Do Corals Need Light?

[Tristan]

Do corals need light?

Not exactly.

It is actually the symbiotic, single called algae, called Zooxanthellae, that resides within the corals' tissue that need light.


The zooxanthellae produce the oxygen, that the corals need to survive, by photosynthesis; in return the algae are protected from grazing species and can access the nutrients that the coral excretes - a mutually beneficial association.

Thoughts Down Below

 

[saltyfilmfolks]

in return the algae are protected from grazing species and can access the nutrients that the coral excretes

not quite but your on the right track. Re-research.

 

[AcroNem]

In my short opinion on this, it comes down to a huge, and definite, yes.
Yes they do.

 

[saltyfilmfolks]

My carnation coral doesn't need light.

 

[AcroNem]

Your carnation coral is azooxanthellate

 

[saltyfilmfolks]

Yes. It is a coral that doesn't need light.

 

[ngvu1]

Sun corals dont

 

[Blue Lip]

Zooxanthellae produce multiple things for their host. They give their host color. They also produce oxygen. Sometimes people will have a coral or anemone start to bleach. The zooxanthellae is producing too much oxygen under the strong lighting conditions of a reef tank. Oxygen can reach toxic levels within the hosts tissue. The host expels the zooxanthellae to prevent the toxic level of oxygen leaving the host faded and a bleached look. To prevent this dose iodine. Iodine helps the host expell the excess oxygen & it can keep more zooxanthellae & color. Zooxanthellae does more than produce oxygen though.

 

[CodyRVA]

No Light Required...

 

[Randy Holmes-Farley Verified Community Expert]

Perhaps this is not the best place for this "advanced" topic, but I wonder if folks could keep photosynthetic corals (hard or soft) under conditions where they can thrive in the dark.

Providing enough food, both dissolved and particulate form might work, and seeing if this works could be quite interesting.

Zooxanthellae, for example are known to take up and use acetate, and I got corals and anemones to brown up with enough acetate via vinegar. Seems to happen with sugar too. It might not take many compounds like that in the water at sufficient concentration to succeed, although one might need to constantly battle bacteria.

Just food for thought...

 

[beaslbob]

I though one of the definitions of coral was it used light?

 

[saltyfilmfolks]

Perhaps this is not the best place for this "advanced" topic, but I wonder if folks could keep photosynthetic corals (hard or soft) under conditions where they can thrive in the dark.

Providing enough food, both dissolved and particulate form might work, and seeing if this works could be quite interesting.

Zooxanthellae, for example are known to take up and use acetate, and I got corals and anemones to brown up with enough acetate via vinegar. Seems to happen with sugar too. It might not take many compounds like that in the water at sufficient concentration to succeed, although one might need to constantly battle bacteria.

Just food for thought...

I like thought food.
Im trying to get brown out of some soft corals, and is (now that Ive had some thought food) one of the reasons why Im not going to use the vinegar and Kalk method like I had been considering.

I though one of the definitions of coral was it used light?

nope. Its an adaptation.

 

[MOPAR]

Not all corals are photosynthetic so some don't need light as mentioned. Weather or not photosynthetic corals could live in no light if ample food was provided is an interesting question. I assume the answer is no as non photosynthetic corals require heavy feeding wouldn't we see photosynthetic corals pop up in the same places rather than higher on the reef in nature?

 

[Randy Holmes-Farley Verified Community Expert]

Not all corals are photosynthetic so some don't need light as mentioned. Weather or not photosynthetic corals could live in no light if ample food was provided is an interesting question. I assume the answer is no as non photosynthetic corals require heavy feeding wouldn't we see photosynthetic corals pop up in the same places rather than higher on the reef in nature?

Only if those needed foods were sufficiently available in nature in deep water. Presumably they are not.

It may take very different foods than deep water corals normally consume to get a normally photosynthetic coral to live in the dark, since they are not adapted in the same way as deep water corals.

 

[saltyfilmfolks]

I assume the answer is no as non photosynthetic corals require heavy feeding wouldn't we see photosynthetic corals pop up in the same places rather than higher on the reef in nature?

This turns to the question of adaptation an the reason why there are both types of coral. If an animal lands in a place where it can survive by either eating solid food/ absorbing nutrients or lacking that develop another means of feedin or carbon exchange by photosynthesis. it will do so but over a LOOONG period of time, and adapt to that environment by evolving the best feeding strategy.
Some zoa in a tank with poor light will live if it has ample sold food/nutriens. But with different colors(brown) a zoa in a tank with great light will live with little solid food/nutrients but great color but perhaps smaller bodymass.
So looking at my tank, Id say there are some zoa that would better survive in a condition of low or no light and over time would look like aptasia.

 

[Randy Holmes-Farley Verified Community Expert]

So looking at my tank, Id say there are some zoa that would better survive in a condition of low or no light and over time would look like aptasia.

Maybe that's what they are, and you got taken.

 

[saltyfilmfolks]

Maybe that's what they are, and you got taken.

..........................

 

[beaslbob]

Dr. Addy of the Smithsonian found some corals down at 200 meters or more. One thing they were attempting to determine is whether or not the corals were utilizing the very limited available light. They were.
But I just checked their web page and it seems the corals and ecosystem up to 6000 meters have corals.
So I guess the next fad in this hobby will be deep water corals using pressure tank and a column of water miles high to get that pressure. Sound like we'll need FAA approval and lights and wind socks for the tower.