Ophiuroidea identification

[caliptratus]

Hi Anthony :

I am researching about a brittle star of Ophiuroidea class.
I have asked in several forums but I do not get an answer.

This is a link with the photos ( Sorry, I am very bad photographer) :

http://www.todomarino.com/forum/attachment.php?attachmentid=2404

and

http://www.todomarino.com/forum/attachment.php?attachmentid=2405

In the begining I think about the unpopular Ophiarachna incrassa or Green Brittle Star.

But I note that the central part of the body is pentagonal and lobular.
The arms project from the convex area of the body.

The entirety of photos taht I saw (Ophiarachna incrassa) the arm project from the vertex of pentagon angles. And the body is a perfect pentagon with straight sides.

I only have an intuition about the class and it is Ophiocoma alexandri.

If you could please help me, I would be very pleased.

In adition, I would like answer you about a hypothetical symbiosis relation between a class of Ophiuroidea and the Sarcophytons coral. It is true?


Best Regards


P.D.: I am researching in the identification and I belive that it is Ophiotrix fragilis. Are you in agreement with it?

Thank you very much