Longspine urchin - shortspine

[PeterEde]

Has my 7month old urchin got a problem?
His spines used to be long and narrow. Now they are short and think.

 

[davidcalgary29]

Possibly -- if it's lost all of its primary spines, as yours seems to have done. The spines you see seem to be its secondary spines. Are you feeding it? What are your parameters?

 

[PeterEde]

Possibly -- if it's lost all of its primary spines, as yours seems to have done. The spines you see seem to be its secondary spines. Are you feeding it? What are your parameters?

There is an abundance of coralline and other algae otherwise I don't feed it.
Parameters are what they have been for 7 months.
the last ICP advised daily dosing iodine at 1.4ml per day. I have now stopped that.

 

[davidcalgary29]

Parameters are what they have been for 7 months.

Yes, but what are they?

Starving urchins may drop their spines, and your urchin may not be getting sufficient nutrition from coralline algae. Mine have access to nori.

 

[PeterEde]

Possibly -- if it's lost all of its primary spines, as yours seems to have done. The spines you see seem to be its secondary spines. Are you feeding it? What are your parameters?

Could it be low calcium?

 

[davidcalgary29]

Unlikely, but you'd have to post numbers first for us to know. Nudge, nudge.

 

[WVNed]

You need to feed it. I give mine

 

[PeterEde]

Yes, but what are they?

Starving urchins may drop their spines, and your urchin may not be getting sufficient nutrition from coralline algae. Mine have access to nori.

I stuck some Nori under it last night. It seems to have eaten most of it.
Temp 25
Salinity 35.8
PH 8.3
ALK 8
NH3 .3
No2 .2
No3 31.2
Po4 .1
Cal 360
Mg 1400

It's not losing spines that I can see. They just seem shorter and fatter.
Current numbers are due to replacing 1/2 the substrate with a coarser grain aragonite instead of sand.

 

[davidcalgary29]

Nothing seems too out of line -- my nitrates are higher than that -- so I'd say that feeding is the key. Urchin spines don't really change shape, so it's most likely that it shed its primary spines over the past month without you noticing, and probably due to starvation. If you don't want to keep feeding it nori, I'd certainly invest in some sinking algae pellets. They really do need more algae than most people feed them; if you're looking for something that can survive on less, tuxedo urchins are a much better choice.

 

[PeterEde]

Nothing seems too out of line -- my nitrates are higher than that -- so I'd say that feeding is the key. Urchin spines don't really change shape, so it's most likely that it shed its primary spines over the past month without you noticing, and probably due to starvation. If you don't want to keep feeding it nori, I'd certainly invest in some sinking algae pellets. They really do need more algae than most people feed them; if you're looking for something that can survive on less, tuxedo urchins are a much better choice.

I have a small tuxedo I found as well. It has found it's way into the over flow. I can see I'll be pulling the plumbing apart sometime to get it out