent star, which adds some movement to the tank, but hasn't done much else. I am strongly considering adding an urchin to try to attack some of the algae. I think an urchin has a good chance of survival due to the mantis' diurnal habits (and the urchin's nocturnal ones). <Good point> Snails/hermits are just so much aqua-popcorn. Food will NOT be a problem -- the tank looks like a jungle despite all efforts. After reading a lot, I am debating between the "Purple urchin" (Echinometra viridis) and the "Blue tuxedo urchin" (Mespilia globulus). Both are relatively small, are purely herbivores, etc. I am leaning towards the former, because it appears from what I've read that it will leave corallines more-or-less alone (at least, more so than the tuxedo). Also, it looks like the tuxedo is a little more picky about its habitat ("shade areas" are rather sparse in my tank). Do you guys think this might work? Thanks, Dan <Well... worth a try... I like the Mespilia for looks... Bob Fenner>

Collecting Sand Dollars... Best Left at the Beach.  - 6/7/07 If I bring live Sand dollar from the beach, and quarantine it, can I put it in my reef tank? <Greetings, Mich with you tonight. Can you or should you? Sand dollars generally don't do well in home aquariums typically starving after a few months. They require a lot of sand, approximately 10 sq ft of surface area for a sand dollar 4 inches in diameter. They also need a sand bed at least 4 inches deep, and can be suffocated by fine sediment and aragonite sandy muds found in some reef aquariums. Subtropical sand dollars will not survive at normal reef tank temperatures either. Generally, I think it's best to leave the sand dollar at the beach. Though I am glad you mentioned the quarantine part! Mich>

Re: Collecting Sand Dollars... Best Left at the Beach.  - 6/7/07 Thanks Mich. I'll leave them at the beach! <Welcome! Another dollar saved! Yay! Mich>

Urchin in Mud Refugia/Sump Area?   3/1/07 Dear Bob, <Actually Adam J with you tonight, hello.> Can a pencil urchin survive in a mud sump environment. <Urchins are largely rock dwelling in nature, but with some rock for hiding, etc.., a light and food source I don't see an issue. Though I would surmise it would partially be an unwanted organism in any type of refugia. Not only being clumsy and destructive but being an opportunistic omnivore, feeding indiscriminately on algae and other benthic life forms.> I have a lot of algae growing in there <Why are you concerned with algae in your sump/refugia area...is this not it's designation...would rather in colonize here than is the display or this refugia intended for other types of life?> and could use the hitchhiker to keep it clean, <If it is filamentous algae, smaller less destructive herbivores such as small snails would be a far better choice.> Also will the Aiptasia anemones harm the urchin? <No, though a large population of Aiptasia is usually indicative a larger nutrient issue.> Best regards, <To you as well.> Jason <**AJ**>   

Mespilia globulus   11/19/06 I have a 25 gallon with 12 bumble bee snails, a Hawaiian feather duster, a colored feather duster, an Arabian Dottyback, 12 dwarf blue leg hermits, 5 Nerite snails, 5 Tonga snails, a Bi-color Blenny, and 5 Scarlet hermits. I'm planning on adding a Fire shrimp and a cleaner shrimp. <Only one or the other... and not a Stenopid...> I've been looking into a Mespilia globulus. Do you think it would be compatible with everything else? <I would not add an Urchin of any species here... too small a volume, too crowded with organisms that fill about the same niche> What about some small mushrooms? <Could be tried> I've never kept them before but was thinking about them as well. My tank has been running for 10 months and has a large amount or algae growth (I just added the blenny and the Scarlets). <Ahh. I would wait on them...> Parameters are good, and filtration is high (Emperor 280, SeaClone 100), 2" sand bed, and standard fluorescent lighting. Rich Chen <Bob Fenner>

Algal control (Phaeophyte) via Echinoids  10/24/06 Hi, <Hello> One of my friend have a reef with a lot of algae (Lobophora variegata) he would like to know which urchin would be the best for eating these alga : Mespilia globulus or the Diadema setosum? thanks! <I would go with the Diadema species if this tank has space, a suitable mix of (non-pin-cushion) species. Bob Fenner>

