Hi guys, welcome back to Tidal Gardens.
When it comes to reproductive methods, corals have a diverse skill set.
They are capable of sexual reproduction as well as a variety of asexual methods such
as longitudinal fission seen in corals like Caulastrea, budding as seen in corals like
frogspawn, or pedal laceration seen in mushrooms, and especially fragmentation which makes companies
like Tidal Gardens possible.
There is however a much less common method which is the subject of this video.
Polyp.
Bailout.
Ok, roll that intro!
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Polyp bailout is a stress response to unfavorable tank conditions that certain stony corals
can activate as a last ditch effort to save themselves.
You may have seen corals express stress reactions in other forms.
For example, regulating zooxanthellae can be seen whether it is “browning out” to
increase the population or “bleaching” which is essentially expelling zooxanthellae.
Some corals prefer low light and as a stress response to too much light might form oxide
radicals in their bodies that resemble bounce mushroom bubbles.
It is part of the reason why the first time I saw a bounce mushroom the first thing I
thought was it was just a regular Rhodactis with horrible tumors.
Anyway, those are just some examples of stress reactions that are fairly common.
Polyp Bailout is a much more extreme measure which I liken it to a fighter pilot hitting
the eject seat and hoping for the best.
During Polyp Bailout, Polyps are killing off their own connective tissue through apoptosis.
For those that are unfamiliar with the term, apoptosis is programmed cell death as opposed
to necrosis which is traumatic cell death.
Apoptosis is a highly regulated and controlled process so the coral polyps bailing out due
to stress are doing so in a direct calculated response to an exogenous threat.
It is certainly not a common occurrence but over the years I’ve seen it happen in SPS
like Pocillopora, and Stylophora as well as LPS such as Euphyllia and Catalaphyllia.
The SPS corals seem to do this much more successfully, but perhaps it is just a numbers game.
A colony of Pocillopora or Stylophora might expel a hundred polyps during a polyp bailout
event where only a small fraction survive and regrow on a more favorable substrate.
This is in contrast to a large polyp stony coral like an elegance where it is just a
single polyp with a sliver of a chance of survival after bailing out.
When things go right however, it is an unexpected surprise.
We tend to see SPS colonies pop up seemingly out of nowhere on the side glass of the aquarium
or an overflow box.
Although much less common, here is a head of Frogspawn that detached in horrific fashion
to regrow on the bottom of the tank.
This little head has survived now over 6 weeks so I think it is well on its way to recovery.
So what causes a coral to decide to bail out?
That is not so clear, but there are a number of possibilities.
First off is any shift in temperature.
In a home aquarium temperatures are relatively stable as compared to my greenhouse for example,
BUT when something goes wrong in a home aquarium temperature-wise the effect is way more severe.
Small water volumes can either heat up or cool down very quickly and that could cause
this type of stress response in coral.
Similarly, sharp changes in salinity could be the cause.
Again, it is not typical for an aquarium to go crazy salinity-wise, but it could happen
especially when the testing device has not been calibrated in a while and the readings
might have drifted significantly.
I’ve seen a refractometer be off by a whole .005 so a reading of 1.025 was ACTUALLY 1.030.
On top of that, there were plenty of times where that tank was giving readings of 1.028
or 29 meaning the specific gravity of that tank may have drifted towards 1.035 which
is WAY too high.
Having said that, the animals in the aquarium may have a muted stress response to that salinity
because that sort of change happens gradually BUT the moment you get that new coral, that
poor little sucker is going to be in a world of stress.
Even if you took an insanely long time to acclimate it, there is a really big difference
between acclimating a coral for an hour and slowly changing salinity over a few months.
So THAT could be a stress inducing event that could activate polyp bailout.
Three… there could be a chemical change in the aquarium which could be either too
little nutrient or too much nutrient.
I’ve seen one scientific journal describe polyp bailout happening to a specimen with
low food availability and I’ve personally seen it happen in systems with an overabundance
of nutrient and high nitrate.
Lastly, I could see corals bail out due to some manner of pest infestation or harassment
from a fellow tank inhabitant like a fish or invert.
Ok, that does it for this short overview of polyp bailout.
I hope you never have to experience it happen in your aquarium, but it is something to be
aware of none the less.
This hobby isn’t always puppy dogs and rainbows and occasionally our tank lets us know when
we are being unfit coral parents.
Anyway, I hope you enjoyed the video.
As always, don’t forget to like, comment, and subscribe and until next time, happy reefing.