- Have you ever bought an awesome coral online
only to get to something that, well
doesn't look quite the same?
Where you lied to?
Maybe ripped off?
Based on an article published back in 2015,
no, the corals probably just adapting
to the different conditions in your aquarium.
That process can take as long as six weeks
for some species of Acropora,
for instance, Acropora Millepora.
So let's find out how that works
and it turns out it's actually pretty interesting.
Hi guys and girls,
I'm ReefMan.
And this week we're gonna be talking about
fluorescent protein mediated color polymorphism
in reef corals.
It's big words, but don't worry.
It's not that bad.
So let's dive in.
So what are fluorescent proteins in the first place?
Well, maybe you've been watching my channel for a while.
You might've heard of green fluorescent proteins
which even though the name might suggest it
come in a whole variety of colors,
green fluorescent proteins
and despite their name
are responsible for almost all the reds, the greens,
the purple, and blue colors
that we find in our Acropora coral.
Corals actually makes so much of those proteins
that they can be as much as 14%
of the total soluble protein content in the corals tissue.
There are also chromo proteins.
Those are chemicals, which aren't fluorescent,
but as their name would suggest
they're brightly color chromo.
If you have a colorful coral in your tank
but just doesn't fluoresce when you're in actinic mode.
Well, it's probably chroma proteins
that are giving that coral almost of its color.
And of course there are a whole bunch of similar proteins
and corals can produce more than one.
A single Acropora Millepora specimen
was actually found to be producing
three different cyan and green fluorescent proteins,
three distinct purple and blue chroma proteins,
and even a red fluorescent protein.
So that's why coral can look so different
under actinic light.
You're seeing the chroma proteins
in everything in normal light
and in actinic light,
you're just seeing the fluorescent proteins
and nothing else.
Okay.
But you know,
how do those proteins actually impact the coral?
Why would they make them?
They don't have eyes.
They can't see their color.
They can't enjoy it.
So why would they make it?
Why would they change
the concentration of these proteins over time?
Well, it's actually the genes that make these proteins.
That's interesting here.
It turns out those genes are light regulated.
And if you increase the brightness of your lights,
your Acropora are going to make even more
of those fluorescent proteins in response.
Up to a limit, of course
I do not endorse cooking your coral under your lights,
just to get a bright, bright colors.
Conveniently, fluorescent proteins work by absorbing light
and then remitting it at a different wavelength.
Actually, that's the definition of fluorescence
and the fluorescent proteins that we find in corals
are particularly good at capturing
and reflecting the wavelengths that make up sunlight
changing it to wavelengths that are better used
by the tiny symbiotic dinoflagellates that are living
in the coral's tissue.
This actually protects the tiny dinoflagellates
from basically getting sunburn.
And that's not to say that those proteins
are not doing anything else in the coral.
They almost certainly are.
We just don't know exactly what it might be yet.
In order to make anything at all,
you need a gene that codes for it
that goes for you and me as well,
just like our coral.
And we don't have genes for, for less than proteins.
And so our skin doesn't glow under a black light.
Some genes can be regulated by environmental factors.
Temperature is a common one
but food, medications that you might take
all of that stuff can change how your body is working.
The genes that the coral have,
which control the production of fluorescent proteins
are regulated by the level of light
that the coral is getting.
And particularly the level of light at the blue end
of the spectrum.
Very low light levels mean that the coral
doesn't need to spend any energy on light protection.
It won't make nearly the level of fluorescent proteins
that are coral growing in a highlight environment would.
It won't have the same protection either.
So remember, if you suddenly move a draft brown coral
from a shady spot of your tank
to a bright spot in your tank,
it might just die.
Remember, it takes upwards of six weeks
for the coral to readjust to a change in light.
So a lengthy acclimation period is particularly important
when you're going from a low light level
to a higher light level.
Now, it's not just light that can turn on and off genes.
For example, in Acropora hyacinthus,
We've found that heat stress can result in the coral
making a whole lot more of a certain protective protein
and antioxidant enzymes,
things that help it survive
in an increased hot water temperature.
So it's not just light that could be browning your corals.
It can be heat as well.
Although, he does usually result
in lighter less saturated colors,
also known as bleaching
because the coral is spending a lot of energy
on heat protection instead of light protection.
All right.
But you know, okay,
if you've ever looked at coral in the wild
or in a fish store,
sometimes you can find a bright colony growing
right next to a drab one.
They're in the same conditions.
They might even be the same species.
So what gives, well,
the answer here is a bit complex
and I would encourage you to read more
and it involves tiny changes in genes called indels.
The sequence that creates these proteins is in fact
influenced by those tiny changes.
And that leads to more or less copies
of the fluorescent proteins being produced
are the genes that code for those proteins, at least.
Now a single sequence of DNA
can code for more than one copy of a given protein
and the overall genome
codes for a whole bunch of the same protein.
So it can make many copies all at once.
Add in those indel variations and a single coral species
can have wildly different numbers of sites
in their genetic material that code
flagellates and proteins.
And so this coral might have a lot
and the next coral might just not have as much.
So that explains the crazy variation
that we can see in species like Acropora loripes, as well
where we can find all manner of colors,
but a single piece, you know,
you can't coax your generic Acropora loripes
into the Walt Disney Acropora loripes
just by giving it more light in some food.
It's really embedded in the genetics of the coral.
If you would like to learn more and I encourage you to
there's really a great paper link down below.
It's a great read,
particularly if you're interested in genetics
and that sort of thing.
Also, hey.
Consider subscribing to the channel if you got this far.
Let me know what you thought of the video down below
in the comments.
Have a great day.
Be kind to each other and stay safe out there.
Bye.