Please visit our Sponsors

FAQs about Sea Urchins, Sand Dollar Behavior

Related Articles: Sea Urchins

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

Tripneustes gratilla in Hawai'i. Wish we were there right now? Me too!

Tuxedo Urchin Shrinking     12/6/13
Dear Crew,
I have had a Tuxedo Urchin for about 9 months - seemingly healthy and happy (I like to think). Today he is noticeably smaller. His spines are strait and healthy looking, he has his usual collection of stuff on his back, he is moving normally. But, he has shrunk by about 1/3 - he is a smaller "ball" than he was yesterday. A week ago I aqua-scaped and added some fish - tang, wrasse and a clam. Water parameters are all good - 0 nitrates, 440 Ca, 10KH, 7.8ph (night).  What gives?
<Echinoderms do shrink... under/given a lack of nutrition usually... Yours is likely starving... though, other influences can result... e.g. imbalances in aspects of water quality... I'd check you Mg conc., and do list the other livestock, live rock, mechanicals... when writing folks... as this may well provide useful clues. Bob Fenner>

Echinothrix calamari question, cause for concern?    3/4/13
               I am unsure if this was answered.  Can you please take a look and advise. 
Subject: Echinothrix calamari question, cause for concern?
               I love your work.  I always come across your information when doing research and find I am soon reading topics other than my current research criteria.  Your efforts to help people elevates the hobby to a new level of understanding and appreciation.   I have a question on one of my Urchins.  I have read your articles, searched the site and not found the information.  This does not mean that you have not covered it already but simply that I cannot locate it in your vast information repository.
Unfortunately this is because I am searching for Urchin and losing so my results are on spines falling off. 
<Mmm, trouble for sure>
               I have a Longspine Banded Urchin. Echinothrix calamari. Pictured below.
<I see the linked pic lifted from Live Aquaria; but can't unzip the other/s>
 An amazing species unlike any urchin I have seen.  He looks like a tuxedo that they gave long thick spines to, banded like a lion fish and a balloon butt that is not bright orange like other targets.  I have had him for about 2 years.  The reason I am writing is that I am noticing many spines are no longer banded and It seems to be growing.
<Mmm, well, the banding, and colors period are a matter/function of nutrition and local conditions over time>
 He does not lose spines and grow new ones back without bands. In fact he hardly ever lost spines unless bumped by me by mistake.  It is that the bands on spines are fading away.
           I suspect this is due to diet
<Likely... and/or aspects of water quality... but most all the latter can/will be made up by the former>
 and he is losing his venom or degree of potency.  While I would like to say it is because he is so happy and unthreatened that he is evolving to not need it we both know this is not the case.  I have Caulerpa fern and Red Halymenia in the DT along with Nori sheets and normal rock grazing.  I have 2 other urchins (tuxedo's) and all 3 seem to be doing great and had all for 1.5 years or more.  No signs of stress, sickness nor threat agents.  I appreciate any thoughts.  If it is diet I would like to know what sort of venomous food I can give him to allow him to keep his normal diet and coloration and best replicate the wild environment he is used too.
           Info that may help or be needed.  I have a 300g DT, 400-500 NWV if my QT tank is plumbed in for an isolation tank instead. I have 0 Amm, 0 Nitrates, 10 Nitrates, .36 Phos, 410 Calcium. 9 DKH.  76-77 degrees.
1.023-1.024. 8.2ph. (I have since added a Bio-DeNitrator in case my macro fails and my nitrates climb.)  I am running a reef tank, however I am heavy on the fish and slowly adding the coral.  I have 5 tangs, 5 clowns, 4 Anem, 1 Rusty Angel, 5 Fairy Wrasse and other assorted gobies.  Favites, Zoa, play, pearl bubble, frog spawn branching, and some Ricordea mushrooms. 
           If you need to know anything please let me know.
<All this looks fine to me... "Nothing jumps out" as being deleterious... Do you measure Mg concentration? How do you boost RedOx?>
Longspine Urchin, Banded
Does your reply come by Email?
<Yes; a direct reply from our mail webserver here. Bob Fenner>
Re: Echinothrix calamari question, cause for concern?   3/4/13

