sea urchins ( good or bad?)

[helcat17]

ok i got a couple of new live rocks and noticed that i had a couple hitch hikers (2 small sea urchins ) i need to know if these are ok or do i need to try and get them out? if you absolutely need pics i can try and get a couple

[rayn]

They are a good part of a clean up crew. Some eat algea, be it HA or coralline. Any ideas what kind? Pincushion, long spine, pencil?

[cloak]

Here's a good article.

http://www.reefkeeping.com/issues/2003-11/rs/index.php

[Agu]

In general urchins are OK until they get big. Pincushions will pick up stuff including snails and frags to camouflage themselves. All urchins are like mini bulldozers when they get big knocking over stuff as the plow ahead.

Enjoy them now but realize you may have to get rid of them eventually.

[EdKruzel]

I like urchins in the tank. If your parameters are correct and calcium levels above 420, an urchin will help spread coralline algae very quickly. Urchins are quite ancient in design and not very evolved. Their mouth pieces are somewhat beak-like and cross over in a triangular pattern. This is good for cutting and scraping, however when scraping a hard calcareous algae, more of it breaks into tiny pieces and floats away then what gets devoured. Yes there will be a tiny white line across your rock, but again if your parameters are good, that will quickly grow back. The uneaten portions that floated away will spread and cover whatever it settles upon.

[x947]

do urchins climb the glass ? if so, do their strong crushing and chewing actions pose a risk to scratching acrylic aquariums ?

[kctango]

yes they do climb on glass, as for acrylic I dont as I have glass and have a urchin the size of a tennis ball crawling around but have never seen any damage on the glass. He is a bulldozer of sort but not as bad as my hermits.

[Tin_Whistler]

I really like Sea Urchin’s, but if possible epoxy your rocks together so it won’t knock them around.

Also, if it has sharp looking spines try not to touch it.

[stallione]

I was surprised to see mine on the glass the other morning, mine is getting very big. two years ago it was the size of a nickel now it is almost as big as a golf ball.

[snorvich]

I was surprised to see mine on the glass the other morning, mine is getting very big. two years ago it was the size of a nickel now it is almost as big as a golf ball.

And in the not too distant future, a softball.

[89Foxbody]

I have a pincushion and I like him/it. It's funny to see him carrying stuff around at times, though it can get aggravating when it knocks things over.

[EdKruzel]

Hopefully all with corals have them properly located and adhering to the rock. The answer to if they can damage acrylic is definitely YES... Acrylic is great for visibility, much clearer than glass, but also much easier to scratch.

[brycerb]

My long spine is almost a foot across. He is one of my favorites. My oldest son likes it when he poops out of the top of his "head".