Green Star Polyps ?

[techniner]

OK I have some gsp's and they were going along my rock nicely...

Now it seems that a big portion of it about 30% or so has turned purple.

Now I understand when it is "growing" it will do this.. but this is where it was living previous.

Is this coral dying ?

What can I do ??

Should I do a water change ?

[akula]

tagging along for GSP info.

[tdwyatt]

The purple portion is part of the mat that these organisms produce to attach to the rock and share nutrition/respiration/etc. When conditions change, the polyps may pull back into the mat, and the mat may be completely smooth or somewhat nodular with slightly raised calyces. Although they usually will stay extended, they may (slowly) pull completely back into the encrusting base.

two organisms are often called GSP, Briareum spp. a gorgonians with two distinct genotypes, and Pachyclavularia spp., in particular, P. violacea. Both may have purple mats, but the Briareum spp. have a rind like mat that usually has two layers with different colors for each layer, and will assume an occasional vertical growth form, whereas the Pachyclavularia spp. will have a stoloniferous mat with one color throughout (usually). Briareum spp. will also occasionally produce mucous sheet when disturbed, whereas the Pachyclavularia spp. do not. Pachyclavularia spp. are characterized by 8 non-pinnuled tentacles that are fully retractable into the stolon, usually surrounding an oral opening of a contrasting color.

Many suggestions that the two are actually related spp. with a common ancestor, separated by time into Atlantic and Pacific variations, however, much of the latest work in this area finds many differences in terms of their metabolism and metabolic products (indicators of different evolutionary paths).

Retraction of the polyps may occur in the presence of higher concentrations of iodines and Aluminum compounds (as in some brands of Aluminum Oxide phosphate sponges), and may lead to the ultimate demise of a colony. You may need to blow away accumulations of sediment and/or detrital debris to prevent retraction and potential algal overgrowth of the colony.


Couldn't think of anything else,
HTH

[tims]

there are a few differant types. mine is a nice purple and has always been. it does go thru growth spurs but never really seen and bed color changes..
you could check your water, and your lights.. also if you are not .. run some carbon. make sure noone in the tank is fighting with each other..

what color was the mat before turning purple?

[Clownfishman]

yeah mine has a purple mat to... I bought a frag of it for a small colony... I don't feed it anything though.... I think its zooxanthella algae or whatever is its main source of food from photosyntheses.