Urchin question   8/20/06 Hello WWM Crew, <Sara>     I have a few of questions regarding a Lytechinus variegatus urchin ( I was able to id from your site), I hope you can help me out with. My first question is if a Lytechinus variegatus urchin is in the process of dying, or not doing very well, is there any chance it could release toxins in to my tank? <Mmm... yes... this species is a member of the Family Toxopneustidae... toxic to even the touch... to fishes, humans> Should I remove this urchin from my main tank? <Unless it were very large (hundreds of gallons), exceedingly well circulated and filtered I would not introduce a member of this family>   I had noticed that my urchin had been losing spines at an alarming rate recently and had stopped moving around the tank. When I turned him over there was a brown/tan worm on him. This worm was not a bristle worm, rather it looked more like a common earth worm (only much, much smaller.) It had small bristles on it's side, but the bristles were not near as large as a bristle worm's. <There are actually thousands of different species...> I also have noticed that there are deep red spots on the outside of the urchin it almost looks like blood.   After I removed the worm from the urchin he immediately improved and began to slowly move around the tank again.   So, I guess my main questions are should I remove this urchin from my tank and quarantine him? <Yes, I would. Don't use your hands in contact... scoop into a container... i.e., don't expose to the air...> Is there any risk he will poison my tank if he dies or is dying? <Again, yes> Lastly, are there any know worms that are parasitic to urchins, or was this worm just a result of him dying/not doing well? <Could be either/both>      Thank you so much for your help,   Sara <Welcome. Bob Fenner>

Tests of Dead Cicarid, Spatangoid or Clypeasters Available? Looking for Regularia and Irregularia!   7/2/06 Hello: <Hi there> I have a project that requires tests (spineless preferred, but I can remove spines) of dead heart urchins and cidaroid regular urchins.  I need to purchase specimens about 1.75 to 2.00 inches in maximum length/diameter.  I only need one or two specimens of each type.  If you have some that have died on you, or are a supplier of dead tests, I hope that you keep me in mind.  My project involves filling hollow tests with a fine plaster, and then molding the exterior of the specimen, so the specimens should be intact.   Thank you for your consideration. Jon Branstrator Professor Emeritus Geosciences Department Earlham College Richmond, IN  47374 <Mmm, I do know where to look, ask next. Am CC'ing Marty Beals, friend, owner-operator of "Tideline" in the Los Angeles area. He will likely know where to seek these out. Cheers, Bob Fenner>

Buying Echinoid tests ("shells"/bodies) 7/30/05 were could I Buy sea urchin tests of exotic urchins like Asthenosoma or  diadema urchins. <Hmmm... this would be a good question for a science teacher. Do check your local schools/universities for a friendly instructor that can point you to a dealer. But in the meantime, I might look at North Carolina Biological Supply. Famous suppliers of science supplies/products. kindly, Anthony> <Do also contact Marty Beals at Tideline in Los Angeles re. RMF>

Pin Cushion Urchin partially eaten by Chocolate Chip Starfish I recently introduced a purple pin cushion Urchin (I think it is a Strongylocentrotus purpuratus) into my system. <I hope not... this is a cool/cold water species> Last night I came home to find my chocolate chip star treating him like a happy meal. There is a 1/2 inch section on the Urchin where his needles have fallen off or been digested. I have removed the star fish from the system and placed him where he can do no harm. The Urchin is understandably stressed and has not moved much (but it is still alive). My question is does this guy have any hope of survival and what can I do to enhance his odds of visiting the big reef in the sky? <Mmm, really just keeping the system, water quality optimized and stable, providing foods...> Thanks in advance and this web-site has been and continues to be invaluable. -Rob Glentzer <Rob, do try to ascertain the species here... Ask your source for its identity, look over WWM re... CCS are "not detritivores"... Bob Fenner>

Calcium and Urchins 1/11/05 No sea urchins in the tank I find them to be quite destructive on the corals. <this is a common and mistaken reputation of urchins because the wring urchins are usually purchased (rock boring short spine species, pencil urchins, etc.). The best Urchins are Diadema... totally reef-safe, nimble, do not eat much or any corallines, superb algae grazers, etc> So what in you opinion is the best type of calcium to dose with, excluding calcium reactors... <common calcium hydroxide... its time-tested and true with more benefits than any other form of calcium. Read more about it in our archives at wetwebmedia.com> had a bad experience with them once.. do not what to have that again. <its sounds like you knee-jerk react too easily my friend. Just because you've been given bad advice about urchins and calcium reactors, doesn't mean they are bad themselves. Calcium reactors are the single best and most reliable way to dose calcium and raise alkalinity in reef aquaria> Bryan <best regards, Anthony>

Re: Calcium and Urchins 1/12/05 Antoine to JamesG To help a bit on that question and for your future reference, mate... your urchin guess was a bit of a long shot, Most urchins are quite useful (critical on the reefs for algae control and  useful in aquaria). A few of the mismarketed species are cheap and abused... pencil urchins lean carnivorous (grazing benthic animal matter more than algae), and a few of those short spine black urchins (Echinometra and the like) are rock boring! And yes... graze corallines. But a bevy of others are very useful and reef safe... not the least of which is Diadema for tanks big enough to let one grow out. Their problem is/was lack of corallines though... and one great, reliable solution is Seachem's liquid calcium (polygluconate). It is... heehee... useless for coral growth IMO, but (!) it is simply outstanding for growing coralline algae rapidly. You have my promise that most aquariums that gets a 3 month dose of this cheap calcium will be swimming in calcareous algae! FWIW Anthony :)

