Black Brittlestar ( Ophiocomina nigra ) coloration?

[mr_bill]

I have what I believe to be a standard black brittlestar but was wondering about the coloration. The pictures I've found on the web show a more brownish star with only the disc being closer to a black color as shown below. The brittle I have is pure black, no brown at all and the spines on the legs are pure black as well, not the light color you see in the picture. The star has retreated into the large clove coral colony it calls home after I fed it some cut shrimp last night so I'll have to wait a day to get any kind of real picture of the specimen in my tank. Any thoughts welcome, and this brittle has grown quite a bit since I first noticed a tiny arm 6 months ago.

 

[ophiura]

No, Ophiocomina nigra is not common in this hobby (not to mention it is a cold water species around the British Isles and the like)
The typical black brittlestar is Ophiocoma wendtii, or Ophiocoma erinaceus.
But many pictures are identified quite wrong.
Ophiocoma wendtii will also appear lighter at night, and sometimes has reddish tube feet.

 

[ophiura]

This shows the day (dark) and night (light) coloration of Ophiocoma wendtii. Its other distiguishing characteristic is long thin arm spines that are kinda cylindrical on the upper part of the arm. Erinaceus has "fatter" shorter arm spines.

 

[mr_bill]

Originally Posted by ophiura
This shows the day (dark) and night (light) coloration of Ophiocoma wendtii. Its other distiguishing characteristic is long thin arm spines that are kinda cylindrical on the upper part of the arm. Erinaceus has "fatter" shorter arm spines.

Thanks Ophiura, I have the Ophiocoma wendtii brittle star also, and this hitchhiker is not even close to the same coloration, but the the arms structure is very similar. This very dark brittle came into my tank via a large clover coral colony I purchased quite a while ago and this star has never come completely out of the coral, it just extends arms from within the corals skeleton.
Wendtii in my old tank, he/she seems to like sand alot better in new tank.

the coral the black colored brittle came on

 

[ophiura]

Ah, well that makes it virtually impossible for us to identify, I am afraid. There could be dozens of possibilities, and color is a poor characteristic to use to identify brittlestars. In fact, as color is lost once they are preserved, it is not often noted at all.

 

[mr_bill]

I'm going with your 2nd opinion. Ophiocoma erinaceus matches very closely to my hitchhiker.
I've wondered if I should cut the old skeleton of the coral away a bit so that I can free this one from the cage it's in right now. I don't think the disc would clear the small openings available.