Urchin Problems?

Well we have 2 "black spiny urchins" as the LFS called them. I'm sure there's a more official name out there for them, but I haven't found anything. They're inner urchin-ness is about the size of a golf ball, with the spines forming about a 3" diameter ball to give you an idea. And they're, well, black. All over.

We've had them for several months now. Quite a while actually. And just recently "patches" have appeared on their bodies. Yes, not one urchin individually, but both. Also, both have had spines fall out for several days now. I know it's normal for an urchin to lose a few spines every now and then, but this is much bigger. We're finding spines (not broken off, but full spines) everywhere in the tank. The patches on them are areas without their little urchin skin. The black skin stuff is gone in those areas. Both patches cover about the area of a penny, but are steadily growing.

Both urchins still respond to being touched, how they're supposed to respond. Both are still scooting around eating. But both have patches forming and are both losing spines. If all of this was happening to just one urchin, I'd figure it was old age and the thing was dying. My concern comes from that fact that it's happening to BOTH urchins, at the same time. Although both urchins are from the same place, are probably from the same mama, and both have been with us an exactly equal amount of time. But they still shouldn't be dying at the same time, right? Is this an urchin disease or something? Everything else in the tank is just fine and dandy. The tank is 1.75 years old. We did recently add to our CUC, we added more emerald crabs and we added a crab we've never had before, red leg hermits. And these are pretty big hermits for a 46, they sure aren't the cute little blue legs we have. So I was thinking maybe the new hermits have been picking at the urchins. But then common sense catches up with me, and I realize that urchins have spines to prevent that sort of thing. There's no way those tiny crab claws could squeeze in to pinch anything.

Does anyone have an explanation for this? I'll try to get a good picture of the patches forming. I may even get my mom to use her super awesome macro skills to get a high resolution close up to help. These pics won't be here until tomorrow though, but I decided to post this today to see if anyone could help without pics.

 

Maybe you got unlucky and had that urchin disease from the Gulf strike your tank.

 

Urchins are very sensitive to water parameters, including salinity, and especially nitrates. I've heard of their spines falling off because of poor water. What are your params? Do you have a lot of algae?

 

Salinity, pH and alkalinity fluctuations are usually the problem. Make sure they have algae to eat.

 

you have 2 good sized urchins in a 46 gallon. I bet food is an issue. In the past my urchin lost spines for two reasons: Fighting with an emerald crab, and fighting with a linkia starfish.

 

We have almost no algae in the tank, although I know there is enough in there for them to eat. Maybe not on the rocks anymore, which is where they hang out, but if they really wanted to hunt for food, our back glass pane has enough coralline and gunk to tide them over. So I don't believe food is too much of an issue. But it is possible.

Salinity is out of the question. Our salinity remains solid between 1.024 and 1.025 so we're good to go there. We'll be testing everything else today and I'll give you guys an update.

I still think the large CUC we added could be a problem. We have those red leg hermits that are rather larger than we though they'd be. Their bodies are about the size of an emerald crab IMO. just along that size. Not huge, but bigger. And now we have 6 or so emerald crabs in the tank, and they're always bickering with each other. But that doesn't fully explain how the patch of bare "flesh" has appeared on both urchins at the same time. I'll keep you posted

 

Well I guess pics won't be necessary because the urchins are gone. My mom tossed them out when they started looking super terrible while i was out of town. I never got a final look from them, but from what I heard, it wasn't pretty. I'm bummed she didn't keep the skeletons though, those look cool.

Anyways, all params were perfectly fine. Nothing out of whack at all, and the rest of the tank looks fine. I have two suspects. The first is the new CUC we added. All the new crabs and such we added could have been picking at the urchins. My second suspect is coral warfare releasing toxins. our torch coral's sweepers that come out at night have been getting longer and have started brushing up to our duncan coral, causing it to close up partially and look sick. Also, it looks like an entire head on the torch got hit by something where there's only a few coral bits poking out of the skeleton on that head. My mom suspects that toxins in the water from the corals were the problem, and to help get rid of the toxins from the corals fighting she did a 6 gallon WC. but the urchins were already gone at this point. Also, we've had some excess algae blooming on the back glass, which we also suspect is from toxins. We always run carbon, and it was relatively new. But I might want to replace it after this just to be safe. the meany poo torch has been relocated and we'll see what happens from there

 

wow i must be doing something good then bc i have 3 urhans that came with my lr and they are growing like weeds

 

That's great! And I'm very jealous you got three free urchins!!

 

hmmm... you'd think with running carbon that toxins wouldn't get so high. I think its all to do with the hermits. I hate them. Tried to give them a chance twice and both time the little sociopaths ended up banished. First group to the barren eel tank, this time to the fuge and sump.