Wire Black Coral helix asymmetry

[Hill]

TL;DR

While diving around the island where I live, I've noticed that this coral always makes a right-handed helix. I saw dozens of them and never one turning left.

I wonder about a mechanism that causes this asymmetry. I have a hypothesis but would like to hear fresh ideas. Thank you.

I'd be happy to provide as many details as I know.

 

[berkeman]

Just curious, why is it called Wire Black Coral when it's white?

 

[Hill]

Just curious, why is it called Wire Black Coral when it's white?

AFAIK, there are no black corals in nature. The corals become black after they are hardened by cooking in some chemicals, and this is done for marketing purposes.

 

[Hill]

AFAIK, there are no black corals in nature. The corals become black after they are hardened by cooking in some chemicals, and this is done for marketing purposes.

Also, many corals are really shades of red, but because of the absorption of red light in water, they look black while at depth, until one flashes a white light on them.

 

[Hill]

Sorry, @berkeman. My post above, #4, meant to add to the answer to your question, but I've accidentally quoted myself instead.

 

[DaveC426913]

A related question here, with some citations you might find informative.

Thread 'What causes the asymmetry in a symmetrically developing organism?'

Dec 20, 2025

As child, before I got my first X-ray, I used to fantasize that I might have a mirror image anatomy - my heart on the right, my appendix on the right. Why not?

(Caveat: I'm not talking about sci-fi molecular-level mirroring. We're not talking starvation because I couldn't process certain proteins, etc.) I'm simpy tlakng about, when a normal zygote divides, it technically has two options which way to form. Oen would expcet a 50:50 split.

But we all have our heart on the left and our appendix on the right (with the exception of congenital deformities).

It's...

• DaveC426913
• Replies: 22
• Forum: Biology and Medical

(Please ignore all the fat-fingered typos. Good lord! I count five in one paragraph!)

 

[Hill]

A related question here, with some citations you might find informative.

Thread 'What causes the asymmetry in a symmetrically developing organism?'

Dec 20, 2025

As child, before I got my first X-ray, I used to fantasize that I might have a mirror image anatomy - my heart on the right, my appendix on the right. Why not?

(Caveat: I'm not talking about sci-fi molecular-level mirroring. We're not talking starvation because I couldn't process certain proteins, etc.) I'm simpy tlakng about, when a normal zygote divides, it technically has two options which way to form. Oen would expcet a 50:50 split.

But we all have our heart on the left and our appendix on the right (with the exception of congenital deformities).

It's...

• DaveC426913
• Replies: 22
• Forum: Biology and Medical

(Please ignore all the fat-fingered typos. Good lord! I count five in one paragraph!)

That discussion does not apply here, not directly anyway, the reason being that the coral in question is not an organism - it's a colony.

 

[berkeman]

I wonder about a mechanism that causes this asymmetry

@BillTre

 

[berkeman]

But we all have our heart on the left and our appendix on the right (with the exception of congenital deformities).

I dated a woman in undergrad who had this syndrome. It affects about 1/10,000 folks, and can lead to misdiagnoses in EMS (she had an appendicitis episode that was initially misdiagnosed and delayed her treatment).

 

[BillTre]

"I wonder about a mechanism that causes this asymmetry"

@BillTre

Trivially, since I don't know anything about it, I would guess unequal growth.

 

[berkeman]

I have a hypothesis but would like to hear fresh ideas.

Okay, since we don't seem to have any good responses, what has your reading shown you so far?

 

[Hill]

Okay, since we don't seem to have any good responses, what has your reading shown you so far?

Unfortunately, nothing.
It seems to be a completely unknown phenomenon.
I asked this question a biologist who has published papers on black corals, albeit not specifically this one. He replied that he didn't notice such a phenomenon and that, in his experience, they occur in both senses. As evidence, he attached four photos taken by him. Now, the punch line, in all four photos the corals were right-handed.

 

[Hill]

I doubt this thread will continue. So, for the finale, here are two more photos of the beauties.

 

[DaveC426913]

I have never seen anything like that.
Fascinating.

Are all the right-handed ones on the same side of the equator? Just asking.

 

[Hill]

I have never seen anything like that.
Fascinating.

Are all the right-handed ones on the same side of the equator? Just asking.

Yes, but I'm taking these photos fairly close to the equator.

 

[DaveC426913]

And where were the left-handed ones seen?

 

[Hill]

And where were the left-handed ones seen?

There are no left-handed ones that I'm aware of.

 

[Hill]

Just curious, why is it called Wire Black Coral when it's white?

https://en.wikipedia.org/wiki/Black_coral has a different answer to this question:

Despite its name, a black coral is rarely black, and depending on the species can be white, red, green, yellow, or brown. The corals derive their name from their black skeletons, which are composed of protein and chitin.

However, the "skeletons" are not always black either.
E.g.,
https://en.wikipedia.org/wiki/Cirrhipathes#/media/File:Cirripathes_sp_(Spiral_Wire_Coral).jpg

 

[256bits]

which are composed of protein and chitin
Your answer is in there somewhere. The laying down of the components has to have some electrical or chemical offset that produces the coiling. Probably not from the helicity at the nano scale of assembly.

Cellulose does the same twisting for plants - is vines.

Here is some discussion of chitin on the nano to macro scale, regarding colour, iridescence of insects and the like, and colours from cellulose in plants. As well as twisting - macro needs more research to explain it all.
https://hal.science/hal-04202351v1/file/Adv Funct Mat 2023_M Mitov.pdf

 

[Hill]

which are composed of protein and chitin
Your answer is in there somewhere. The laying down of the components has to have some electrical or chemical offset that produces the coiling. Probably not from the helicity at the nano scale of assembly.

Cellulose does the same twisting for plants - is vines.

Here is some discussion of chitin on the nano to macro scale, regarding colour, iridescence of insects and the like, and colours from cellulose in plants. As well as twisting - macro needs more research to explain it all.
https://hal.science/hal-04202351v1/file/Adv Funct Mat 2023_M Mitov.pdf

Thanks a lot.
This certainly is a

fresh idea

I am looking for.

 

[256bits]

I am looking for.

All I did was added to the response of @BillTre regarding unequal growth.
The finer details of the mechanism has still not been explained, such as why the dedicated spiral, and not haphazard.

 

[Hill]

... added ...

Your addition was new.