Sea Urchin

[Ne0eN]

This guy was originally a hitchiker on some LR. Year and a half later he's about 2.5-3 inches across. Should I keep him? Is he reef safe? I read somewhere that they can erode LR.

 

 

[lmeyer]

Don't know about this particular one, to me it looks most like Echinometra mathaei (http://wetwebmedia.com/urchinsii.htm). I have two pencil urchins in my reef for turf algae control. I have two problems with them, first you can tell exactly where they have been by the bare patches on the rock (they even eat the coralline) and second, they do knock stuff over. I've read that the long spine urchins can also scratch acrylic and puncture fleshy coral polyps. I guess that when they are clearing the rock they do "erode" it a little, but I doubt it is significant enough a reason to pull them. On the other issues, though, thats a personal choice.

[rocko918]

I have heard of people putting them in their fuge.

[mogurnda]

I vote "friend" with reservations. I have two that are probably rock-boring urchins, one that came with some TBS rock, another from Garrett.

 

Positive:

The areas they graze are completely scoured of hair algae.

I haven't seen any bulldozing, but my corals are epoxied in place.

 

Negative:

As noted, they remove coralline. In my 90, it grows back fast.

 

If it's a tank with enough room to graze, I'd keep it.

[Lee Stearns]

I have two that I rotate around from one tank to the fuge to the main tank and back- they are heavy grazers- and can clean an area of coraline algae as well.