Urchins

[Donya]

I've been reading about sea urchins lately as a passing interest, but there are some things I've been trying to look up and havn't found conclusive answers for:

- how well do urchins handle air exposure? I know it can be a problem for starfish but I can't find any references to short-term air exposure adversely affecting sea urchins.

- when sources refer to omnivorous urchin species, what exactly does that include diet-wise? I read the species index post on longspine urchins mentioning the riccordea munching tendency. Is taking bites out of other softies common in any urchin species?

I'm also wondering why they seem so unpopular...some of the urchins in the LFS sit around for months. Other than carnivorous/toxic issues with some species, is there some less-than-obvious problem/danger with urchins?

 

[Opcn]

Urchins need alot of room to look normal, keep that in mind.

 

[SkiFletch]

Biggest issue with urchins IMO is their uncanny ability at bulldozing rock stacks. Dunno about exposing them to air though...

 

[Donya]

How do you mean "look normal"...avoiding spine breakage/loss? I read that the shorter-spined species like to cram into little spaces and move rocks around though. I can see where crowding and space would make a longspine urchin look ratty, but I'm confused about the others.

Biggest issue with urchins IMO is their uncanny ability at bulldozing rock stacks. Dunno about exposing them to air though...

Doh! This appeared while I was typing lol. Some turbos do a number on rock piles too though and that doesn't seem to deter many people

 

[Pheonix]

i kept a black long spined sea urchin for well over a year in my previous tank it did eat some rock but it never moved a thing about and generally was a very good tank mate, it was a serious algea monster

the only reason i had to give it back to the lfs was i was moving house quite far away and i just couldnt risk him in the move, i sure will be getting another one for my new tank in the near future

dont know about the air thing never had mine out of the water but i wouldnt risk it to be honest

 

[Fatty]

i kept a black long spined sea urchin for well over a year in my previous tank it did eat some rock but it never moved a thing about and generally was a very good tank mate, it was a serious algea monster

the only reason i had to give it back to the lfs was i was moving house quite far away and i just couldnt risk him in the move, i sure will be getting another one for my new tank in the near future

dont know about the air thing never had mine out of the water but i wouldnt risk it to be honest

My Mine Urchin, has no problem handled out of the water (putting in to the tank like 5-10 seconds), it does very well cleaning up the rocks, it has pushed a few rocks around but nothing major.

 

[Donya]

My Mine Urchin, has no problem handled out of the water (putting in to the tank like 5-10 seconds), it does very well cleaning up the rocks, it has pushed a few rocks around but nothing major.

Are mine urchins in the same genus as pencil spine urchins? I have read a lot of conflicting info about that genus as far as what the species eat and their behavior. Do you have yours in with any corals?

 

[Fatty]

Are mine urchins in the same genus as pencil spine urchins? I have read a lot of conflicting info about that genus as far as what the species eat and their behavior. Do you have yours in with any corals?

Yeh, tho I only have pulsing xenia and some button polyps, the urchin seems to avoid them.

There is another urchin called red slate pencil urchin Heterocentrotus mammillatus, which is different to the pencil urchin/ mine urchin/ club urchin which are Eucidaris tribuloides, which is what I have.

I have read bad things about the slate red pencil urchin, but in that same book they don't comment on the mine urchin

I have had the mine urchin for a year now, and he is no trouble and great on any hair algae


Mine Urchin

 

[Donya]

There is another urchin called red slate pencil urchin Heterocentrotus mammillatus, which is different to the pencil urchin/ mine urchin/ club urchin which are Eucidaris tribuloides, which is what I have.

Aaah...this makes sense now. It looks like some of the sites I was looking at had the species misidentified (or used the wrong picture). Thanks for the picture link!

 

[flamingonhot]

Air exposure, I can see why they would think it could harm them, but IMHO it doesn't do much.


If you ask me why they aren't the greatest thing and why people don't buy them, they strip your live rock clean. Eating hair algae is an advantage, but mine decimates the coralline algae even. I end up with white live rock. Also, they have a tendency to kill soft corals, not by eating them, but by poking into them with their spines. I had xenia on the bottom of the tank, and the urchin went over and just practically swatted half of them to death.

That what i've seen in my limited experience with them.

 

[Donya]

If you ask me why they aren't the greatest thing and why people don't buy them, they strip your live rock clean.

Hmm...I have one snail that does that. Very interesting. Would that affect the LR's filtration efficiency? Just thinking of the removal of algae as a nitrate reducer.

I had xenia on the bottom of the tank, and the urchin went over and just practically swatted half of them to death.

Ouch do hard corals just retreat when an urchin comes past? Seems like some of the big puffy LPS species would be urchin-incompatable if softies have that problem.

 

[Donya]

You know you've become addicted to marine and read far too much on strange topics when cartoons start popping into your head involving invertebrates. After seeing how mine and pencil urchins wiggle around when walking and being picked up, I couldn't resist doing this:

A deadly ninja urchin encounters an unsuspecting starfish: http/img.photobucket.com/albums/v281/kwippo/urchin1s.jpg
(linking because it's a big-ish picture)

I would appologise in advance for the uncalled-for episode of echinoderm humor but I'm still cracking up at the spine wiggling I saw Ok back to being serious

 

[dixaisy930]

Just thought I'd throw in my personal experience with my pinscushion urchin (which is my mother's favorite critter in my entire tank-she always asks about "Urchy")

I haven't noticed mine to put any kind of dent in my coraline algae. My rocks never look stripped. It did, however, "trample" my xenia. My star polyps have done alright though. It did pick up my feather duster, though, and I believe that's what killed my feather duster. I'm guessing a spike pierced the duster.

 

[ostrow]

Pencil urchins aren't a great idea. They will eat some corals or disturb them enough to cause problems.

I had a longspine that was fine, never toppled anything.

I much prefer the pincushion urchins though as long as your corals are secure in the rocks. They are cool, kids like how they capture "toys" and carry them around.

 

[bitfishy]

I love my urchin - he's very similar to a purple sea urchin, but he's pink. There's the comedy value of course when he picks up a very alarmed and disgruntled hermit crab and wanders around with him all day, and they do eat the algae. He eats corraline, but that grows back and I was told once that their 'poop' helps spread the coralline about a bit - I don't know if its him but mine is certainly spreading. They do tumble rocks more than turbo snails but I've been lucky in that it hasn't caused any harm and I've just expoy-ed the vulnerable ones as and when its happened.

IMO they're a great addition to a tank.