ISO Lytechinus variegatus 5/7/04 I'm a marine biologist working at the ULB in Brussels, Belgium, and would want to buy 10 Lytechinus variegatus from a licensed dealer. The problem is I can't find any. Do you have a list of dealers in Europe, preferably in Belgium, selling these animals? Cheers, Herwig <cheers, my friend... I have cc'ed a good friend of ours, Steven Pro of Pro Aquatics, here in the USA. While I have no knowledge of a specific dealer in Europe for these urchins (although I suspect if anybody would have them, it would be The Marine Centre in England), Steve is an aquarium service professional that has worked with a local university for many years on keeping and purchasing this genus for research. Perhaps he has some information or contacts to share. With kind regards, Anthony> Herwig Ranner

ISO Lytechinus variegatus II 5/7/04 We got this species through a company in the US called Carolina Biological.  This was not my choice, but the University had some sort of deal already worked out with them, so it was out of my control.  I would imagine any tropical marine ornamental wholesale company that deals in Atlantic specimens could get these for you.  The Marine Centre sounds like a fine place to begin your search. <grazie, Steve... and congrats again on the birth of your second daughter :) Anthony>

Sand Dollars (3/28/04) Hi, <Hi. Steve Allen tonight> I live in Jacksonville, Fl. and picked up (2) live sand dollars at the ocean. <Bad idea. Can you put them back?> I was wondering if these would be okay in a 55 gal. aquarium. <No. Even with a deep, live sand bed, it is virtually impossible to keep sand dollars alive in an aquarium. The odds that they will die in your system are over 99.9%.> Thanks, Dwight <Please put them back if you're close to the ocean.>

Urchins and Mantis Shrimp in LR (3/5/04) Hello guys <Steve Allen tonight> Hey thanks for all the help I need it! <We all do.> My son just stopped by to see my new reef tank and told me that I need to rid myself of all the black urchins in my tank. <Did he say why?> They came in with my live rock. Are they a problem in a reef tank? <What sort of "black urchin" are you referring to? Diadema species? Read here about urchins: http://www.wetwebmedia.com/urchins.htm The biggest problems are their venom, their occasional knocking over of live rock, and the possibility that they might eat all of your coralline algae. Read the articles and the FAQs and you ought to be able to decide what you want to do.> Please tell me what's so bad about Mantis Shrimp I guess I have a lot of them too! <Have you seen them? Here's a starting point where you can learn all about the problems people have with these aggressive, voracious predators: http://www.wetwebmedia.com/marine/inverts/arthropoda/stomatopods/mantisshrimp.htm > Thanks Kirt <Hope this helps>

Beginner Sea Urchin Hi! I was wondering if there is a sea urchin that you might recommend as a beginner's species? I have a 65 gallon fish/invert system with several hermit crabs and starfish. There is not much algae in my tank, I believe due to low light levels. Does this preclude any species of sea urchin? Are there ones that are better scavengers than other? I am interested in the Mespilia globulus and Eucidaris tribuloides. <I think the Eucidaris is going to be your best bet. They do not eat exclusively algae, which is bad for reef tanks, but good for your situation. You should be able to feed it a variety of meaty items and keep it healthy. Please take a look here http://www.wetwebmedia.com/urchins.htm for additional information.> Thanks, Steve Thornton MD <You are welcome. -Steven Pro>

Tuxedo Urchins Hi Guys ! I have read that tuxedo urchins do a good job of pruning hair algae......and that is STILL my biggest problem in my 300 gallon reef tank.  Although my new skimmer (Aerofoamer 848) that replaced my ETSS 1400 is doing a great job (algae is beginning to die off after 2 weeks of new skimmer operation) I still have been siphoning out a lot of hair algae.  This garbage has killed many of my beautiful hard coral frags and some larger colonies    ;-(  ......  I also read that this particular species of urchin is smaller than most and is less destructive than most as far as plowing things over. Anyway, my question is:  Would it be wise or appropriate to introduce a tuxedo urchin into my system at this point to help with the hair algae extraction  (PLEASE , please say yes ....manual extraction is a pain !) ? Or are there any negative consequences that would outnumber the advantages of this algae eater ? Thanks,  and I love Anthony's book ! <Me too> Chuck Spyropulos <Hey Chuck, you could give this Urchin a shot, but I would feel better if we got down to the bottom of what is causing this algae, there is a ton of info on the site. http://wetwebmedia.com/algaeconMar.htm They will dine on algae nuisance or otherwise, and would have no problem poking and knocking things over. http://wetwebmedia.com/urchinfa.htm  - Best Regards, Gage>

