will an urchin grow more spines??? Please help!!

[mrstwig]

:help: My sea urchin has been losing his spines daily now since I added a coral banded shrimp and a sand sifting seastar. I just talked to the lfs and they are going to take them back. I have no concrete proof that they are the cause of the urchins loosing his spines but I believe that somehow this is the problem. It was suggested that possibly my water perimeters were out of wack but they are great and everything looks very healthy and well in the tank. I don't know much about the urchin (a pencil perhaps??) but his color looks good, kind of a dark maroon with dark tan spikes. My question is- can he regrow his spikes or is he destined to die?? If he cannot survive this, I would like to do something about it before he poisons the tank. He moves around as he always has, he just has probably 20-25% less spikes than he should. Please help!!

 

[ophiura]

It is really important to know your SPECIFIC water parameters. Sometimes "great" parameters for fish are FATAL for other animals.
How long have you had the urchin? What are the specific parameters, especially specific gravity, pH, alkalinity and calcium?
The urchin can regrow the spines if otherwise healthy and tank parameters are good.
Your sand sifter star certainly has nothing to do with it, however, I strongly suggest it be returned if you have less than about a 100g tank with little live rock. Most, unfortunately, will starve to death in smaller tanks.

 

[mrstwig]

Thanks for the input ophiura, I was hoping to get some advice from you!
My water readings today are:
pH 8.4
ammonia 0
nitrate 10
nitrite 0
spec gravity 1.022
calcium 420
The urchin was with the tank when I bought it approx two weeks ago and I believe she had him for months. I bought a set up that was 8 months old and moved everything and put it back together-urchin, LR, LR, 2"hippo tang and a handful of snails. Water has stayed stable and I did my first water change a few days ago.
It makes me sick about the urchin. He's such a trooper, just does his thing with his "bad hair day" thing going on.......
I want a seastar or serpent of some kind so what might you recommend for my 29 gallon reef tank?
I really appreciate your advice ophiura!

 

[mrstwig]

I forgot to add that I called up my lfs and explained what I had learned about the sand sifting star and they are taking it back. I cannot condone keeping something that will starve in my tank. I wish I'd known.............

 

[ophiura]

IMO, your specific gravity is potentially fatally low for echinoderms like the urchin. How are you measuring that - refractometer or hydrometer? I would slowly bring it up to 1.025-1.026 (best checked with a refractometer). It is important not to do this rapidly. A nice slow way is to top off with saltwater instead of fresh for awhile, until it is in the new range.
But you are definitely at the very lowest I would go with an urchin...and it is possibly it is lower than that (or maybe higher). But that is what jumps out. Do you have an alkalinity reading?
Good news on the sand sifter star.
Serpent/brittlestars would be suitable for the tank once it is stable. Avoid the green brittlestar, a known predator. Any brittle/serpent has the potential, IMO, to be predatory and all should be spot fed. I have lots and have never experienced this but each tank differs. The only seastar suitable are non-reef safe stars such as chocolate chips, red generals, etc. No Linckia or Fromia, regardless of small size, is really suitable...most will starve without lots and lots of LR. The non-reef stars, however, will eat snails, clams, scallops, etc. So they may not be very welcome.