Thanks for the forward.
"Do you measure Mg concentration? How do you boost RedOx?"
I do not yet test Mg.
<Necessary... for reef systems, organisms>
 I don't have the means to measure RedOx and ORPs start making my eyes roll back.  I actually got a ozone generator in a box of junk supplies for $50 and started reading on it.  However since it is such a deep concept and O3 being so controversial I have not implemented it.
I do believe its probe would measure ORP.
<Yes; and do see WWM re>
Please share your thoughts regarding the above. However can you tell me if his diet would have been something toxic in nature that he then was able to use as some species pick up venom from anemones. 
<Not Echinoids>
Or do they normally eat something that provides a chemical that allows them to create their own toxic proteins? 
<... such synthesis is "allowed" through nutrition... But this genus is not toxic/venomous to any real extent>
Should I be concerned if I cannot replicate this diet and he loses these bands?
<I would not be concerned in any case. The loss of banding is not significant functionally. BobF>
Re: Echinothrix calamari question, cause for concern?   3/4/13

Thanks.  Will tell the wife I am under orders to buy more stuff to test for Mg. :)
What is WWM recommendations on O3?
<... posted on...>
And also what is WWM recommendation on vodka dosing? 
Are the gains worth anything measurable?
<This too>
Thanks Bob.  I appreciate it.  I feared that after the bands went so to may the health of the critter.  We like him a lot as he is so unusual but still so familiar.  You just don't see this type everyday but his care is the same as is his function.  He fits right in at our house.
<Heeee! Now I'm picturing your house being band-painted ala a Zebra.
Cheers, B>

Need help with my urchin!!!   10/29/11
Today we got a purple urchin,
<Mmm, a note. DO check to ensure this is actually a tropical species... Some folks sell coldwater animals...>
when we was putting it in the tank after climate him for 20 min.s. My bf put him in the back of the tank. So he try to move him, after a little while some RED-BROWN substance was coming out of the top of the urchin!!!!!
What was that?????
<Likely waste material... possibly reproductive. Not a worry>
Did he hurt him??? It was moving after that n was climbing on the glass but then went on the bottom and hasn't move, is night time I don't know if is cause it's night???? :-\ I'm so worried I fell in love with this urchin!
:-( I try looking for this answer everywhere and still no luck. PLEASE HELP!!!
<Bob Fenner>

Urchin Breaking Spines -- 3/9/11
<Hi Ken, Lynn here today.>
I have a Longspine Urchin, Black (Diadema setosum) that has been doing well for several years in my 65gal. Its body is approx 2" in diameter and had spines 6-8" long.
<Wow, if I'm interpreting that correctly, that's an overall size of around 14-18' (36-46cm) across. That's a huge critter in a 65 gallon tank!>
Everything in the tank is healthy and no abnormal water tests. Last week in an attempt to catch a yellow tang, I baited a jar and placed it in the tank overnight. I have done this in the past to get the fish familiar to the jar and willing to enter it to get food. Has worked well.
<Heeee! That's a whole lot easier than chasing a fish around the tank or having to rearrange your rockwork!>
The following morning I noticed an amount of spines in the vicinity of the jar and assumed the urchin had entered the jar and broke some of its spines.
<That would be my guess as well.>
Through the following days the urchin has had all of its spines break at approx 2" in length.
<Was the jar in there over the course of those days as well?>
The spines are not falling out and there are no wounds or damage to the body of the urchin.
<Good. Dropping/losing spines is a very bad sign.>
They just seem to have broken.
Every single spine has broken to the 2" length. Other than that I see no abnormal activity as far as eating, color, moving and such. What do you think?
<I think you had a hungry urchin trying to get to the food/bait in that jar! You might want to leave some bits out for him at night and let him graze in the open. The good news is that with the shorter spines, he'll have a lot more 'elbow' room than before!>
Ken Grover
<Take care, Lynn Z>
Re: Urchin Breaking Spines -- 3/9/11

