Urchins

[hnf2k]

i was at my lfs and saw a sea urchin on the glass of one of their tanks. they said it will eat algae off the glass and rocks. but on swf.com it says they may eat corraline algae which im guessing is bad.
so now my question is. is it common that they eat corraline algae? and i know how snails and hermits may get eaten by a puffer, but will a puffer go after a sea urchin? and do those needles on them do any harm besides stick you? are they venemous? are urchins aggressive?

 

[carrie1429]

I used to have a purple spiny sea urchin, they are cool looking but mine always left a white spot where my purple coraline used to be, also once they get bigger they will topple over rocks witch is what mine did. He never harmed anything else besides me and he was a real pain to get out of my tank. They can stick to rock and glass very good and its not exactly easy trying to peel an urchin off the rock, and I couldn't just pick him up off the substrate because he never went on it. So I think in the long run they do more damage than they clean.

 

[katara]

After having my pencil urchin for @least 6 months and having noticed little-to-zero coralline destruction,I have recently purchase a spiny urchin and love the diversity they both give to my tank..They move sooo slowly that I really don't see them to be a significant threat to my coralline..HTH

 

[hnf2k]

i guess it helped. actually it complicated things more being that you 2 have the exact opposite stories. would a puffer or lionfish attack an urchin?

 

[nacl-h2o]

I don't think so, I know many triggers will eat them, if one is in your plans in the future.
As for algae, almost all urchins will eat coraline. Some prefer other algaes first if you have alot of other algae they like, but if the algae starts to get scarse they will turn to coraline if they're not eating it already. I have also noticed some are less like to eat it when their small and will start eating it when they get larger. Do not buy an urchin unless it's OK that it eats coraline.

 

[bang guy]

I have lot of the Diadema species of Urchin. They have medium long sharp spines. They are all venomous but most are an extremely mild venom. The physical size of the spines hurts more than the venom.
Mine all eat coralline. I believe that they actually propogate the coralline when they eat it though. When crunching it up most of the pieces fall out of their mouth and blow around the tank. They eat a LOT of green algae. If you have a shortage of Coralline go with a Tuxedo urchin.
They become bulldozers when they get larger. Any frag not glued will eventually be knocked down.
Diadema are herbivores.
Avoid the Pencil Urchins they are carnivores and will eat coral.
Guy

 

[clarkiiboi]

I had the pincushion urchins----coralline algea EATERS! Mine never went to the sand for the algea there, so back to the LFS and coralline is back in force. As for the spines, at my LFS 1 woman can get hit by the spines and be ok, the other woman has a very, very mild reaction to it. HTH

 

[striker]

I have had 2 long spined urchins for almost a year and they haven't caused any problems. They will eat coraline from time to time but as bang guy said earlier it actually propogates and spreads out the coraline. Diversity in a reef tank is important. I always hear about people getting rid of their hitchers just because they might be troublesome. Most of the time they aren't but are destroyed anyway. A lfs employee shocked me once when he told me that when urchins come on their lr orders he scrapes them off with a knife to kill them. His advise was to destroy mine immediately because they were terrors. His advise turned out to be a bunch of bull. Many reef inhabitants act differently even if they're from the same species. I'm not sure if a puffer can get to them. They are extremely hard to dislodge. Their spines will hurt but I doubt you'll be careless enough to get stuck.