Urchin died

[Reef Pilot]

I had a Tuxedo Urchin die and just wondering what may have caused that. I have other urchins and they all seem to be OK. I thought there was something wrong with him the last few days, as he wasn't moving much and just sat in one corner of the tank. His spines would still move around, so I don't think he was dead, but it didn't look right. Then this morning, he was all white, and I removed him with a net. His spines were all down and broken off, too. What surprised me also, is that he was completely hollow inside, like something ate his insides.

I did see a big hermit crab hanging around him the last couple days, so am not sure if he had anything to do with it.

Any ideas what may have caused my urchin to die?

[Flash]

what are you nitrate levels like in your tank? how big was the urchin.... could have just passed of natural causes if everything else is normal!

[Reef Pilot]

Nitrates are about 10 - 20 right now, but have been much higher in the past. I have had this one almost a year now, and my other urchins (and other tank inhabitants) all seem to be fine.

The urchin was about 3 inches in diameter.

[jorjef]

The EVIL hermit did it.....In the study...... with a dagger.....

[jostafew]

I'm sad to say that I recently lost an urchin (and a couple other inverts) after neglecting my params for way too long, just water changes and top offs. As it turned out my SG was down to 1.020/1.021 which was enough to take out the small tuxedo urchin, the two cleaner shrimp, and my two little red starfish. Pretty dissapointed that I let it get that far, but this incident has put me on a new mission with reefing in general so it's not all bad. In the process I discovered that the calibration on my refractometer was a little off too, so that was contributing to the problem as well.

BTW I had a large pincushion urchin that was OK and a Red Fire Shrimpt that seem to have come out unscathed, so it seems that certain species are definetly more tolerant to those water conditions than others.

A couple other things to consider; is there enough algae growth in the tank to support the urchin? My buddy tried tuxedo urchins twice, both times he lost them after a couple months. In his case the calc/mag/alk levels were pretty low, and not much algae growth at the time. Not sure if those params being low was ultimately whey he lost the urchins, but he has not been successfull with them.

One last comment, I doubt it was the crab that did in your urchin, probably just there for dinner after it had died.

[Reef Pilot]

Someone else suggested to me to check my salinity, but it has always been steady at 1.025, so don't think that is it. My other params, KH, Ca, have also been steady.

Don't have a lot of algae, but still have to clean my glass about once a week. I have a gobie that keeps my sand clean, so no algae there. But I do have lots of coralline algae on the back glass and rocks, and all my urchins seem to like chewing on that.

[monocus]

most likely old age.it got hollowed out by bristle worms and your clean up crew

[whatcaneyedo]

I've had a rock boring urchin for over three years but none of my tuxedos have lived more than 2. They can be killed quite easily too, in my experience a small fluctuation in salinity will certainly do it.

[Reef Pilot]

One of my other urchins is also a Tuxedo, but he was always more active, and loved to carry stuff around on his back. But this one never did, and did not move as much. So maybe he just wasn't as healthy to begin with, although he did last about 10 months or so.

When I feed my fish, no food makes to the bottom, so not sure if urchins need to be fed. I thought they just ate algae and coralline algae. Maybe he did starve.