<Hi Ken!>
The jar was removed the following day however the spikes continued to shed several days later. Could the spines have been damaged and took some days to finally break?
<That would be my guess.>
I know it was a giant for that tank but it wasn't always that big.
<Believe me, I understand. I received several of these urchins as tiny hitchhikers years ago and was surprised how quickly they grew.>
I have a new 120 that I am getting ready.
I am sure everyone will be happy with the new space.
Ken Grover
<Take care, Lynn Z>

cushion sea star... beh...  7/13/10
I found a cushion sea star (perhaps 10" in diameter) floating in "Lake Boca" (which is south east florida, a man made lake, right off the ocean, that connects ocean to the intracoastal)
Anyway, it was floating, kind of on its side.
<Floating? Gone>
It wouldn't go to the bottom. It also floated upside down for a long time.
Nothing on the underneath side of it was moving, and there were no bubbles coming from the underneath.
It wasn't moving.
I thought it was dead, but, I definitely kind of felt a "thumping" or a vibration coming from it...
<Parasympathetic on your part... or something living in the test>
I watched it for a few hours.
Nothing changed.
Was it dead?
Or just doing its natural thing???
I left it in the water, because of the thumping that I felt, and I didn't want to kill it.
But, if it was dead or dying, I really wanted to keep it.
Someone ended up stealing it from me, anyway...
But, I was just curious about what was going on with it.
I've never seen any other ones in our lake.
<Someone dropped it in there... you can/could leave the (stinky) test (the external skeleton) out in the open for a few weeks... brush off the spines.>
I think I've seen similar ones in the Bahamas, but they are always on the bottom.
Never just floating on the surface.
Thank you,
<Welcome Carolyn. Bob Fenner> 

Pencil urchin on top of my emerald crab 5/8/2009
Is it possible that a pencil urchin would eat an emerald crab? The urchin is still alive however the crab is not moving. Please help.
<It's unlikely any sea urchin would catch and eat a healthy crab. But sea urchins are certainly opportunistic feeders, and a moribund or read crab might well be consumed. Crab moults might also be eaten, so check that isn't the case here. Cheers, Neale.>

Urchin Sex? - 05/14/08 Hi! <Hello!>> Researched through Google, found your site. <<Welcome>> Scrolled through for an answer prior to bugging you! (sorry!). <<No worries>> Our urchin is excreting a white string of material (think of like a frog laying a chain of eggs...). <<Ah yes…gametes likely>> The closest I found on Google was emission of sperm but no pictures to verify. Closest I found on your site was the article/question titled: Urchin blowing chunks. I've sent along a picture. <<Mmm, yes…does look like a sexual event (perhaps triggered by a change in water temperature and/or salinity)…and some chow for some of your tank denizens as well>> This went on for about an hour. When it finally stopped immediately did a 25% water change and checked levels throughout the night as well as kept vigil for any signs of change or distress. <<Depending on the size of the tank this may not have been necessary…but didn't hurt either>> Thanks for your help! <<Mmm…such as it was! [grin]>> This happened about 3 weeks ago, everything still thriving as though nothing happened. <<Indeed…nothing to be concerned about re this "event." Cheers, EricR>>
Tuxedo Urchin (Mespilia globulus) spewing black substance 03/18/08
Greetings all, I have a blue tuxedo pincushion urchin that released a black substance into the tank over several minutes. Everything that I've found about urchins in regards to spawning reports that the urchin sperm is white, and urchin roe is orange. Unless I've missed it, does the color of sperm matter? This was black. <strange> I got video of the end of the event as it was happening in my tank. It went on for several minutes and I got the ending of it. The video is at this link (public): http://www.viddler.com/YayHeaven/videos/20/ <nice video> I changed 3 gallons out of the canister filter carriage at 12pm. Spawning event occurred at 3pm. Amm0 Nit0 N'ate20 pH 8.4 SG 1.022, Temp 76.5 I know they do their spawning thing after water changes sometimes, but I'm wondering if this was even a spawning thing at all. First time I've seen my urchin do this. It's running around in the tank looking perfectly healthy and behaving normally. <Well, it certainly looks and sounds like spawning, but the color is strange... almost looks like bile. Maybe it had an unusual diet before you got it?> Your thoughts? Thank you! H.C. Anaheim, CA USA <Best, Sara M.>

