What are those violet things on my new sea urchin (mespilia globulus) and question about behavior?

[itelshot]

Today i bought my first sea urchin. It was on it's way about 6 hours in a bus. Firstly, i was surprised that it hadn't got purple-blue lines like it was on the internet, now i can see that it starts to release that short purple-blue "hair" in places where lines should be. I'm just curious:
1. What are those purple-blue organs for and what are they called? (As i understand he retracted them cause of stress, correct me if i'm wrong)
2. Why he dont want to go down the glass and he stays near the surface of the water and crawls left and right instead (probably stress also)

 

[Stomatopods17]

I'm going blank on the ID but its not a tuxedo urchin if that's what you're trying to find, it looks like a regular pincushion.

The purple is likely just color, tube feet, or the shorter coat of spines.

Both these species are harmless, pincushions get a little bigger and will still occasionally pick up stuff but not as excessively as tuxedos.

 

[itelshot]

I'm going blank on the ID but its not a tuxedo urchin if that's what you're trying to find, it looks like a regular pincushion.

The purple is likely just color, tube feet, or the shorter coat of spines.

Both these species are harmless, pincushions get a little bigger and will still occasionally pick up stuff but not as excessively as tuxedos.

I can't recognize whether it's globulus or pincussion. It doesn't look like a complete different from either. I was cheated at the store... I hope either way it will do a good job with the algae.

 

[ISpeakForTheSeas]

Hard to say for sure what urchin from the pics, but maybe the Multicolor Globe Urchin, Tripneustes gratilla (A.K.A. the Halloween Urchin or Collector Urchin)?

If so, it's an algae eater and should be reef-safe (though it will carry things around).

1. What are those purple-blue organs for and what are they called? (As i understand he retracted them cause of stress, correct me if i'm wrong)

The organs are called pedicellariae - they're defensive organs with a venomous "bite," but Halloween Urchins can't hurt humans with them. If it retracted them, it's probably recovering from feeling stressed.

2. Why he dont want to go down the glass and he stays near the surface of the water and crawls left and right instead (probably stress also)

How is the flow/aeration in your tank, and how much algae do you have in the tank? Any pics of it and any descriptions of your setup (powerheads, filters, etc.)?

 

[itelshot]

Hard to say for sure what urchin from the pics, but maybe the Multicolor Globe Urchin, Tripneustes gratilla (A.K.A. the Halloween Urchin or Collector Urchin)?

If so, it's an algae eater and should be reef-safe (though it will carry things around).

The organs are called pedicellariae - they're defensive organs with a venomous "bite," but Halloween Urchins can't hurt humans with them. If it retracted them, it's probably recovering from feeling stressed.

How is the flow/aeration in your tank, and how much algae do you have in the tank? Any pics of it and any descriptions of your setup (powerheads, filters, etc.)?

185 liters, 75x45x55h. 2 Jebao MDC pumps on 30% (minimum) gear. Lots of algae on scapes.
Yeah maybe i should gently scrape him with something like a card, cause as u can see, 1 pump infront and one aside are blowing almost directly at him and maybe stresses?
There is bubble magus curve 3 in sump, so i think along with algae in display and no fish there should be plenty of oxygen

 

[itelshot]

185 liters, 75x45x55h. 2 Jebao MDC pumps on 30% (minimum) gear. Lots of algae on scapes.
Yeah maybe i should gently scrape him with something like a card, cause as u can see, 1 pump infront and one aside are blowing almost directly at him and maybe stresses?
There is bubble magus curve 3 in sump, so i think along with algae in display and no fish there should be plenty of oxygen

mlw-20 pumps*

 

[ISpeakForTheSeas]

Yeah, definitely no shortage of flow or algae in that case - I'd probably give it a couple of days to let it settle in and see what it decides to do; a lot of critters will stay in the same spot for a couple of days adjusting before they start roaming the tank.

If it still hasn't moved after that, then I'd post back here and see if anyone has any advice beyond just physically moving it elsewhere in the tank.

 

[itelshot]

Yeah, definitely no shortage of flow or algae in that case - I'd probably give it a couple of days to let it settle in and see what it decides to do; a lot of critters will stay in the same spot for a couple of days adjusting before they start roaming the tank.

If it still hasn't moved after that, then I'd post back here and see if anyone has any advice beyond just physically moving it elsewhere in the tank.

I put him on the scape few hours ago, and he even moved on a short distance. I think he's ok now, hope he will get his coluors with pedicellariaes back soon. Gotta get him nice little hats or shells, as i saw on tiktok)
Also red that not moving for few days and daysleep is normal for them)