Urchins III Unfortunately that wasn't much use, or perhaps I was too vague. Would Mespilia eat macroalgae as well as microalgae? <Your macroalgae are probably safe.> *Does this include calcareous macroalgae (Halimeda, Penicillus)?* <<More than likely, they would be safe.>> The page says that corallines are eaten but does not mention macroalgae. I understand Mespilia to be safe with sessile invertebrates? <No urchins are completely safe with sessile invertebrates. Urchins are the bulldozers of the aquarium and can/will knock over just about anything. This would include your corals.> *What about if I used Milliput to secure the corals to rocks? Is that very effective to stop them being dislodged?* <<I don't know what "Milliput" is, but I am going to guess it is some sort of epoxy. That should hold the corals in place, but not protect them from getting jabbed. Many LPS or soft corals could be damaged from the spines.>> *I hope these questions are not too silly, but I just want to make sure. I think the snails are doing a good enough job with the green microalgae on the rocks and glass as it is!* <<If you really do not want or need the urchins, perhaps you should reconsider their addition. -Steven Pro>>

The Urchin's New 'Do (Pt.2) What would I do without you guys? <Hey- What would we do without YOU?> A quick search for Bryopsis on google netted enough photos for confirmation. I would just pull the stuff off, but I've heard that removing a Tuxedos camouflage can damage their tentacles (the proper name for their "tube feet" has slipped my mind). I tried to remove the few strands he had when I purchased him a month ago, but after dislodging the urchin before any algae come off I figured best to leave it alone. Any ideas? <I agree- just leave it alone. I'd only pull this stuff out from areas in the tank where it's becoming a problem. It will probably do more harm than good yanking it off of the urchin... > Now, you have me concerned that my skimmer is not producing cups full of junk weekly. Please review my specs and let me know if there is something I am missing. Skimmer produces about 1/4-1/2 cup of the worst smelling stuff weekly, and I do weekly 10g changes with RO and Instant Ocean. Over the past 4 months since setup nitrates have gotten as high as 20ppm due to semi-cured LR and over feeding (my mastery of clown loaches didn't guarantee a perfect transition to a marine tank:)), but in the past month they have dropped from 10-15ppm to under 5ppm. Ph 8.2, sp 1.0225, temp 78-80,  DKH is 10, phosphates are unknown but I do know that my RO supplier has undetectable phosphates. <Well, I'm very glad to see the downward trend in nitrates. Sounds like you're getting a good handle on the husbandry associated with this tank! If you want to try to get more product out of the skimmer, you may need to adjust air or water flow. At the very least, if you're pulling some stinky junk out weekly, that certainly is better than nothing, particularly with improving nitrate levels. Just for the heck of it, you may still want to check those phosphates, just to see if they are indeed undetectable. Sometimes, commercial RO providers can be a bit lax in changing membranes, and detectable levels of phosphates, etc. are present in the product water.> Current setup is: 55g glass tank, Red Sea Berlin HOT skimmer with RIO 2500, Emperor 400 (until the refugium planned for early next year), and 2 Rio 600 powerheads for circulation. Lighting is a CSL hood with 2 65w actinics and 2 65w 8800K bulbs running a timed 12 hour cycle. Trying to build up my coralline algae, otherwise could possibly cut back on lighting time. I plan to move my skimmer to the sump when it is installed. Any pointers on enhancing with my current setup? current skimmer setup, old picture: Thanks again, Emo <Well, Emo, sounds like a nice setup there! One of the things that you may want to do is change and/or clean the filter pads as often as possible. Mechanical/chemical media like these can become nutrient traps if not maintained diligently. Also, have you investigated a deep sand bed? There is some compelling evidence that a 4"-5" sand bed can measurably reduce nitrate in closed systems. You'll really like the results the refugium will deliver, too! Keep up the good work! Good luck! Regards, Scott F.>

Club Urchin Spines Hello!     I enjoyed your dissertation on sea urchins on the web.  Thanks!       I have used up all my club-spined urchin spines by making them into jewelry, and selling them!  All I have left is a collection of spines that are .5 inches and down, nearly of no use in jewelry.  Can you tell me where to find more larger ones?  The ones I started with were up to 7 inches long...     Thanks ever so!     Jim

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