RE: Tuxedo Urchin (Mespilia globulus) spewing black substance -05/07/08
Hi Sara and Crew, <Hi> I would like to write a follow up regarding my initial inquiry about my Tuxedo Urchin, posted on your website on this page: http://www.wetwebmedia.com/urchinbehfaqs.htm  Since writing you in mid-March, I have not witnessed the same occurrence from the urchin again. From the day it happened to present, the urchin continues to roam the tank looking as healthy as ever. It appears to be eating and excreting as expected. <cool> I acquired the urchin on the 5th of January 2008 and it has always been in the same tank that it released the black substance into 60+ days later. As for the animal's diet, my thoughts are that the amount of time the urchin has been in captivity wouldn't be relevant in this case, would it? <I don't know, it might be. Some animals take several months to truly "settle in."> I'm thinking not, but anything is possible. If there is any instance that you know of where an urchin would release bile without any obvious stressors in the chemistry of the water or because of fellow tankmates, or if you have other ideas about what the substance might have been, I am still very curious to know. <I'm curious too. I asked one of my friends who is a marine biologist. I showed him your video and he thinks it was either spawning or some kind of diarrhea. However, he had no information as to when, or why an urchin might have diarrhea. Whatever this was, it may or may not have been stress related. I'm sorry, but I don't think we'll ever know for sure exactly what this was or why it happened. If it happens again, try to collect a sample and take a look under a microscope. :-)> Thank you for all of the work you do, and have a pleasant week! <Thanks for the update!> H.C. Anaheim, CA USA <Best, Sara M.>

Pincushion Urchins, Spine Dropping 9/5/07 Hi. <Hello> I have two pincushion urchins in my 55 gallon tank. I have had them about 5 months and they have been doing very well. However, following our last water change they began to lose spikes. I think it is because of summer, it got hot in the room where the tank is and the temperature went from 78 degrees to 84 degrees in less than a day, when I wasn't home. <Most likely the cause, they are very sensitive to environmental changes.> I of course made sure the water was the same temperature at the time of the water change as what was in the tank (it was 78 at that point) and the salinity is fine. All other water tests are fine as well. I know that losing their spikes probably means they are going to die, but I am wondering if anything can be done for them. <Provide good water quality, stability is about all.> I am currently treating some new fish in my quarantine tank so I can't move them to that tank. <Moving them now would probably do more harm than good.> Also I have a maroon clownfish I got at the same time and he has been burrowing in the sand for the past 2 weeks. He doesn't appear to have white spot or velvet and neither does the other fish in the tank, a lawnmower blenny. He still eats very well and seems to be doing fine otherwise. Is there something wrong? <Clowns dig, Maroons more than most, is a natural behavior.> Thank you for all of your help. It is appreciated! <Welcome> <Chris>

Black long-spined urchin. Urchin Dropping Spines 7/12/07 Hi, my name is Angie. <Hello> We have owned Fresh and Brackish tanks for many years but recently had to give them away as we moved out of state and could not guarantee their safe travel. <Tough to move tanks, especially over any great distance.> We are now settled again and began a Salt tank. After about 4 weeks we got a Black long-spined urchin. <Probably too soon, they are very sensitive to water quality/changes. Also, there are many urchins that go by this name, see if you can determine the species so that it does not outgrow your tank.> The dilemma is that after we had him about one week he began dropping spines and literally has about 7 larger ones left and a few lil ones that are new. (This has been going on for almost two weeks now). We don't have much in the tank with him. We have an 80gal tank. About 20lbs of live rock which has begun turning pink on one whole side and has some green spots. <This is probably not enough to sustain him long term, think about adding close to 50lbs. for both the tank and urchin's health.> About 20 lbs of live sand and we also have a very archaic cleaning crew of snails and crabs. There are no fish in the tank with him yet. The brine shrimp we have been feeding him are the frozen cubes. <Switch to something better than brine, is the potato chip of the sea. Mysis is much better.> Our LFS told us that feeding him Algae tabs (like you would use for Plecos) would be fine and I was also going to get him some dried krill. <Will help.> He is still very mobile but drops spines constantly. We have tested our water several times and also had the fish store test it to be sure and ALL the levels are fine. <What is fine, numbers please.> They aren't sure why he is dropping spines, but they know it can't be good. About two days before he began dropping his spines we noticed some spots on the glass that we found out were hydroid jellyfish. We have been told repeatedly that although no one knows why 'Spike' is losing spines, it isn't because of the hydroids. <Unlikely.> The hydroids are pretty much gone now, and Spike is still losing spines. One actually broke off while he was eating some dried seaweed and he began eating the spine! I have looked at him very closely and I don't see anything on him, like a bug or parasite. If you have any suggestions we would so greatly appreciate them. We just don't know what to do with the lil guy and we really don't want to lose him. Thank you so much for any help you can give! Angie <Losing spines is never a good thing, usually caused by stress or illness. Double check your water parameters, and make sure your pH and SG are stable, small swings in these can negatively effect the urchin greatly. Otherwise take a look at our urchin FAQs and see what applies. http://www.wetwebmedia.com/urchinfa.htm .> <Chris>

