Corals changing color

[ToddinAtl]

Hi,
I've noticed on a couple corals I've purchased that they were white (or a different color) when I bought them but slowly over time have changed to a tan/flesh color. They seem to be doing fine growth wise, but what is a sign of being more healthy, the original white or the tan? These are an Alveapora and a slipper. Actually the Alveapora has changed from white to tan to lime green and is now going back to tan. I have 350 MH and 220 PC lighting on a 80 G. What gives...or does it matter?
Thanks,
TOdd

 

[ToddinAtl]

Thanks Len,
I assumed this to be the case, but what accounts for the lime green color of the Alveapora? Is it wanting more light?
Thanks,
Todd

 

[Super Len]

Zooxanthellae are various shades of brown. Corals themselves are responsible for the bright green, blue, pink, purple, et. al. coloration. Coral tissue is actually capable of converting one spectrum into another via fluorescening proteins. There are six pigments currently isolated, although exact mechanisms and purposes aren't known. The two dominant theories for the possible uses of these pigments include UV protection (UV radiation converted to "safe" green spectrum) and increasing photosynthetically available radiation in the immediate area (converting red/orange spectrum to usuable blue/violet). The quality of light (ie differences in spectrum) determines the pigments expressed.

When corals with accessory pigments bleach, what's left behind are these bright colors (minus the brown of zooxanthellae). That's what you observed with your Aleveopora sp.

 

[Super Len]

The tan/brown coloration you're probably seeing is that of zooxanthellae's natural pigements. Zooxanthellae are symbiotic algae (dinoflagellates) that reside in the gastrodermis of several species, providing its host with a significant quantity of energy via photosynthesis.

More often then not, white corals are bleached (ie. coral has expelled its zooxanthellae).

To answer your question, a tan coral is generally healthier then a white one - an acceptable generalization for captive reef specimens.

[ January 21, 2002: Message edited by: Leonard ]</p>