Urchin spike regeneration Question

[G Santana]

Over that last month my pincushion urchin was looking rather sad, I noticed that it dropped a number of spines off the top of its back and I thought it might be because the tanks algae was not enough to keep it going.
I started to supplement it by giving it nori but it still lost spines.
I recently went on a two week vacation and over that time the urchin seems to have grown new spines.

Now I have never kept an urchin before so this is all new to me.

What type of growth cycle do urchins go through and is this common?

Any input is appreciated!!!

Here he is sporting new spines albeit short spines lol

 

[Gtinnel]

I only have one urchin and he has been banished to my sump for probably close to a year now. When he was in the display tank he lost a lot of spines, although he never seemed to have a "bald" spot. I've read that water parameter issues, specifically nitrate issues, can cause them to drop their spines.

 

[G Santana]

I only have one urchin and he has been banished to my sump for probably close to a year now. When he was in the display tank he lost a lot of spines, although he never seemed to have a "bald" spot. I've read that water parameter issues, specifically nitrate issues, can cause them to drop their spines.

My nitrates have been hovering close to zero for several months and just recently I got them up to 2 on the Salifert test scale by scaling back on skimming and fuge light time.
I'm not sure if that's a cause but at any rate he seems to be recovering.

 

[Gtinnel]

My nitrates have been hovering close to zero for several months and just recently I got them up to 2 on the Salifert test scale by scaling back on skimming and fuge light time.
I'm not sure if that's a cause but at any rate he seems to be recovering.

I've always had issues with low nitrates also, but I googled it and apparently it is high nitrates that cause an urchin to lose its spines. So I have no idea why yours or mine either one lost spines.

 

[G Santana]

I've always had issues with low nitrates also, but I googled it and apparently it is high nitrates that cause an urchin to lose its spines. So I have no idea why yours or mine either one lost spines.

Thank you for the reply!!!

 

[ying yang]

My silver belly wrasse occasionally nips at mine till i bang on glass and point at the wrasse while giving him a mucky look lol
Also did have a halloween hermit i caught few times eating my tuxedo urchin spines and tentacles

 

[G Santana]

My silver belly wrasse occasionally nips at mine till i bang on glass and point at the wrasse while giving him a mucky look lol
Also did have a halloween hermit i caught few times eating my tuxedo urchin spines and tentacles

That's wild lol
I fortunately don't have that problem, no one picks on my bulldozer lol

 

[Gqch]

urchins are sensitive to water quality especially nutreints, few die in my tank already due to no3 out of scale.

 

[Gtinnel]

urchins are sensitive to water quality especially nutreints, few die in my tank already due to no3 out of scale.

Is it just high nutrients or are low nutrient levels hard on them as well?