Urchin Poo?   4/9/07 Happy Easter to all my fish professional friends!   <Thanks and to you as well.> I have a question  and have been searching the site for a couple days now but I'm not finding an answer.  This is probably really stupid, but I need to know!  I have a  black long-spined urchin.  I have noticed that it drops brown pellet like  things out of the "eye" on top. <Well it's actually an anus.....and right there I think we've answered your question but lets continue.......>   I have been looking through my fish books  and they don't cover urchins well so I'm hoping you have an answer.   They're tiny little round pellets, he will drop quite a few in rapid  succession.  My kids all think it's urchin poo, I'm inclined to agree,  what's your take?   <Poo it is my friend.> Thanks so much for your time.   <Anytime.> Warm Wishes, <To you as well.> Amy <Adam J.>

Skimmer Production/Urchin Behavior - 11/27/06 Hello everyone, <<Howdy>> I have a 100 gal reef tank that's been up and running for 6 months now. <<Neat>> All the parameters are looking pretty good: sg-1.024, pH-8.4, KH-11, cal-440, ammonia & nitrate -0.  I run the tank at approx 80 deg +- 1.5 deg.  I just recently put in an automatic water leveling system which has kept the sump level constant. <<Excellent> That helped me get a little better production out of my LifeReef venturi 22-1/2" tall compact skimmer.  There is no adjustment on the venturi and a gate valve adjusts the output of the skimmer. <<Mmm...you could utilize a "pinch-clamp" on the venturi tubing to make adjustments re>> A Mag 9.5 pump supplies water to the skimmer.  However I still only get a cup of dark skimmate per week.  Is there anything else I can do to improve the output? <<This may be just fine if you have a light bioload/don't overfeed/have other mechanisms for export.  If this isn't the case, then I suggest an upgrade to an AquaC or Euro-Reef skimmer>> All the inhabitants are doing fine, there is 1 yellow tang, 1 ember blenny<<...?>>, 2 Banggai cardinals, 1 Mespilia globulus, and a number of different corals.  I have about 200 lbs of rock that the urchin lives in. <<A lot of rock...>> The other day I noticed a white creamy substance coming out of some slits on the top of the urchin, I'm assuming these are gills? <<Hmm...I don't believe so, no>> Do you have any ideas what this was? <<Likely gametes, a product of sexual reproduction...I observe this with my urchins from time to time>> Also there are not a whole lot of green algae for it to dine on and I was wondering if maybe I should sell it back to the LFS?  Don't want it to die behind the rocks somewhere and poison the tank. <<In my experience these critters seem to show a preference for coralline algae, but you might try some Nori from the local grocery or some of the "sheet" algae provided by Julian Sprung's company 'Two Little Fishies'>> As always I really enjoy WWM and the crew and thanks in advance. <<Welcome...as always.  EricR>>

Echinothrix calamaris (Hatpin Urchin)    1/19/06 Hello Bob, <James today>    I work at a small LFS and we the boss picked up 3 "zebra urchins" at our supplier the other day. They are Echinothrix calamaris I believe. My first question is, do these urchins have the ability to "shoot" their shorter spines out? <<No... don't shoot out. RMF>> I touched the longer tubular spines with my thumb while trying to move it (and ONLY the bigger ones, I am positive) but received two of the smaller spines buried in my thumb. Very painful. I've heard from several sources that they may be able to do so but no definitive proof. Second question is, are they reef-safe? They are in our fish-only tanks at the moment because we could not find any information on whether they are or not reef-friendly. <The spines of these urchins have hundreds of alternating light/dark bands, some being strong, thick and hollow and others shorter and finer with all being very sharp.  I'm guessing while you were trying to move it the shorter finer ones nailed you.  The venom is very much like a bee sting so it doesn't surprise me that it is painful.  Interesting urchin as in nature they can attain lengths of up to 9" and  Banggai Cardinals often seek shelter among their spines during the day.  I did some researching and couldn't find anything as to the urchin "shooting spines".  James (Salty Dog)> Thank you and keep up the good work! <You're welcome> Brandon

