What determines the color of a coral?

[LeslieS]

Not as in bleached or colorful. As in red, green, or purple.

Is it the coral or the zooxanthellae?

 

[bad coffee]

Zooxanthellae.

Coral skeletons are white. Fleshy tissues are bland colors without zooxanthelle...

B

 

[Deanos]

Zooxanthellae is predominantly brown.

Pigments in the corals tissues determine color.

 

[prattreef]

Actually, I believe most zoox are brown and color is determined by a variety of UV pigments, genetics and other environmental factors. This is a very complex topic. I believe Dana Riddle has been running a series of articles on just this in Advanced Aquarist mag. I think Sanjay might have other references too. Great question Leslie.

 

[bad coffee]

So is it the UV pigments backed by the zooxanthelle? I've never hit a bleached coral with UV light to see. Hmmm

B

 

[ellebelle]

B, I did a quick search of the scientific literature on this topic, and it seems to be incredibly complicated and driven by a variety of factors (though UV comes up most often - it seems that at least some colors provide more protection from UV light than others). Too much UV light can inhibit the Zooxanthellae growth.

 

[noodleman]

its the various proteins that the corals produce, that's why corals without zooxanthelle like suncorals have color also

 

[LeslieS]

lissa, can you give us some bullet points?

noodle, I totally forgot about our non photosynthetic friends.

 

[ellebelle]

Here is part 1 (of seven?) part advanced aquarist article:
http://www.advancedaquarist.com/2006/9/aafeature/view?searchterm=coral coloration

 

[bad coffee]

Thinking about non photos, none of them (that I know of) have colors that 'POP'. they're all normal every day colors. reds, yellows, oranges. bright colors, but not the amazing shades we see with our photosynthetics.

B

 

[prattreef]

This should keep you busy over the holidays

http://www.advancedaquarist.com/2006/9/aafeature/view?searchterm=None
http://www.advancedaquarist.com/2006/11/aafeature2/view?searchterm=None
http://www.advancedaquarist.com/2006/12/aafeature2/view?searchterm=None
http://www.advancedaquarist.com/2007/2/aafeature/view?searchterm=None
http://www.advancedaquarist.com/2007/6/aafeature2/view?searchterm=None
http://www.advancedaquarist.com/2007/7/aafeature1/view?searchterm=None
http://www.advancedaquarist.com/2007/11/aafeature/view?searchterm=None

 

[ellebelle]

lissa, can you give us some bullet points?

noodle, I totally forgot about our non photosynthetic friends.

No, because the reasons vary depending the coral species and the color. I found a couple of interesting articles discussing particularly the green color and the idea that corals with the bright green color occur in shallower waters than brown color morphs of the same species. They did various tests and found that it seemed to protect particularly the zooxanthellae from UV radiation - they even determined specific wavelengths.

I haven't read the advanced aquarist articles fully yet, but they look good - lots of scientific information, but nice and distilled.

 

[LeslieS]

This should keep you busy over the holidays

good thing I have the week off!

 

[noodleman]

Thinking about non photos, none of them (that I know of) have colors that 'POP'. they're all normal every day colors. reds, yellows, oranges. bright colors, but not the amazing shades we see with our photosynthetics.

B

that's because most proteins that can absorb UV light (ie protecting the zooxanthelle from it) are florescent in nature. So that will give you that nice "POP" we all love in our corals :Blurp:

 

[Deanos]

Thinking about non photos, none of them (that I know of) have colors that 'POP'.

Don't confuse fluoresence with color.

 

[fritz]

Good point plus, as mentioned it gets even more complex. Each coral has a type or two of zooxanthelle hosted in their bodies. Each coral will have a different type that likes different conditions. What may cause one to shade its zooxanthelle with UV pigmented proteins may brown another. I posted a thread a year ago or so that listed many sps and the types of zooxanthelle hosted in each (typically). It also listed what conditions were favorable to each type of zooxanthelle. It didn't get many responses and was quickly buried off the main page.

 

[lfsmarineguy]

I think the easiest way to show that it's the corals proteins that create the colors we see as opposed to the brown of the zoox is that each coral can contain more than one type of zoox and if each has it's own color the corals would look more like an abstract painting than the uniform patterns we see (as far as SPS). The color is derived genetically since the schemes are uniform and repeatable.