Urchin Sperm? Good afternoon to all the crew! <Good afternoon, Mike G here> Your site is simply great! I find all the answers to any possible questions I have, except for this one. I've been looking through your info section and your FAQs, but I didn't find anything. <I have just started out here at WWM, and I agree with you 100%.> A few days ago, I was cleaning my tank and my hand hit my long spine urchin (blue spotted I think... not quite sure about the specific kind of black long spined urchin). After a few swearings (... being stung by an urchin hurts....!), the longspine expelled some kind of white cloud. A few seconds later, he did it again. It was the first time I see it doing such a thing. After that incident, everything in the tank seemed under control and pretty much normal. The white clouds dissolved in the water... Is it sperm (Maybe I excited it?! ;)) or a defense mechanism. <I would say it was an Urchin spawning. Check the following link for more information, namely the second to last topic: http://www.wetwebmedia.com/urchinreprofaqs.htm > In the second case, could it be harmful? <I personally doubt it would be, but do not hesitate to do a water change should your livestock begin to show adverse reactions.> Thank you very much!! And again, great site!! <Glad I could be of assistance> Ivan p.s.: I'll probably get rid of the urchin in a few days (trade it for a tuxedo at my LFS) because of my Xenia and LPS corals

Urchin Question My urchin is pretty big he's some LFS purple urchin and we've had him for about 11 months and we just placed him in a smaller rockier tank because of the new addition of a snowflake eel both tanks are regularly tested and cleaned but I'm not sure if it is because its difficult for him to get around (his spike make him the diameter of a soft ball) or what he's starting to lose well the lots about 15% of his spines at the top of him self are kind of making him look like he rubbed to close to the rock and couldn't weave threw but I'm still worried any suggestions would help thanks <I got to tell you my pincushion urchin is a pig and continues to go into places he shouldn't go and breaks his spikes all the time.  This is quite common for mine. I am guessing yours is doing the same thing. MacL>

Urchin eggs? <Hi! MikeD here> my urchin which I was told to be a purple urchin is actually brown with purple tips on his spines well anyway he put out say.... 20 yellow tiny eggs it seems to be. it just sits in a hole in the rock which I assume is natural behavior?<While eggs are a possibility, I suspect you've just noticed your urchin having a bowel movement, and don't feel dumb about it, as it's an honest mistake, with most people never considering an animal that eats with its butt and that poops out of its head! Urchins are actually a source of the oceans sand as extra calcium and silica gleaned from the algae is excreted through a small hole on the very top>.he lost 2 spines because my damsel fanned him, but I don't know what the yellow balls are. Thanks for your time<Not a problem, as time is the one thing I have plenty of. You might want to keep an eye out for additional needle drop, as urchins such as yours require good water quality, and shedding being a prime indicator that parameters are dropping. Before the availability of modern dependable test kits, urchins were often used as "miner's canaries" to monitor water conditions> , Aaron

Urchin Question Howdy, Crew! <Cathy> I have a question that I can't find the answer for, and hope you can help. I have a spiny urchin, possibly a Diadema savignyi - well, it's a Diadema, anyway. Which of the three is hard to say. My question is - this guy eats a lot of green coralline. (Fine with me, I'd rather have purple.) However, now HE is turning green! The spines are changing color from the body upwards. When the spines started being striped in color, I wasn't too concerned. But now his 3" spikes are definitely green, for at least 1/2" or so, though the rest of the spikes are each purple. The tiny blue spikes near his body are just fine. He seems fine, too, but is this color change normal? Anyone ever seen a GREEN purple spiked urchin? <Yes. Urchin coloration is something that not much is known about, much debate has occurred over UV blocking pigmentation, attaching shells as an apparent radiation shield, and color changes during maturation (most likely what you are seeing). I wouldn't be too worried> BTW, his name is Get The Point. :-) THANK YOU! -Cathy <>< Fort Worth, TX <Best, Chris>

Urchins destroying reef Hallo! <And you Glen> I'm living in Papua New Guinea. I'm about to be spending a lot of time in and around the water diving and catching fish for export. I want to gain some tools and advanced knowledge in reef stewardship. I have moved to an area right on the water where there was dynamite used to build a wharf and also to kill fish. So there is plenty of work to be done to help the area recover. <Yes, well put.> My biggest concern I have noticed is the incredible abundance of black long spined sea urchins, who seem to be attacking the rejuvenating reef with ferocity - and seem to be winning.. <Only seem to be... these are likely Diadema savignyi... and their population will abate once the blasting, construction are over... there are natural mechanisms that will come into play to delimit their numbers... have experienced this first hand in Mabul and Kapalai, Malaysia> I want to eradicate these pests along with the crown of thorns and help educate the people about the importance of the reef and rejuvenating it to the abundant resource it once was. Are these urchins exportable? <Not really... are sometimes traded as ornamentals as very small (less than palm size overall) individuals... if you're going to destroy these and Acanthaster, #1 BE CAREFUL! Very sharp (and toxic) animals... secondly, you'll need to develop and implement a scheme to bring them ashore and let them dry out in the sun (don't just smash them on the reef... this will likely just speed up their distribution> I have been killing a few underwater by smashing their shells, and then fish come in and eat the insides. Does this cause any further problems?? <Yes... can greatly increase their numbers through aiding reproduction> Can you suggest any good reef organizations that may be able to help with educational materials? <There is a huge amount of older data on the Crown of Thorns, some on urchin removal... that you could reference through libraries, many "pro-reef" organizations... but I assure you, better (really) to ignore them... they will die back in due course and provide valuable service in the meanwhile. Better to focus on the "human" "software" issues... perhaps getting folks to place rubble, rock around where the wharf is being created, develop permanent moorings... for dive, anchoring purposes...> Thanks for any help you may be able to give Glen Butler <Good luck, life to you my friend. Bob Fenner>
Re: Urchins destroying reef
Thanks for the tips Bob! Its hard to watch the reef being attacked like this though.. <I understand... but believe that most such "population explosions" are the direct result of the disruption... and are more "solved" by the urchins than other ways... patience my friend. Count and perhaps weigh some sample animals, record, plot their abundance, density... in a few years you'll find they're about the same as most every other similar micro-habitat (with consideration to the ongoing human-effects of the wharf/use> Further away from the wharf there are much less urchin activities, I'm just a little worried that they might bloom even more and destroy even  more of the reef. <Other animals (e.g. triggers) will mediate their numbers... as will parasite fauna... you will see> The traditional owners of the reef have put a ban on fishing in the area close to the wharf because they want to regenerate the reef, but these invaders seem to be doing much more damage than any fisherman.. I guess ill look at getting them out of the water into the sun. Thanks Bob Glen <You are welcome my friend. As stated, I would take this opportunity to gather data... and perhaps publish it. Bob Fenner>
Re: Urchins destroying reef
Thanks again Bob,,, I'll do my best and take notes of the eventual outcome.. Glen <Would appreciate seeing your input as time goes by. Bob Fenner>

Sea urchin erupting?...sort of! Hello Bob, <Anthony Calfo in your service> We have what I believe is called a Diadema savignyi sea urchin.  <AKA Blue Dot long spine sea urchin> It is black and you can see bright blue in it's body at night. anyway...last night he seemed to have some kind of volcanic eruption. All of a sudden about a million (ok that might be a little exaggerated) tiny white pebble like things rushed straight up and out of his head (or top of him). At first I thought it might be some kinds of eggs but it really looked like tiny bits of rock. and the worms who caught the pieces quickly spit them out with no interest at all. What exactly was that and will he do it often?  <excrement...and yes, as often as necessary> Is he special, should I send him to David letterman? <possibly... I have yet to see a powerful, pooping prickly sea urchin on his show just yet> Christina <thank you for the smile... I think I learned this tidbit the same way more than a few years ago. kind regards, Anthony> ps: you usually get much more educated questions from my husband Pat. I really had no interest in this whole fish tank thing until one day I went to a very nice Aquarium and came home with our first creature...a little blue leg hermit. I then realized that sea creatures were extremely interesting and entertaining. (and my husband is learning that they are very essential to any tank) so.. now we are in the process of setting up a reef tank so I can have zillions of creatures! I was starting to throw my husbands tank all out of whack.

Tuxedo urchin I got a blue tuxedo urchin (Mespilia globulus) yesterday. About ten minutes after being in the tank, it made a beeline for the front glass, and crawled up it. It won't come down from the glass, it slowly works its way around the tank, and right now its on the side of the powerhead. Is there any way to entice/goad it down? <yep...Jack Daniels and cigarettes... Thanks for asking> <PS... they often explore their surroundings for the first days/weeks...patience my friend. Anthony>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: